Publications by authors named "Wenchao Peng"

46 Publications

Nitrogen-carbon materials base on pyrolytic graphene hydrogel for oxygen reduction.

J Colloid Interface Sci 2021 Nov 8;602:274-281. Epub 2021 Jun 8.

Lab of Advanced Nano-structures & Transfer Processes, Department of Chemical Engineering, Tianjin University, Tianjin 300354, China; Chemistry and Chemical Engineering Guangdong Laboratory, Shantou 515031 China. Electronic address:

Hypothesis: Oxygen reduction reaction (ORR) has played a significant role in the utilization of energy nowadays. Nitrogen-doped carbon materials are seen as promising catalysts for ORR, so it is of great significance in studying the functions of different nitrogen moieties.

Experiments: The graphene hydrogel-based nitrogen-arbon materials (GH N-C) were fabricated by first obtaining a gel through hydrothermal treatment using graphene oxide (GO) as precursor, and then calcined in an ammonia atmosphere at different temperatures to form N-doped graphitized materials with divers nitrogen configuration.

Findings: GH N-C materials with tunable nitrogen configuration were synthesized by a two-step method base on graphene hydrogel. Benefiting from the 3D hydrogel structure, rich defects and optimized chemical properties, GH N-C-900 prepared by NH pyrolysis at 900 °C exhibits an excellent electrocatalytic performance toward ORR, with the onset potential of 0.947 ± 0.013 V versus RHE, half-wave potential of 0.830 ± 0.010 V versus RHE, electron transfer number of 3.61-3.99, along as methanol tolerance and superior long-term stability. Comprehensive studies have shown that there is a positive correlation between the total amount of pyrrolic-N and quaternary-N and the catalytic performance of ORR.
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http://dx.doi.org/10.1016/j.jcis.2021.06.036DOI Listing
November 2021

Bimetallic ZIF-Derived Co/N-Codoped Porous Carbon Supported Ruthenium Catalysts for Highly Efficient Hydrogen Evolution Reaction.

Nanomaterials (Basel) 2021 May 6;11(5). Epub 2021 May 6.

Lab of Advanced Nano-Structure and Transfer Process, Department of Chemical Engineering, Tianjin University, Tianjin 300354, China.

Exploring the economical, powerful, and durable electrocatalysts for hydrogen evolution reaction (HER) is highly required for practical application. Herein, nanoclusters-decorated ruthenium, cobalt nanoparticles, and nitrogen codoped porous carbon ([email protected]) are prepared with bimetallic zeolite imidazole frameworks (ZnCo-ZIF) as the precursor. Thus, the prepared [email protected] catalyst with a low Ru loading of 3.13 wt% exhibits impressive HER catalytic behavior in 1 M KOH, with an overpotential of only 30 mV at the current density of 10 mA cm, Tafel slope as low as 32.1 mV dec, and superior stability for long-time running with a commercial 20 wt% Pt/C. The excellent electrocatalytic properties are primarily by virtue of the highly specific surface area and porosity of carbon support, uniformly dispersed Ru active species, and rapid reaction kinetics of the interaction between Ru and O.
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http://dx.doi.org/10.3390/nano11051228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8148513PMC
May 2021

Facile synthesis of iron oxide supported on porous nitrogen doped carbon for catalytic oxidation.

Sci Total Environ 2021 Sep 24;785:147296. Epub 2021 Apr 24.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300050, China. Electronic address:

Iron oxide (FeO) supported on porous nitrogen doped carbon is synthesized by a facile pyrolysis method. SiO and NaNO are used as the template and activation agent respectively for porous structure generation and large specific surface area (SSA) creation. The obtained materials show superior catalytic oxidation ability and can activate peroxymonosulfate (PMS) in a wide pH range (3-9) to degrade organic pollutants. The degradation process is a two-stage reaction, including a rapid initial decay and a following slow reaction stage. According to the free radical quenching experiments, electron paramagnetic resonance (EPR) spectroscopy analysis, and electrochemical tests, the superoxide radical (O) and singlet oxygen (O) are proved to play crucial roles in organics degradation. The high SSA (773 m g), abundant of structural defects, and synergistic effect between FeO and the nitrogen doped carbon are the key factors for the enhanced activity. The catalysts in this study can be synthesized easily and contain no toxic metals, thus should have great potential in the wastewater remediation.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147296DOI Listing
September 2021

A palladium doped 1T-phase molybdenum disulfide-black phosphorene two-dimensional van der Waals heterostructure for visible-light enhanced electrocatalytic hydrogen evolution.

Nanoscale 2021 Mar 16;13(11):5892-5900. Epub 2021 Mar 16.

Faculty of Chemical Engineering, Yunnan Provincial Key Laboratory of Energy Saving in Phosphorus Chemical Engineering and New Phosphorus Materials, Kunming University of Science and Technology, Kunming 650500, Yunnan, China.

