Publications by authors named "Ajayan Vinu"

121 Publications

Distribution, behaviour, bioavailability and remediation of poly- and per-fluoroalkyl substances (PFAS) in solid biowastes and biowaste-treated soil.

Environ Int 2021 May 5;155:106600. Epub 2021 May 5.

Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA; Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.

Aqueous film-forming foam, used in firefighting, and biowastes, including biosolids, animal and poultry manures, and composts, provide a major source of poly- and perfluoroalkyl substances (PFAS) input to soil. Large amounts of biowastes are added to soil as a source of nutrients and carbon. They also are added as soil amendments to improve soil health and crop productivity. Plant uptake of PFAS through soil application of biowastes is a pathway for animal and human exposure to PFAS. The complexity of PFAS mixtures, and their chemical and thermal stability, make remediation of PFAS in both solid and aqueous matrices challenging. Remediation of PFAS in biowastes, as well as soils treated with these biowastes, can be achieved through preventing and decreasing the concentration of PFAS in biowaste sources (i.e., prevention through source control), mobilization of PFAS in contaminated soil and subsequent removal through leaching (i.e., soil washing) and plant uptake (i.e., phytoremediation), sorption of PFAS, thereby decreasing their mobility and bioavailability (i.e., immobilization), and complete removal through thermal and chemical oxidation (i.e., destruction). In this review, the distribution, bioavailability, and remediation of PFAS in soil receiving solid biowastes, which include biosolids, composts, and manure, are presented.
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http://dx.doi.org/10.1016/j.envint.2021.106600DOI Listing
May 2021

Mitigation of petroleum-hydrocarbon-contaminated hazardous soils using organic amendments: A review.

J Hazard Mater 2021 Mar 22;416:125702. Epub 2021 Mar 22.

Global Centre for Environmental Remediation, The University of Newcastle, Callaghan, NSW 2308, Australia. Electronic address:

The term "Total petroleum hydrocarbons" (TPH) is used to describe a complex mixture of petroleum-based hydrocarbons primarily derived from crude oil. Those compounds are considered as persistent organic pollutants in the terrestrial environment. A wide array of organic amendments is increasingly used for the remediation of TPH-contaminated soils. Organic amendments not only supply a source of carbon and nutrients but also add exogenous beneficial microorganisms to enhance the TPH degradation rate, thereby improving the soil health. Two fundamental approaches can be contemplated within the context of remediation of TPH-contaminated soils using organic amendments: (i) enhanced TPH sorption to the exogenous organic matter (immobilization) as it reduces the bioavailability of the contaminants, and (ii) increasing the solubility of the contaminants by supplying desorbing agents (mobilization) for enhancing the subsequent biodegradation. Net immobilization and mobilization of TPH have both been observed following the application of organic amendments to contaminated soils. This review examines the mechanisms for the enhanced remediation of TPH-contaminated soils by organic amendments and discusses the influencing factors in relation to sequestration, bioavailability, and subsequent biodegradation of TPH in soils. The uncertainty of mechanisms for various organic amendments in TPH remediation processes remains a critical area of future research.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125702DOI Listing
March 2021

Ultrafine Copper Oxide Particles Dispersed on Nitrogen-Doped Hollow Carbon Nanospheres for Oxidative Esterification of Biomass-Derived 5-Hydroxymethylfurfural.

Chempluschem 2021 02;86(2):259-269

Department of Chemical Engineering, Institute of ChemicalTechnology, Matunga (E), Mumbai, Maharashtra, 400019, India.

One-pot synthesis of furan-2,5-dimethylcarboxylate (FDMC) from 5-hydroxymethylfurfural (HMF) is highly demanding for the commercial production of polyethylene furanoate (PEF). Herein, a direct synthesis of FDMC is reported from oxidative esterification of HMF using ultrafine CuO particles dispersed on nitrogen-doped hollow carbon nanospheres (CuO/N-C-HNSs) as a catalyst and tert-butyl hydroperoxide (TBHP) as an oxidizing and methylating reagent. The CuO/N-C-HNSs was prepared through a template protection-sacrifice strategy using SiO as a sacrificial template and histidine as the precursor for N and C. N-doping facilitated a strong interaction between the support and copper species, affording formation of CuO nanoparticles of less than 10 nm in size. By virtue of the highly dispersed CuO nanoparticles and a high BET surface area 373 m /g, the CuO/N-C-HNSsshows excellent catalytic performance in the selective conversion of HMF into FDMC affording 93 % yield of the desired product with a TON value of 49. Furthermore, the oxidative esterification involving SP C-H bond functionalization is also demonstrated using the same catalyst.
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http://dx.doi.org/10.1002/cplu.202000713DOI Listing
February 2021

Recent Progress in Polymorphs of Carbon Nitride: Synthesis, Properties, and Their Applications.

Macromol Rapid Commun 2021 Apr 15;42(7):e2000676. Epub 2021 Jan 15.

Global Innovative Centre for Advanced Nanomaterials, School of Engineering, Faculty of Engineering and Build Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia.