The electrocatalytic hydrogen evolution reaction (HER) is a green chemistry route for sustainable energy production. Compared to 2H-phase molybdenum disulfide (MoS), the 1T-phase MoS (1T-MoS) has higher theoretical activity and faster charge transfer kinetics, but the HER performance of 1T-MoS is commonly hindered by limited active edge/defect as well as poor structural stability. Herein, we synthesize a well-defined 2D vdW heterostructure composed of Pd doped 1T-MoS and black phosphorus (BP) nanosheets via electrostatic self-assembly. The spontaneous Pd doping under mild reaction conditions could introduce catalytically active sulfur vacancies in MoS without triggering a wide range of 1T to 2H phase transformation. The hetero-interfacial charge transfer from BP to Pd-1T-MoS can effectively improve the intrinsic activity of Pd-1T-MoS with a relatively low S vacancy concentration and simultaneously stabilize the 1T-phase structure. Due to the wide-range light absorption of BP nanosheets and the high carrier mobilities of 2D materials, the HER activity of the obtained Pd-1T-MoS/BP could be further enhanced under ≥420 nm visible light illumination.
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http://dx.doi.org/10.1039/d0nr09133bDOI Listing
March 2021

Synergistic Effect of N-Doped sp Carbon and Porous Structure in Graphene Gels toward Selective Oxidation of C-H Bond.

ACS Appl Mater Interfaces 2021 Mar 11;13(11):13087-13096. Epub 2021 Mar 11.

School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People's Republic of China.

N-doped carbon materials represent a type of metal-free catalyst for diverse organic synthetic reactions. However, single N-doped carbon materials perform insufficiently in the selective oxidation reaction of C-H bond compared with metal catalysts or multielement co-doped materials. There are a few reports on the application of three-dimensional (3D) carbon materials in such a reaction. Besides, the relationship between the well-developed porous structures, heteroatom doping, and their catalytic performance is unclear. In this study, 3D porous N-doped graphene aerogel catalysts with high activity and selectivity for the C-H bond oxidation under mild reaction conditions have been synthesized through a two-step method. Systematic studies on the dosage of N sources, pyrolysis temperature, and their influences on the catalytic performances have been evolved. Moreover, solid evidence of the synergistic effect of sp C atoms adjacent to the N atoms and porous structure promoting the performance has been provided in this work.
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http://dx.doi.org/10.1021/acsami.0c21177DOI Listing
March 2021

Preparation of Hollow Cobalt-Iron Phosphides Nanospheres by Controllable Atom Migration for Enhanced Water Oxidation and Splitting.

Small 2021 Apr 9;17(13):e2007858. Epub 2021 Mar 9.

School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, P. R. China.

Transition metal phosphides (TMPs), especially the dual-metal TMPs, are highly active non-precious metal oxygen evolution reaction (OER) electrocatalysts. Herein, an interesting atom migration phenomenon induced by Kirkendall effect is reported for the preparation of cobalt-iron (Co-Fe) phosphides by the direct phosphorization of Co-Fe alloys. The compositions and distributions of the Co and Fe phosphides phases on the surfaces of the electrocatalysts can be readily controlled by Co Fe alloys precursors and the phosphorization process with interesting atom migration phenomenon. The optimized Co Fe phosphides exhibit a low overpotential of 225 mV at 10 mA cm in 1 m KOH alkaline media, with a small Tafel slope of 37.88 mV dec and excellent durability. It only requires a voltage of 1.56 V to drive the current density of 10 mA cm when used as both anode and cathode for overall water splitting. This work opens a new strategy to controllable preparation of dual-metal TMPs with designed phosphides active sites for enhanced OER and overall water splitting.
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http://dx.doi.org/10.1002/smll.202007858DOI Listing
April 2021

Predicting Daily Dry Matter Intake Using Feed Intake of First Two Hours after Feeding in Mid and Late Lactation Dairy Cows with Fed Ration Three Times per Day.

Animals (Basel) 2021 Jan 6;11(1). Epub 2021 Jan 6.

Institute of Dairy Science, MoE Key Laboratory of Molecular Animal Nutrition, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China.