Carbon nitride (CN) materials are at the forefront of contemporary solar energy conversion applications, owing to their extraordinary physicochemical properties. Having such multifunctional properties, CN photocatalytic materials are practically significant; however, due to the indistinguishable physical properties, all solid CN materials in most literature reports are referred to as graphitic C N phase, which is incorrect. This perspective discourses the various identified polymeric forms of CN, their molecular structure, synthesis, photophysical properties, and their applications. The article attempts to simplify the conjectures in CN terminology and discuss future perspectives, challenges, and opportunities in the developing field of CN chemistry.
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http://dx.doi.org/10.1002/marc.202000676DOI Listing
April 2021

Colossal Magnetization and Giant Coercivity in Ion-Implanted (Nb and Co) MoS Crystals.

ACS Appl Mater Interfaces 2020 Dec 16;12(52):58140-58148. Epub 2020 Dec 16.

Global Innovative Centre for Advanced Nanomaterials, School of Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia.

Colossal saturation magnetization and giant coercivity are realized in MoS single crystals doped with Nb and/or Co using an ion implantation method. Magnetic measurements have demonstrated that codoping with 2 at % Nb and 4 at % Co invoked a "giant" coercivity, as high as 9 kOe at 100 K. Doping solely with 5 at % Nb induces a "colossal" magnetization of 1800 emu/cm at 5 K, which is higher than that of metallic Co. The high magnetization is due to the formation of Nb-rich defect complexes, as confirmed by first-principles calculations. It is proposed that the high coercivity is due to the combined effects of strong directional exchange coupling induced by the Nb and Co doping and pinning effects from defects within the layered structure. This high magnetization mechanism is also applicable to 2D materials with bilayers or few layers of thickness, as indicated by first-principles calculations. Hence, this work opens a potential pathway for the development of 2D high-performance magnetic materials.
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http://dx.doi.org/10.1021/acsami.0c18150DOI Listing
December 2020

Silica-based Nanoparticles as Drug Delivery Vehicles for Prostate Cancer Treatment.

Chem Rec 2020 Dec 15. Epub 2020 Dec 15.

Global Innovative Centre for Advanced Nanomaterials, Faculty of Engineering and Built Environment.

Prostate cancer (PCa) is one of the most commonly diagnosed cancers and is the fifth common cause of cancer-related mortality in men. Current methods for PCa treatment are insufficient owing to the challenges related to the non-specificity, instability and side effects caused by the drugs and therapy agents. These drawbacks can be mitigated by the design of a suitable drug delivery system that can ensure targeted delivery and minimise side effects. Silica based nanoparticles (SBNPs) have emerged as one of the most versatile materials for drug delivery due to their tunable porosities, high surface area and tremendous capacity to load various sizes and chemistry of drugs. This review gives a brief overview of the diagnosis and current treatment strategies for PCa outlining their existing challenges. It critically analyzes the design, development and application of pure, modified and hybrid SBNPs based drug delivery systems in the treatment of PCa, their advantages and limitations.
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http://dx.doi.org/10.1002/tcr.202000104DOI Listing
December 2020

A review on the valorisation of food waste as a nutrient source and soil amendment.

Environ Pollut 2021 Mar 3;272:115985. Epub 2020 Nov 3.

Global Centre for Environmental Remediation, Faculty of Science, The University of Newcastle, Callaghan, NSW, 2308, Australia; Cooperative Research Centre for High Performance Soil, Newcastle, Callaghan, NSW, 2308, Australia. Electronic address:

Valorisation of food waste offers an economical and environmental opportunity, which can reduce the problems of its conventional disposal. Food waste is commonly disposed of in landfills or incinerated, causing many environmental, social, and economic issues. Large amounts of food waste are produced in the food supply chain of agriculture: production, post-harvest, distribution (transport), processing, and consumption. Food waste can be valorised into a range of products, including biofertilisers, bioplastics, biofuels, chemicals, and nutraceuticals. Conversion of food waste into these products can reduce the demand of fossil-derived products, which have historically contributed to large amounts of pollution. The variety of food chain suppliers offers a wide range of feedstocks that can be physically, chemically, or biologically altered to form an array of biofertilisers and soil amendments. Composting and anaerobic digestion are the main large-scale conversion methods used today to valorise food waste products to biofertilisers and soil amendments. However, emerging conversion methods such as dehydration, biochar production, and chemical hydrolysis have promising characteristics, which can be utilised in agriculture as well as for soil remediation. Valorising food waste into biofertilisers and soil amendments has great potential to combat land degradation in agricultural areas. Biofertilisers are rich in nutrients that can reduce the dependability of using conventional mineral fertilisers. Food waste products, unlike mineral fertilisers, can also be used as soil amendments to improve productivity. These characteristics of food wastes assist in the remediation of contaminated soils. This paper reviews the volume of food waste within the food chain and types of food waste feedstocks that can be valorised into various products, including the conversion methods. Unintended consequences of the utilisation of food waste as biofertilisers and soil-amendment products resulting from their relatively low concentrations of trace element nutrients and presence of potentially toxic elements are also evaluated.
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http://dx.doi.org/10.1016/j.envpol.2020.115985DOI Listing
March 2021

Characterization and Drug Release Control Ability of Chitosan/Lovastatin Particles Coated by Alginate.

J Nanosci Nanotechnol 2020 12;20(12):7347-7355

Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Ha Noi, 100000, Vietnam.

We report on the coating of chitosan/lovastatin particles with a liquid solution of alginate using a 3D printing technique. The prepared particles are characterized by Scanning Electronic Microscopy, Infrared Spectroscopy, Dynamic Light Scattering, Differential Scanning Calorimetry, and Ultraviolet-Visible Spectroscopy. Characterization results reveal that the coating of alginate makes a considerable difference in the structure, morphology, size distribution and zeta potential of the chitosan/lovastatin particles, and the size of the coated particles is increased after the coating. We also demonstrate the drug release ability of the chitosan/lovastatin particles in simulated gastric fluid and controlled in simulated intestinal fluid. Drug release study reveals that the drug release profile of the coated particles varies significantly with the pH of the solution and the coating process significantly reduces the rate of release of the drug. We also report that the bioavailability of lovastatin particles can be improved by coating with the biopolymer layers.
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http://dx.doi.org/10.1166/jnn.2020.18889DOI Listing
December 2020

Borophene: New Sensation in Flatland.

Adv Mater 2020 Aug 14;32(34):e2000531. Epub 2020 Jul 14.

Global Innovative Centre for Advanced Nanomaterials, School of Engineering, Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia.

Borophene, a 2D allotrope of boron and the lightest elemental Dirac material, is the latest very promising 2D material owing to its unique structural and electronic characteristics of the X and β phases. The high atomic density on ridgelines of the β phase of borophene provides a substantial orbital overlap, which leads to an excellent electron density in the conduction level and thus to a highly metallic behavior. These unique structural characteristics and electronic properties of borophene attract significant scientific interest. Herein, approaches for crystal growth/synthesis of these unique nanostructures and their potential technological applications are discussed. Various substrate-supported ultrahigh-vacuum growth techniques for borophene, such as molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition, along with their challenges, are also summarized. The sonochemical exfoliation and modified Hummer's technique for the synthesis of free-standing borophene are also discussed. Solution-phase exfoliation seems to address the scalability issues and expands the applications of these unique materials to various fields, including renewable energy devices and ultrafast sensors. Furthermore, the electronic, optical, thermal, and elastic properties of borophene are thoroughly discussed and are compared with those of graphene and its "cousins." Numerous frontline applications are envisaged and an outlook is presented.
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http://dx.doi.org/10.1002/adma.202000531DOI Listing
August 2020

Recent Advances in the Preparation and Applications of Organo-functionalized Porous Materials.

Chem Asian J 2020 Sep 22;15(17):2588-2621. Epub 2020 Jul 22.

Global Innovative Center for Advanced Nanomaterials Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, 2308, NSW, Australia.

Organo-functionalized materials with porous structure offer unique adsorption, catalytic and sensing properties. These unique properties make them available for various applications, including catalysis, CO capture and utilization, and drug delivery. The properties and the performance of these unique materials can be altered with suitable modifications on their surface. In this review, we summarize the recent advances in the preparation and applications of organo-functionalized porous materials with different structures. Initially, a brief historical overview of functionalized porous materials is presented, and the subsequent sections discuss the recent developments and applications of various functional porous materials. In particular, the focus is given on the various methods used for the preparation of organo-functionalized materials and their important roles in the heterogenization of homogeneous catalysts. A special emphasis is also given on the applications of these functionalized porous materials for catalysis, CO capture and drug delivery.
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http://dx.doi.org/10.1002/asia.202000651DOI Listing
September 2020

Emerging trends in porous materials for CO capture and conversion.

Chem Soc Rev 2020 Jul;49(13):4360-4404

Global Innovative Centre for Advanced Nanomaterials, Faculty of Engineering & Built Environment, University of Newcastle, Callaghan, 2308, Australia.

The presence of an excessive concentration of CO2 in the atmosphere needs to be curbed with suitable measures including the reduction of CO2 emissions at stationary point sources such as power plants through carbon capture technologies and subsequent conversion of the captured CO2 into non-polluting clean fuels/chemicals using photo and/or electrocatalytic pathways. Porous materials have attracted much attention for carbon capture and in the recent past; they have witnessed significant advancements in their design and implementation for CO2 capture and conversion. In this context, the emerging trends in major porous adsorbents such as MOFs, zeolites, POPs, porous carbons, and mesoporous materials for CO2 capture and conversion are discussed. Their surface texture and chemistry, and the influence of various other features on their efficiency, selectivity, and recyclability for CO2 capture and conversion are explained and compared thoroughly. The scientific and technical advances on the material structure versus CO2 capture and conversion provide deep insights into designing effective porous materials. The review concludes with a summary, which compiles the key challenges in the field, current trends and critical challenges in the development of porous materials, and future research directions combined with possible solutions for realising the deployment of porous materials in CO2 capture and conversion.
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http://dx.doi.org/10.1039/d0cs00075bDOI Listing
July 2020

The Influence of Nanoparticle Shape on Protein Corona Formation.

Small 2020 06 14;16(25):e2000285. Epub 2020 May 14.

Future Industries Institute, School of Engineering, University of South Australia, Mawson Lakes, Adelaide, SA, 5095, Australia.

Nanoparticles have become an important utility in many areas of medical treatment such as targeted drug and treatment delivery as well as imaging and diagnostics. These advances require a complete understanding of nanoparticles' fate once placed in the body. Upon exposure to blood, proteins adsorb onto the nanoparticles surface and form a protein corona, which determines the particles' biological fate. This study reports on the protein corona formation from blood serum and plasma on spherical and rod-shaped nanoparticles. These two types of mesoporous silica nanoparticles have identical chemistry, porosity, surface potential, and size in the y-dimension, one being a sphere and the other a rod shape. The results show a significantly larger amount of protein attaching from both plasma and serum on the rod-like particles compared to the spheres. Interrogation of the protein corona by liquid chromatography-mass spectrometry reveals shape-dependent differences in the adsorption of immunoglobulins and albumin proteins from both plasma and serum. This study points to the need for taking nanoparticle shape into consideration because it can have a significant impact on the fate and therapeutic potential of nanoparticles when placed in the body.
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http://dx.doi.org/10.1002/smll.202000285DOI Listing
June 2020

Design of P-Doped Mesoporous Carbon Nitrides as High-Performance Anode Materials for Li-Ion Battery.