The objective of this study was to evaluate the feasibility of using the dry matter intake of first 2 h after feeding (DMI-2h), body weight (BW), and milk yield to estimate daily DMI in mid and late lactating dairy cows with fed ration three times per day. Our dataset included 2840 individual observations from 76 cows enrolled in two studies, of which 2259 observations served as development dataset (DDS) from 54 cows and 581 observations acted as the validation dataset (VDS) from 22 cows. The descriptive statistics of these variables were 26.0 ± 2.77 kg/day (mean ± standard deviation) of DMI, 14.9 ± 3.68 kg/day of DMI-2h, 35.0 ± 5.48 kg/day of milk yield, and 636 ± 82.6 kg/day of BW in DDS and 23.2 ± 4.72 kg/day of DMI, 12.6 ± 4.08 kg/day of DMI-2h, 30.4 ± 5.85 kg/day of milk yield, and 597 ± 63.7 kg/day of BW in VDS, respectively. A multiple regression analysis was conducted using the REG procedure of SAS to develop the forecasting models for DMI. The proposed prediction equation was: DMI (kg/day) = 8.499 + 0.2725 × DMI-2h (kg/day) + 0.2132 × Milk yield (kg/day) + 0.0095 × BW (kg/day) (R = 0.46, mean bias = 0 kg/day, RMSPE = 1.26 kg/day). Moreover, when compared with the prediction equation for DMI in Nutrient Requirements of Dairy Cattle (2001) using the independent dataset (VDS), our proposed model shows higher R (0.22 vs. 0.07) and smaller mean bias (-0.10 vs. 1.52 kg/day) and RMSPE (1.77 vs. 2.34 kg/day). Overall, we constructed a feasible forecasting model with better precision and accuracy in predicting daily DMI of dairy cows in mid and late lactation when fed ration three times per day.
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http://dx.doi.org/10.3390/ani11010104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7825592PMC
January 2021

Easily Regenerated CuO/γ-AlO for Persulfate-Based Catalytic Oxidation: Insights into the Deactivation and Regeneration Mechanism.

ACS Appl Mater Interfaces 2021 Jan 5;13(2):2630-2641. Epub 2021 Jan 5.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China.

In this work, γ-AlO-supported CuO (-CuO/AlO) materials are successfully synthesized using a novel impregnation-precipitation-decomposition method. The obtained -CuO/AlO catalyst shows excellent catalytic activities for bisphenol A (BPA) degradation with sodium persulfate (PDS) as an oxidant. Radical quenching tests and electron paramagnetic resonance (EPR) studies indicate that PDS activation is a combined mechanism involving both free radical and nonfree radical pathways. In a continuous large-scale degradation process, about 1.78 L of 20 ppm BPA can be completely removed within 480 min. Although -CuO/AlO can be deactivated after several reaction cycles, the catalytic activity can be regenerated after simple aerobic calcination. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirm that the deactivation of -CuO/AlO should be attributed to the conversion of Cu(II) to Cu(I). The aerobic calcination could oxidize Cu(I) back to Cu(II), thus recovering the catalytic activity. In addition, the density functional technology (DFT) and temperature-programmed oxidation (TPD) results reveal that γ-AlO can not only serve as a carrier to anchor the CuO particles but also can adsorb and activate PDS by introducing more basic sites on the surface. -CuO/AlO has high activity and can be regenerated easily, thus having great potential applications for wastewater treatment.
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http://dx.doi.org/10.1021/acsami.0c19013DOI Listing
January 2021

Bamboo-like nitrogen-doped carbon nanotubes on iron mesh for electrochemically-assisted catalytic oxidation.

J Hazard Mater 2021 Apr 29;408:124899. Epub 2020 Dec 29.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China. Electronic address:

In this study, bamboo-like nitrogen-doped carbon nanotubes (BN-CNTs) are successfully deposited on etched iron mesh (d-Fe) using chemical vapor deposition (CVD) method with acetonitrile as precursor. The acidic etching process is necessary for the special BN-CNTs structure formation by exposing more Fe sites. The BN-CNTs/d-Fe is then evaluated for the electrochemically-assisted PMS activation to degrade phenol. Under cyclic voltammetry (CV, 0-1 V vs. RHE) assistant, 20 ppm phenol can be degraded in 30 min with a rate constant of 0.2837 min, ~78 times more than that without CV. Some Fe species in the catalyst will be reduced at the initial stage, a two-step pseudo-first-order kinetic is thus used for the degradation curves fitting. Both the structure defects and doped nitrogen atoms are responsible for the high catalytic activity of BN-CNTs. According to the quenching tests, both radical and non-radical processes are present for PMS activation, thus obtaining enhanced organics removal efficiency. The electrochemically assistant could enhance the PMS adsorption on the electrode as well as electrons transfer between Fe and PMS, thus increasing the PMS activation efficiency. The utilization of earth-abundant Fe mesh for the fabricating free-standing electrodes provide a potential low-cost and effective strategy of waste water remediation.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124899DOI Listing
April 2021

Surfactant-Free Synthesis of Ultrafine Pt Nanoparticles on MoS Nanosheets as Bifunctional Catalysts for the Hydrodeoxygenation of Bio-Oil.

Langmuir 2020 12 23;36(48):14710-14716. Epub 2020 Nov 23.