ACS Appl Mater Interfaces 2020 May 13;12(21):24007-24018. Epub 2020 May 13.

Energy Storage and Conversion and Catalysis Laboratory, SRM Research Institute and Department of Chemistry, SRM Institute of Science and Technology, Chennai 603203, Tamil Nadu, India.

Herein, we demonstrate a simple and unique strategy for the preparation of P-doped into the substructure of mesoporous carbon nitride materials (P-MCN-1) with ordered porous structures as a high-energy and high-power Li-ion battery (LIB) anode. The P-MCN-1 as an anode in LIB delivers a high reversible discharge capacity of 963 mAh g even after 1000 cycles at a current density of 1 A g, which is much higher than that of other counterparts comprising -triazine (CHN, g-CN), pristine MCN-1, and B-containing MCN-1 (B-MCN-1) subunits or carbon allotropes like CNT and graphene (rGO) materials. The P-MCN-1 electrode also exhibits exceptional rate capability even at high current densities of 5, 10, and 20 A g delivering 685, 539, and 274 mAh g, respectively, after 2500 cycles. The high electrical conductivity and Li-ion diffusivity (), estimated from electrochemical impedance spectra (EIS), very well support the extraordinary electrochemical performance of the P-MCN-1. Higher formation energy, lower bandgap value, and high Li-ion adsorption ability predicted by first principle calculations of P-MCN-1 are in good agreement with experimentally observed high lithium storage, stable cycle life, high power capability, and minimal irreversible capacity (IRC) loss. To the best of our knowledge, it is an entirely new material with the combination of ordered mesostructures with P codoping in carbon nitride substructure which offers superior performance for LIB, and hence we believe that this work will create new momentum for the design and development of clean energy storage devices.
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http://dx.doi.org/10.1021/acsami.0c05123DOI Listing
May 2020

Single-Step Synthesis of Mesoporous Carbon Nitride/Molybdenum Sulfide Nanohybrids for High-Performance Sodium-Ion Batteries.

Chem Asian J 2020 Jun 13;15(12):1863-1868. Epub 2020 May 13.

Global Innovative Center for Advanced Nanomaterials (GICAN) School of Engineering Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW 2308, Australia.

Molybdenum disulfide (MoS ) is a promising candidate as a high-performing anode material for sodium-ion batteries (SIBs) due to its large interlayer spacing. However, it suffers from continued capacity fading. This problem could be overcome by hybridizing MoS with nanostructured carbon-based materials, but it is quite challenging. Herein, we demonstrate a single-step strategy for the preparation of MoS coupled with ordered mesoporous carbon nitride using a nanotemplating approach which involves the pyrolysis of phosphomolybdic acid hydrate (PMA), dithiooxamide (DTO) and 5-amino-1H-tetrazole (5-ATTZ) together in the porous channels of 3D mesoporous silica template. The sulfidation to MoS , polymerization to carbon nitride (CN) and their hybridization occur simultaneously within a mesoporous silica template during a calcination process. The CN/MoS hybrid prepared by this unique approach is highly pure and exhibits good crystallinity as well as delivers excellent performance for SIBs with specific capacities of 605 and 431 mAhg at current densities of 100 and 1000 mAg , respectively, for SIBs.
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http://dx.doi.org/10.1002/asia.202000349DOI Listing
June 2020

Shape and Orientation Controlled Hydrothermal Synthesis of Silicide and Metal Dichalcogenide on a Silicon Substrate.

ACS Appl Mater Interfaces 2020 Apr 10;12(16):18850-18858. Epub 2020 Apr 10.

Global Innovative Centre for Advanced Nanomaterials, School of Engineering, The University of Newcastle, Callaghan, New South Wales 2308, Australia.

Shape-controlled MoS has been grown directly on a silicon substrate, for the first time, with the use of a facile hydrothermal synthesis approach. The growth morphology is dependent on the substrate orientation. Square, hexagonal, and triangular patterns of MoS are grown on Si(100), Si(110), and Si(111), respectively. Detailed studies reveal that Mo silicide is formed at the initial stage, and the formation of silicide patterns is dictated by the different surface energies of Si(100), Si(110) and Si(111). Subsequently, shaped MoS patterns are formed following the silicide ones at the thermodynamic equilibrium. The approach for the formation of these patterns can be generalized to other 2D materials and can also be formed on a large scale by a lithography method. The work has shown a new technique to form silicide via solution processing and grow patterned 2D materials directly on silicon substrates, which may have the potential for advancing next-generation electronic devices.
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http://dx.doi.org/10.1021/acsami.0c01222DOI Listing
April 2020

Emerging Advanced Nanomaterials and their Applications.

Small 2020 03;16(12):e2001287

Global Innovative Center for Advanced Nanomaterials (GICAN), School of Engineering Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia.