School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People's Republic of China.

Hydrodeoxygenation (HDO) of bio-oil is a crucial step for improving the bio-fuel quality, but developing highly dispersed Pt-based catalysts with high selectivity for target alkanes remains a great challenge. This study presents a fast surfactant-free method to prepare the MoS-supported Pt catalyst for HDO. Ultrafine Pt nanoparticles with sizes of <5 nm can be readily grown on chemically exfoliated MoS nanosheets (NSs) via the direct microwave-assisted thermal reduction. The obtained Pt NPs/MoS composites show excellent catalytic performance in the conversion of palmitic acid, and the best selectivity (also the yield) of hexadecane and pentadecane is 80.56 and 19.43%, respectively.
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http://dx.doi.org/10.1021/acs.langmuir.0c02613DOI Listing
December 2020

Thermal removal of partial nitrogen atoms in N-doped graphene for enhanced catalytic oxidation.

J Colloid Interface Sci 2021 Mar 20;585:640-648. Epub 2020 Oct 20.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300050, China. Electronic address:

Carbon materials are effective catalysts to activate peroxymonosulfate (PMS) for organic pollutant degradation. Both nitrogen doping and structural defects could enhance their catalytic performance for PMS activation. In this study, nitrogen-doped graphene (NG) is first synthesized by the calcination of graphene oxide (GO) with ammonium nitrate (NHNO). The obtained NG is then annealed further at a higher temperature under a N atmosphere to remove partially doped N atoms and create new structural defects. The obtained defective nitrogen-doped graphene (D-NG) can activate PMS for bisphenol A (BPA) degradation more effectively. Different annealing temperatures from 850 to 1150 °C are investigated, and D-NG synthesized at 1050 °C exhibits the highest activity. The enhanced catalytic performance is proposed to originate from the synergistic effect between doped N atoms and created structural defects. According to radical quenching, electron paramagnetic resonance (EPR), and electrochemical results, both radical and nonradical pathways are present during PMS activation, and the nonradical pathway plays the dominant role. This study provides a facile method for metal-free catalyst synthesis, which also enriches the synergistic mechanism between doped N and structural defects and thus should have great potential in wastewater remediation.
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http://dx.doi.org/10.1016/j.jcis.2020.10.043DOI Listing
March 2021

Topochemical synthesis of low-dimensional nanomaterials.

Nanoscale 2020 Nov;12(43):21971-21987

School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072, People's Republic of China.

Over the past several decades, nanomaterials have been extensively studied owing to having a series of unique physical and chemical properties that exceed those of conventional bulk materials. Researchers have developed a lot of strategies for the synthesis of low-dimensional nanomaterials. Among them, topochemical synthesis has attracted increasing attention because it can provide more new nanomaterials by improving and upgrading inexpensive and accessible nanomaterials. In this review, we summarize and analyze many existing topochemical synthesis methods, including selective etching, liquid phase reactions, high-temperature atmosphere reactions, electrochemically assisted methods, etc. The future direction of topochemical synthesis is also proposed.
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http://dx.doi.org/10.1039/d0nr04763eDOI Listing
November 2020

Aminated N-doped graphene hydrogel for long-term catalytic oxidation in strong acidic environment.

J Hazard Mater 2021 Jan 22;401:123742. Epub 2020 Aug 22.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300050, China. Electronic address:

Metal-based catalysts in advanced oxidation processes (AOPs) are not stable under strong acidic condition due to the remarkable leaching, which will also lead to a secondary pollution. In this study, an aminated N-doped graphene hydrogel (ANGH) is synthesized from graphene oxide and ethylenediamine (EDA) via an in-situ hydrothermal process. The ANGH shows a free-standing structure and has high catalytic activity especially in phenol degradation under strong-acidic condition because of a non-radical dominated mechanism determined in this process. On the large scale, a longer lifetime of ∼1700 min for ANGH is obtained under strong-acidic condition on a dynamic amplifying device, 2.9 times longer than that at neutral condition. It is proposed that amine N can be protected by hydrogen ions from being oxidized, thus leading to the better stability. Meanwhile, the active sites of ANGH can transform from N containing groups into oxygenous groups, and the deactivated material can be reutilized 10 times for rhodamine B degradation on a large scale. The ANGH synthesized facilely and could be recycled repeatedly, which is also very stable in the strong acidic environment, thus should have great potential in wastewater remediation.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123742DOI Listing
January 2021

Synthesis of nitrogen and sulfur doped graphene on graphite foam for electro-catalytic phenol degradation and water splitting.

J Colloid Interface Sci 2021 Feb 23;583:139-148. Epub 2020 Sep 23.

School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia.