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http://dx.doi.org/10.1002/smll.202001287DOI Listing
March 2020

Carbon Nanoflakes and Nanotubes from Halloysite Nanoclays and their Superior Performance in CO Capture and Energy Storage.

ACS Appl Mater Interfaces 2020 Mar 27;12(10):11922-11933. Epub 2020 Feb 27.

Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, New South Wales 2308, Australia.

Nanoporous carbon (HNC) with a flake and nanotubular morphology and a high specific surface area is prepared by using natural halloysite nanotubes (HNTs), a low-cost and naturally available clay material with a mixture of flaky and tubular morphology. A controlled pore-filling technique is used to selectively control the porosity, morphology, and the specific surface area of the HNC. Activated nanoporous carbon (AHNC) with a high specific surface area is also prepared by using HNT together with the activation process with zinc chloride (ZnCl). HNC exhibits flakes and tubular morphologies, which offer a high specific surface area (837 m/g). The specific surface area of AHNC is 1646 m/g, 74 times greater than the specific surface area of pure HNT (22.5 m/g). These data revealed that the single-step activation combined with the nanotemplating results in creating a huge impact on the specific surface area of the HNC. Both HNC and AHNC are employed as adsorbents for CO adsorption at different pressures and adsorption temperatures. The CO adsorption capacity of AHNC is 25.7 mmol/g at 0 °C, which is found to be significantly higher than that of activated carbon (AC), mesoporous carbon (CMK-3), mesoporous carbon nitride (MCN-1), and multiwalled carbon nanotube (MWCNT). AHNC is also tested as an electroactive material and demonstrates good supercapacitance, cyclic stability, and high capacitance retention. Specific capacitance of AHNC in the aqueous electrolyte is 197 F/g at 0.3 A/g, which is higher than that of AC, MWCNT, and CMK-3. The technique adopted for the preparation of both HNC and AHNC is quite unique and simple, has the potential to replace the existing highly expensive and sophisticated mesoporous silica-based nanotemplating strategy, and could also be applied for the fabrication of series of advanced nanostructures with unique functionalities.
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http://dx.doi.org/10.1021/acsami.9b21510DOI Listing
March 2020

Tuning the ATP-triggered pro-oxidant activity of iron oxide-based nanozyme towards an efficient antibacterial strategy.

J Colloid Interface Sci 2020 May 27;567:154-164. Epub 2020 Jan 27.

Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Central Campus, Navrangpura, Ahmedabad 380009, Gujarat, India; Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment (FEBE), The University of Newcastle, Callaghan, New South Wales 2308, Australia. Electronic address:

An alarming increase in bacterial resistance towards various types of antibiotics makes it imperative to design alternate or combinational therapies to treat stubborn bacterial infections. In this perspective, emerging tools like nanozymes, nanomaterials with biological enzyme like characteristics, are being utilised to control infections caused by bacterial pathogens. Among several nanozymes used for antibacterial applications, FeO nanoparticles (NP) received great attention due to their effective peroxidase like activity. The pH dependent peroxidase activity of FeO NP results in generation of OH radical via the unique Fenton chemistry of iron. However, their pH dependent activity is restricted to acidic environment and dramatic loss in antibacterial activity is observed at near neutral pH. Here we describe a novel strategy to overcome the pH lacunae of citrate coated FeO NP by utilizing adenosine triphosphate disodium salt (ATP) as a synergistic agent to accelerate the OH radical production and restore its antibacterial activity over a wide range of pH. This synergistic combination (30 µg/mL FeO NP and 2.5 mM ATP) shows a high bactericidal activity against both gram positive (B. subtilis) and gram negative (E. coli) bacterial strains, in presence of HO, at neutral pH. The synergistic effect (FeO NP + ATP) is determined from the viability assessment and membrane damage studies and is further confirmed by comparing the concentration of generated OH radicals. Over all, this study illustrates ATP assisted and OH-mediated bactericidal activity of FeO nanozyme at near neutral pH.
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http://dx.doi.org/10.1016/j.jcis.2020.01.099DOI Listing
May 2020

Thermodynamically Stable Mesoporous C N and C N with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction.

Small 2020 03 29;16(12):e1903572. Epub 2019 Nov 29.

Global Innovative Center for Advanced Nanomaterials (GICAN), School of Engineering, Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia.

Carbon nitrides with a high N/C atomic ratio (>2) are expected to offer superior basicity and unique electronic properties. However, the synthesis of these nanostructures is highly challenging since many parts of the CN frameworks in the carbon nitride should be replaced with thermodynamically less stable NN frameworks as the nitrogen content increases. Thermodynamically stable C N and C N with an ordered mesoporous structure are synthesized at 250 and 300 °C respectively via a pyrolysis process of 5-amino-1H-tetrazole (5-ATTZ). Polymerization of the precursor to the ordered mesoporous C N and C N is clearly proved by X-ray and electron diffraction analyses. A combined analysis including diverse spectroscopy and FDMNES and density functional theory (DFT) calculations demonstrates that the NN bonds are stabilized in the form of tetrazine and/or triazole moieties in the C N and C N . The ordered mesoporous C N represents the better oxygen reduction reaction (ORR) performances (onset potential: 0.81 V vs reversible hydrogen electrode (RHE), electron transfer number: 3.9 at 0.5 V vs RHE) than graphitic carbon nitride (g-C N ) and the ordered mesoporous C N . The study on the mechanism of ORR suggests that nitrogen atoms in the tetrazine moiety of the ordered mesoporous C N act as active sites for its improved ORR activity.
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http://dx.doi.org/10.1002/smll.201903572DOI Listing
March 2020

Amine Functionalized Metal-Organic Framework Coordinated with Transition Metal Ions: d-d Transition Enhanced Optical Absorption and Role of Transition Metal Sites on Solar Light Driven H Production.

Small 2020 Mar 14;16(12):e1902990. Epub 2019 Nov 14.

SRM Research Institute and Department of Chemistry, SRM Institute of Science and Technology, Chennai, 603203, Tamil Nadu, India.

Design and development of efficient photocatalysts for H production from water and sunlight have gained significant attention as the solar assisted approach is considered to be a promising approach for the generation of clean fuel. However, the poor charge carrier separation and light harvesting ability of existing photocatalysts limits the efficiency of photoconversion of water. In this work, the synthesis of transition metal ions (M = Co , Cu , and Ni ) coordinated with Ti-metal organic frameworks (Ti-MOFs) through a simple post-synthetic coordination method for efficient solar light-driven H production is reported. Notably, coordination of M ions with Ti-MOF significantly improves the optical absorption by d-d transitions and the multimetal sites facilitate the fast charge carrier separation, thereby enhancing the solar light-driven H production activity. Very interestingly, the rate of solar light-driven H production is varied with respect to different metal ions coordination due to the position of d-d bands absorption in the solar spectrum, and the complexing tendency of M ions with sacrificial electron donors. A maximum solar H production rate of 1583.55 µmol h g is achieved with a Cu coordinated Ti-MOF, which is ≈13 fold higher than that of the pristine Ti-MOF.
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http://dx.doi.org/10.1002/smll.201902990DOI Listing
March 2020

Confinement-Induced Giant Spin-Orbit-Coupled Magnetic Moment of Co Nanoclusters in TiO Films.

ACS Appl Mater Interfaces 2019 Nov 11;11(46):43781-43788. Epub 2019 Nov 11.

Global Innovative Center for Advanced Nanomaterials, School of Engineering , University of Newcastle , Callaghan , NSW 2308 , Australia.

High magnetization materials are in great demand for the fabrication of advanced multifunctional magnetic devices. Notwithstanding this demand, the development of new materials with these attributes has been relatively slow. In this work, we propose a new strategy to achieve high magnetic moments above room temperature. Our material engineering approach invoked the embedding of magnetic nanoclusters in an oxide matrix. By precisely controlling pulsed laser deposition parameters, Co nanoclusters are formed in a 5 at % Co-TiO film. The presence of these nanoclusters was confirmed using transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray absorption fine structure. The film exhibits a very high saturation magnetization of 99 emu/cm. Detailed studies using X-ray magnetic circular dichroism confirm that Co has an enhanced magnetic moment of 3.5 μ/atom, while the Ti and O also contribute to the magnetic moments. First-principles calculations supported our hypothesis that the metallic Co nanoclusters surrounded by a TiO matrix can exhibit both large spin and orbital moments. Moreover, a quantum confinement effect results in a high Curie temperature for the embedded Co nanoclusters. These findings reveal that 1-2 nm nanoclusters that are quantum confined can exhibit very large magnetic moments above room temperature, representing a promising advance for the design of new high magnetization materials.
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http://dx.doi.org/10.1021/acsami.9b15823DOI Listing
November 2019

Mixed Copper/Copper-Oxide Anchored Mesoporous Fullerene Nanohybrids as Superior Electrocatalysts toward Oxygen Reduction Reaction.

Small 2020 Mar 24;16(12):e1903937. Epub 2019 Oct 24.

Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, 2308, New South Wales, Australia.

Developing a highly active, stable, and efficient non-noble metal-free functional electrocatalyst to supplant the benchmark Pt/C-based catalysts in practical fuel cell applications remains a stupendous challenge. A rational strategy is developed to directly anchor highly active and dispersed copper (Cu) nanospecies on mesoporous fullerenes (referred to as Cu-MFC ) toward enhancing oxygen reduction reaction (ORR) electrocatalysis. The preparation of Cu-MFC involves i) the synthesis of ordered MFC via the prevalent nanohard templating technique and ii) the postfunctionalization of MFC with finely distributed Cu nanospecies through incipient wet impregnation. The concurrence of Cu and cuprous oxide nanoparticles in the as-developed Cu-MFC samples through relevant material characterizations is affirmed. The optimized ORR catalyst, Cu(15%)-MFC , exhibits superior electrocatalytic ORR characteristics with an onset potential of 0.860 vs reversible hydrogen electrode, diffusion-limiting current density (-5.183 mA cm ), improved stability, and tolerance to methanol crossover along with a high selectivity (four-electron transfer). This enhanced ORR performance can be attributed to the rapid mass transfer and abundant active sites owing to the synergistic coupling effects arising from the mixed copper nanospecies and the fullerene framework.
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http://dx.doi.org/10.1002/smll.201903937DOI Listing
March 2020

Nanostructured Carbon Nitrides for CO Capture and Conversion.

Adv Mater 2020 May 14;32(18):e1904635. Epub 2019 Oct 14.

Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment (FEBE), The University of Newcastle, Callaghan, NSW, 2308, Australia.