A rational design of electrode materials with both high electron conductivity and abundant of catalytic sites is essential for high-performance electrochemical reactions. Herein, a nitrogen and sulfur co-doped graphene (SNG) anchored on the interconnected conductive graphite foam (GF) is fabricated via drop-casting and in situ annealing. The SNG flakes are tightly immobilized on the GF surface, which can provide fast electron transfer rate and large electrolyte/electrode interfaces. The [email protected] composite can be directly used as a free-standing electrode for electro-catalytic degradation of organic pollutants and overall water splitting. [email protected] significantly enhanced the electrochemical activation of peroxymonosulfate (PMS) for catalytic oxidation. During the oxygen evolution reaction (OER), the [email protected] exhibits an initial overpotential of 330 mV vs. RHE at 10 mA cm with a Tafel slope of 149 mV dec in 1 M KOH, which outperforms most of the reported metal-free catalysts. The density functional theory calculations are also used to unveil the S, N dual doping effects of carbon materials and their synergy in carbocatalysis. This study dedicates to developing multi-functional carbocatalysts for environmental and energy applications, and enables insights into carbocatalysis in electrochemistry.
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http://dx.doi.org/10.1016/j.jcis.2020.09.053DOI Listing
February 2021

A near-infrared light-mediated antimicrobial based on Ag/TiCT for effective synergetic antibacterial applications.

Nanoscale 2020 Oct;12(37):19129-19141

School of Chemical Engineering and Technology, Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (MOE), Tianjin University, Tianjin 300072, People's Republic of China.

Designing antimicrobials with high efficiency and long-term antibacterial activity is an imperative issue. We found that the antimicrobial effect of Ti3C2Tx and Ag/Ti3C2Tx could be significantly strengthened upon near-infrared light exposure. The synergistic antibacterial mode of the photothermal bactericidal effect and intrinsic bacterial activity have been revealed, which confirms that the Ti3C2Tx MXene is an excellent near-infrared light-mediated nanoplatform for antibacterial applications. To further test the antibacterial effect in practical applications, Ag/Ti3C2Tx embedded hydrogels were used as wound dressings in a wound model experiment. They exhibit outstanding bacterial inhibition and wound healing performance with near-infrared light exposure. This work inspires us to explore the MXene-based photothermal platform in terms of antibacterial application.
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http://dx.doi.org/10.1039/d0nr04925eDOI Listing
October 2020

Increasing the heteroatoms doping percentages of graphene by porous engineering for enhanced electrocatalytic activities.

J Colloid Interface Sci 2020 Oct 24;577:101-108. Epub 2020 May 24.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China. Electronic address:

Graphene based materials are considered as promising catalysts towards electro-catalytic water splitting. Heteroatoms doping and structure defects creation in graphene matrix could enhance the electro-catalytic activity effectively. In this work, a nitrogen and sulfur co-doped graphene is synthesized and then activated by KOH to involve a porous structure. The atomic ratios of doped heteroatoms are found increased surprisingly. This should be due to the better thermal stability of doped heteroatoms compared with the origin carbon atoms. More carbon atoms will be removed, thus leading to the increased heteroatoms doping percentages. The increased surface area, larger heteroatoms ratios, and abundant structure defects result in the improved catalytic activity towards electrochemical oxygen evolution reaction (OER). The overpotential for OER could achieve as early as 281 mV vs. RHE at 10 mA·cm in 1 M KOH, better than most of the metal free catalysts. The obtained sample is active over a wide pH range in electrochemical hydrogen evolution reaction (HER), thus could be used as bifunctional materials for water splitting. This work provides a simple and low-cost approach to increase the ratios of doped heteroatoms, and thus should have great potential both for carbon materials synthesis and hydrogen production.
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http://dx.doi.org/10.1016/j.jcis.2020.05.089DOI Listing
October 2020

Defected graphene as effective co-catalyst of CdS for enhanced photocatalytic activities.

Environ Sci Pollut Res Int 2020 Jul 7;27(21):26810-26816. Epub 2020 May 7.

School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300050, China.

Synthesis of highly efficient photocatalysts for energy and environment catalysis is still a big challenge in the materials field. Cadmium sulfide (CdS) is a promising visible light-driven photocatalyst, which can be composited with co-catalysts to increase its photo-activity and stability. In this study, a kind of graphene material with abundant structure defects (D-rGO) is synthesized by a two-step annealing process with nitrogen-doped rGO (N-rGO) as an intermediate. The high-temperature annealing could remove the doped heteroatoms to form structure defects with five or seven carbon atoms. The D-rGO is then used as co-catalyst for the modification of CdS nanoparticles, and enhanced photocatalytic activities could be obtained. A large hydrogen evolution rate of 102.7 μmol h g is achieved, which is also effective for 4-nitrophenol reduction with a rate constant of 0.168 min. The novel CdS/D-rGO composite contains no noble metals and could be used as multi-functional photocatalysts, thus should has great potential in the photocatalysis field.
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http://dx.doi.org/10.1007/s11356-020-09066-8DOI Listing
July 2020

Decorated nickel phosphide nanoparticles with nitrogen and phosphorus co-doped porous carbon for enhanced electrochemical water splitting.

J Colloid Interface Sci 2020 May 11;567:393-401. Epub 2020 Feb 11.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300050, China. Electronic address:

A novel free-standing electrode consisting of nickel phosphide (NiP) nanoparticles on nitrogen and phosphorus co-doped porous carbon (NPC) are synthesized on carbon cloth (CC). Polyaniline (PANI) and nickel (Ni) are sequentially electro-deposited on the surface of CC, which are then transformed into NPC and NiP by an in-situ carbonization-phosphorization combined process. The electrode surface is distributed with large amounts of uniform macropores, which could expose more active sites and enhance the interfacial exchange with the electrolyte. The [email protected]@CC electrode delivers early overpotentials of 92 and 280 mV vs. Reversible Hydrogen Electrode (RHE) at 10 mA cm for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline condition, respectively. The electrolytic cell with [email protected]@CC electrode both as anode and cathode can achieve 10 mA cm at a small bias of 1.54 V for the overall water splitting. Density functional theory (DFT) calculation indicates that combination with NiP and NPC can decrease Gibbs free energy for H* adsorption (ΔG) and increase charge density on the interface, thus could lead to the enhanced activity for water splitting. The free-standing and noble-metal free [email protected]@CC electrode is stable, highly active and cost effective, thus have great potential for the hydrogen production.
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http://dx.doi.org/10.1016/j.jcis.2020.02.033DOI Listing
May 2020

High-performance porous graphene from synergetic nitrogen doping and physical activation for advanced nonradical oxidation.

J Hazard Mater 2020 01 13;381:121010. Epub 2019 Aug 13.

School of Chemical Engineering, The University of Adelaide, Adelaide SA 5005, Australia.

Porous nitrogen-doped reduced graphene oxide (NRGO) is successfully synthesized from graphene oxide via the combination of CO activation and nitrogen doping with ammonia. The performances of the carbon materials are evaluated by catalytic activation of perroxymonosulfate (PMS) for phenol degradation. The effect of the treatment sequence of CO activation and nitrogen doping on the catalytic activity of the derived product is investigated. The material obtained by CO activation-nitrogen doping (P-NRGO) shows better activity than the one obtained from nitrogen doping-CO activation (N-PRGO). The activation mechanisms are also investigated by radical scavenging test, and the P-NRGO/PMS system is unveiled to rely on the nonradical oxidation pathway. The turnover frequencies (TOFs) of these RGOs are also calculated, and the P-NRGO has the largest TOF of 58.39. Based on the analysis of synthesis method and catalytic activity, it is proposed that new catalytic sites are generated on P-NRGO. Density functional theory (DFT) calculations also illustrated that the most reactive sites are the structure vacancies with two nitrogen atoms, which is consistent with the results. The conclusion in this study provides new insights into the synergistic effect of N-doping and structural defects of carbon materials and the induced nonradical pathway in advanced oxidation.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121010DOI Listing
January 2020

Bifunctional Graphene-Based Metal-Free Catalysts for Oxidative Coupling of Amines.

ACS Appl Mater Interfaces 2019 Sep 20;11(35):31844-31850. Epub 2019 Aug 20.

Lab of Advanced Nano Structures & Transfer Processes, Department of Chemical Engineering , Tianjin University , Tianjin 300354 , P. R. China.

Graphene oxide (GO), an emerging material ornamented with oxygen-containing functional groups, is becoming a promising alternative for various applications. The piranha solution treatment of GO can increase oxygen-containing functional groups and result in improved graphene oxide (IGO), as well as restore the functional groups lost because of the reaction. It is found that GO can oxidize the amine to the corresponding imine in the absence of oxygen and a catalyst, and the obtained IGO even shows higher activity. In addition, the piranha solution can partially restore the reactivity of GO after the reaction. The different roles of oxygen-containing functional groups in the oxidative coupling reaction are investigated. A possible reaction mechanism for the oxidation of benzylamine to -benzylidene benzylamine is also proposed.
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http://dx.doi.org/10.1021/acsami.9b08741DOI Listing
September 2019

Butyllithium-Treated TiCT MXene with Excellent Pseudocapacitor Performance.

ACS Nano 2019 Aug 5;13(8):9449-9456. Epub 2019 Aug 5.

School of School of Chemical Engineering and Technology , Tianjin University , Tianjin 300072 , China.