Carbon nitride (CN), a 2D material composed of only carbon (C) and nitrogen (N), which are linked by strong covalent bonds, has been used as a metal-devoid and visible-light-active photocatalyst owing to its magnificent optoelectronic and physicochemical properties including suitable bandgap, adjustable energy-band positions, tailor-made surface functionalities, low cost, metal-free nature, and high thermal, chemical, and mechanical stabilities. CN-based materials possess a lot of advantages over conventional metal-based inorganic photocatalysts including ease of synthesis and processing, versatile functionalization or doping, flexibility for surface engineering, low cost, sustainability, and recyclability without any leaching of toxic metals from photocorrosion. Carbon nitrides and their hybrid materials have emerged as attractive candidates for CO capture and its reduction into clean and green low-carbon fuels and valuable chemical feedstock by using sustainable and intermittent renewable energy sources of sunlight and electricity through the heterogeneous photo(electro)catalysis. Here, the latest research results in this field are summarized, including implementation of novel functionalized nanostructured CNs and their hybrid heterostructures in meeting the stringent requirements to raise the efficiency of the CO reduction process by using state-of-the-art photocatalysis, electrocatalysis, photoelectrocatalysis, and feedstock reactions. The research in this field is primarily focused on advancement in the synthesis of nanostructured and functionalized CN-based hybrid heterostructured materials. More importantly, the recent past has seen a surge in studies focusing significantly on exploring the mechanism of their application perspectives, which include the behavior of the materials for the absorption of light, charge separation, and pathways for the transport of CO during the reduction process.
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http://dx.doi.org/10.1002/adma.201904635DOI Listing
May 2020

The Supramolecular Self-Assembly of Aminoglycoside Antibiotics and their Applications.

ChemistryOpen 2019 Sep 26;8(9):1154-1166. Epub 2019 Aug 26.

School of Chemical Sciences Goa University Taleigao Plateau Goa 403 206 INDIA.

Aminoglycosides, a class of antibiotics that includes gentamicin, kanamycin, neomycin, streptomycin, tobramycin and apramycin, are derived from various species. Despite the significant increase in the antibacterial resistant pathogens, aminoglycosides remain an important class of antimicrobial drugs due to their unique chemical structure which offers a broad spectrum of activity. The modification of antibiotics and their subsequent use in supramolecular chemistry is rarely reported. Given the importance of aminoglycosides, here we give a brief overview on the modification of 4,5- and 4,6-disubstituted deoxystreptamine classes of aminoglycosides through supramolecular chemistry and their potential for real world applications. We also make the case that the work in this area is gaining momentum, and there are significant opportunities to meet the challenges of modern antibiotics through the modification of aminoglycosides by harnessing the advantages of supramolecular chemistry.
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http://dx.doi.org/10.1002/open.201900193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6718072PMC
September 2019

High Coercivity and Magnetization in WSe by Codoping Co and Nb.

Small 2020 Mar 22;16(12):e1903173. Epub 2019 Aug 22.

Global Innovative Centre for Advanced Nanomaterials, School of Engineering, The University of Newcastle, Callaghan, NSW, 2308, Australia.

Introducing ferromagnetism in transition metal dichalcogenides has attracted lots of attention due to the possible applications in spintronics devices. Generally, single magnetic element doping is used to introduce magnetism. However, mostly, weak ferromagnetism is observed. In this work, codoping of two kinds of transition metals (Nb and Co) into WSe is used to study its magnetic properties. In detail, single crystal WSe is codoped with 4 at% Co and various concentrations of Nb by employing the physical ion implantation method. Raman, X-ray diffraction and X-ray photoelectron spectroscopy results reveal the effective substitutional doping of implanted elements (Co and Nb). Magnetic measurements illustrate that both un-doped and 4 at% Co doped WSe show weak ferromagnetism whereas magnetization is strongly enhanced when Co and Nb are codoped into WSe . The magnetization is comparable with a ferromagnet, which may be attributed to Co, Nb doping and defects. In addition, a large coercivity of ≈1.2 kOe is observed in the 1 at% Nb-4 at% Co codoped WSe sample, which may be ascribed to the combined effect of doping-induced stress, defect-dictated pinning and anisotropy of NbSe bond owing to the charge transfer between Nb and Se ions.
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http://dx.doi.org/10.1002/smll.201903173DOI Listing
March 2020

Sulfur-Doped Mesoporous Carbon Nitride with an Ordered Porous Structure for Sodium-Ion Batteries.

ACS Appl Mater Interfaces 2019 Jul 15;11(30):27192-27199. Epub 2019 Jul 15.

Global Innovative Center for Advanced Nanomaterials (GICAN), School of Engineering Faculty of Engineering and Built Environment , The University of Newcastle , Callaghan , New South Wales 2308 , Australia.