MXenes, a family of two-dimensional (2D) transition-metal carbide and nitride materials, are supposed to be promising pseudocapacitive materials because of their high electronic conductivity and hydrophilic surfaces. MXenes, prepared by removing the "A" elements of their corresponding MAX phases by hydrofluoric acid (HF) or LiF-HCl etching, possess abundant terminal groups like -F, -OH, and -O groups. It has been proven that the MXenes with fewer -F terminal groups and more -O groups showed a higher pseudocapacitor performance. In organic reactions, -OH and -X (X = halogen) groups could turn to ether groups in strong nucleophilic reagent. Inspired by that, herein, we report an -butyllithium-treated method to turn the -F and -OH terminal groups to -O groups on the TiCT MXenes. Two types of TiCT MXenes prepared by either HF or LiF-HCl etching were systematically investigated, and a comparison with the traditional KOH/NaOH/LiOH-treated method was also carried out. It is found that most of the -F terminal groups on the TiCT MXenes can be successfully removed by -butyllithium, and abundant -O terminal groups were formed. The -butyllithium-treated TiCT MXenes show promising applications in high-performance pseudocapacitors. A record high capacitance of 523 F g at 2 mV s was obtained for the -butyllithium-treated TiCT MXenes, and 96% capacity can remain even after 10 000 cycles.
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http://dx.doi.org/10.1021/acsnano.9b04301DOI Listing
August 2019

Heterostructure engineering of Co-doped MoS coupled with MoCT MXene for enhanced hydrogen evolution in alkaline media.

Nanoscale 2019 Jun;11(22):10992-11000

School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300072, China.

The hydrogen evolution reaction (HER) in alkaline media is key for the cathodic reaction of electrochemical water splitting, but it suffers sluggish kinetics due to the slow water dissociation process. Here, we present a simple strategy to enhance the HER activity in alkaline media by engineering Co-doped MoS2 coupled with Mo2CTx MXene. The improved HER activity might be ascribed to the synergistic regulation of water dissociation sites and electronic conductivity. Co doping could effectively regulate the electronic structure of MoS2 and further improve the intrinsic activity of the catalyst. Mo2CTx MXene served as both the active and conductive substrate to facilitate electron transfer. As a result, the Co-MoS2/Mo2CTx nanohybrids showed dramatically enhanced HER performance with a low overpotential of 112 mV at a current density of 10 mA cm-2 and exhibited excellent long-term stability in alkaline media.
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http://dx.doi.org/10.1039/c9nr02085cDOI Listing
June 2019

TiO nanorod arrays decorated with exfoliated WS nanosheets for enhanced photoelectrochemical water oxidation.

J Colloid Interface Sci 2019 Jun 14;545:282-288. Epub 2019 Mar 14.

State Key Laboratory of Chemical Engineering, School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin 300354, China. Electronic address:

A novel three-dimensional (3D) photoanode consisting of TiO nanorod arrays (TiO NAs) coated by exfoliated WS nanosheets was fabricated for enhanced photoelectrochemical water oxidation. Mixed phase WS nanosheets with 1 T percentage of 55% were exfoliated by the lithium insertion, which were then coated on the top of TiO NAs by a drop-casting method. By optimizing the loading amount of WS, a maximum photocurrent of ∼1.8 mA/cm could be obtained at +1.8 V vs. RHE under AM 1.5 irradiation (100 mW/cm), which is 2.3 times higher compared to the pure TiO NAs (0.8 mA/cm). The enhanced photo-activity should be attributed to the presence of the mixed phase WS nanosheets, which have excellent charge transport ability and can accept photogenerated holes for water oxidation.
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http://dx.doi.org/10.1016/j.jcis.2019.03.041DOI Listing
June 2019

Reversible intercalation and exfoliation of layered covalent triazine frameworks for enhanced lithium ion storage.

Chem Commun (Camb) 2019 Jan;55(10):1434-1437

Faculty of Chemical Engineering, The Higher Educational Key Laboratory for Phosphorus Chemical Engineering of Yunnan Province, Kunming University of Science and Technology, Kunming 650500, China.

We report that layered covalent triazine frameworks (CTF-1) can be rapidly and reversibly intercalated with either an oxidizing or a non-oxidizing acid based on the acid-base driven mechanism. The obtained CTF-1 intercalated compounds can be readily reacted with nitronium ions and spontaneously exfoliated into 1-2 layered functionalized CTF-1 nanosheets (f-CTF-1) with a high yield of 42%. The f-CTF-1 shows a 2.5 to 3.8 times increase in specific capacitance and much better rate performance when used as an LIB anode.
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http://dx.doi.org/10.1039/c8cc10262gDOI Listing
January 2019

3D self-supported Ni(PO)-MoO nanorods anchored on nickel foam for highly efficient overall water splitting.

Nanoscale 2018 Dec 27;10(47):22173-22179. Epub 2018 Nov 27.