Mesoporous carbon nitride (MCN) with well-ordered porous structures is a promising anode material for secondary ion batteries owing to their unique physico- and electrochemical properties. However, the practical application of these MCNs in sodium-ion batteries (SIBs) is still limited because of their confined interlayer distance, which results in restricted accommodation of Na ions inside the lattice. Here, we report on the synthesis of highly ordered sulfur-doped MCN (S-MCN) through a hard template approach by employing dithiooxamide (DTO) as a single molecular precursor containing carbon, nitrogen, and sulfur elements. The interlayer distance of carbon nitride is significantly expanded upon the introduction of larger S ions on the MCN lattice, which enables high capability of Na ion accommodation. We also demonstrate through the first-principles density functional theory calculation that the present S-MCN is highly optimized not only for the chemical structure but also for uptaking abundant Na ions with high adsorption energy. The specific discharge capacity of SIBs appears to be remarkably enhanced for S-MCN (304.2 mA h g) compared to the nonporous S-CN (167.9 mA h g) and g-CN (5.4 mA h g), highlighting the pivotal roles of the highly ordered mesoporous structure and S-doping in enhancing the electrochemical functionality of carbon nitride as an anode material for SIBs.
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http://dx.doi.org/10.1021/acsami.9b07657DOI Listing
July 2019

Characterization and Hydrogen Storage Performance of Halloysite Nanotubes.

J Nanosci Nanotechnol 2019 12;19(12):7892-7898

Global Innovative Center for Advanced Nanomaterials, Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, New South Wales 2308, Australia.

Here we report on the structural characterization and the hydrogen storage performance of naturally derived halloysite nanotubes (HNTs). HNTs were mined from different deposits in Australia and purified with different processes including crushing, blunging, reblunging, sedimentation and filtration. The clay materials were characterized by different techniques such as powder XRD, TGA, XPS, FTIR spectroscopy, SEM, TEM, and N₂ sorption. Characterization results revealed that they are highly porous in nature with tubular morphology and exhibited excellent thermal stability. Among the halloysite materials studied, HNT1 which is having higher halloysite content and less kaolinite exhibited hydrogen uptake of 0.5 wt.% at 1 bar and -196 °C, which is increased to 1.33 wt.% when the pressure raised to 48 bar. High hydrogen uptake was linked with the high surface area, hollow tubular aluminosilicate structure and the large interlayer spacing of the HNTs as they favour physisorption of hydrogen. It was also demonstrated that HNT1 is considered to be better material than some of the materials reported so far in terms of their cost-effectiveness and environmental safety for the hydrogen storage.
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http://dx.doi.org/10.1166/jnn.2019.16751DOI Listing
December 2019

Highly Crystalline Mesoporous Phosphotungstic Acid: A High-Performance Electrode Material for Energy-Storage Applications.

Angew Chem Int Ed Engl 2019 Aug 1;58(32):10849-10854. Epub 2019 Jul 1.

Global Innovative Center for Advanced Nanomaterials (GICAN), School of Engineering, Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia.

Heteropoly acids (HPAs) are unique materials with interesting properties, including high acidity and proton conductivity. However, their low specific surface area and high solubility in polar solvents make them unattractive for catalytic or energy applications. This obstacle can be overcome by creating nanoporosity within the HPA. We synthesized mesoporous phosphotungstic acid (mPTA) with a spherical morphology through the self-assembly of phosphotungstic acid (PTA) with a polymeric surfactant as stabilized by KCl and hydrothermal treatment. The mPTA nanostructures had a surface area of 93 m  g and a pore size of 4 nm. Their high thermal stability (ca. 450 °C) and lack of solubility in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte are beneficial for lithium-ion batteries (LIBs). Optimized mPTA showed a reversible capacity of 872 mAh g at 0.1 A g even after 100 cycles for LIBs, as attributed to a super-reduced state of HPA and the storage of Li ions within the mesochannels of mPTA.
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http://dx.doi.org/10.1002/anie.201901224DOI Listing
August 2019

Freestanding Borophene and Its Hybrids.

Adv Mater 2019 Jul 1;31(27):e1900353. Epub 2019 May 1.

Global Innovative Center for Advanced Nanomaterials (GICAN), Faculty of Engineering and Built Environment, The University of Newcastle, Callaghan, NSW, 2308, Australia.

Borophene, an elemental metallic Dirac material is predicted to have unprecedented mechanical and electronic character. Need of substrate and ultrahigh vacuum conditions for deposition of borophene restricts its large-scale applications and significantly hampers the advancement of research on borophene. Herein, a facile and large-scale synthesis of freestanding atomic sheets of borophene through a novel liquid-phase exfoliation and the reduction of borophene oxide is demonstrated. Electron microscopy confirms the presence of β , X , and their intermediate phases of borophene; X-ray photoelectron spectroscopy, and scanning tunneling microscopy, corroborated with density functional theory band structure calculations, validate the phase purity and the metallic nature. Borophene with excellent anchoring capabilities is used for sensing of light, gas, molecules, and strain. Hybrids of borophene as well as that of reduced borophene oxide with other 2D materials are synthesized, and the predicted superior performance in energy storage is explored. The specific capacity of borophene oxide is observed to be ≈4941 mAh g , which significantly exceeds that of existing 2D materials and their hybrids. These freestanding borophene materials and their hybrids will create a huge breakthrough in the field of 2D materials and could help to develop future generations of devices and emerging applications.
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http://dx.doi.org/10.1002/adma.201900353DOI Listing
July 2019

A novel geopolymer route to porous carbon: high CO adsorption capacity.

Chem Commun (Camb) 2019 Mar;55(22):3266-3269

Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 03760, Republic of Korea.

The nanostructure and morphology of mesoporous carbon obtained from a newly designed porous geopolymer template were characterized by low-voltage high-resolution scanning electron microscopy. The present porous carbon exhibited a large specific surface area and pore volume, resulting in a high CO2 uptake capacity.
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http://dx.doi.org/10.1039/c9cc00232dDOI Listing
March 2019