Lab of Advanced Nano Structures & Transfer Processes, Department of Chemical Engineering, Tianjin University, Tianjin 300354, P. R. China.

Electrolyzing water as a sustainable energy source is a promising and appealing method to resolve the environmental crisis. Developing efficient and stable bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is crucial and challenging in the overall water splitting process. Herein, we report the synthesis of Ni(PO)-MoO nanorods anchored on nickel foam (Ni(PO)-MoO/NF) within a two-step strategy and their application as a bifunctional water splitting electrocatalyst. The results show that the optimal Ni(PO)-MoO/NF electrodes exhibit superior catalytic activity with robust durability and ultralow overpotentials of 86 mV for HER and 234 mV for OER to achieve 10 mA cm (η) in alkaline solution. The favorable performance of the obtained catalyst is attributed mainly to the synergetic effect between Ni(PO) and MoO, as well as the self-supporting porous conductive substrate. As a result, the integrated Ni(PO)-MoO/NF electrodes deliver η at a small potential of 1.47 V for overall water splitting, highlighting a promising application as a bifunctional electrocatalyst.
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http://dx.doi.org/10.1039/c8nr07577hDOI Listing
December 2018

Magnetic Au-Ag-γ-Fe₂O₃/rGO Nanocomposites as an Efficient Catalyst for the Reduction of 4-Nitrophenol.

Nanomaterials (Basel) 2018 Oct 25;8(11). Epub 2018 Oct 25.

Lab of Advanced Nano-structures & Transfer Processes, Department of Chemical Engineering, Tianjin University, Tianjin 300354, China.

In this paper, a facile route has been developed to prepare magnetic trimetallic Au-Ag-γ-Fe₂O₃/rGO nanocomposites. The impact of the preparation method (the intensity of reductant) on the catalytic performance was investigated. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The prepared nanocomposites show fine catalytic activity towards the reduction reaction of 4-nitrophenol (4-NP). The nanocomposites also have superparamagnetism at room temperature, which can be easily separated from the reaction systems by applying an external magnetic field.
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http://dx.doi.org/10.3390/nano8110877DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266811PMC
October 2018

Decoration of CuO photocathode with protective TiO and active WS layers for enhanced photoelectrochemical hydrogen evolution.

Nanotechnology 2018 Dec 1;29(50):505603. Epub 2018 Oct 1.

School of Chemical Engineering and Technology, Tianjin University, Tianjin 300050, People's Republic of China.

A CuO based multi-layered photocathode was fabricated with a layer-by-layer assembly method for enhanced photoelectrochemical (PEC) hydrogen evolution. Au was first electrodeposited on the fluorine-doped tin oxide glass to decrease the electrochemical impedance of the CuO photocathode. A layer of TiO was then coated to increase the light-to-electricity energy conversion efficiency and the chemical stability by forming a p-n junction with CuO. Exfoliated WS nanosheets obtained from lithium insertion were then coated as the electron acceptor to facilitate the hydrogen evolution. This photocathode is effective for PEC hydrogen evolution, and a photocurrent of -10 mA cm can be obtained at -0.33 V versus RHE in a phosphorus buffer (pH = 6.0) under visible light (λ ≥ 420 nm, 100 mW cm) on the optimized photocathode.
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http://dx.doi.org/10.1088/1361-6528/aae569DOI Listing
December 2018

Hierarchical Cobalt Borate/MXenes Hybrid with Extraordinary Electrocatalytic Performance in Oxygen Evolution Reaction.

ChemSusChem 2018 Nov 12;11(21):3758-3765. Epub 2018 Oct 12.

School of School of Chemical Engineering and Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, P.R. China.

Oxygen evolution reaction (OER) is a key reaction for many renewable energy storage and conversion techniques. Developing efficient non-precious metal-based electrocatalysts for OER has attracted increasing attention. Herein is reported a strategy to fabricate hierarchical cobalt borate/Ti C T MXene (Co-B /Ti C T ) hybrid through fast chemical reactions at room temperature. This interesting hierarchical structure of Co-B /Ti C T hybrid is beneficial for exposing more active sites, improving mass diffusion, and charge-transfer pathways for electrochemical reaction. Moreover, a strong interaction between Co-B and Ti C T ensures efficient charge transfer and facilitates the electrostatic attraction of more anionic intermediates for a fast redox process. Consequently, the hierarchical Co-B /Ti C T hybrid shows extraordinary OER catalytic activity to deliver a current density of 10 mA cm at an overpotential of 250 mV, and a Tafel slope of about 53 mV dec .
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http://dx.doi.org/10.1002/cssc.201802098DOI Listing
November 2018

Correction: TiCT nanosheets as photothermal agents for near-infrared responsive hydrogels.

Nanoscale 2018 09;10(36):17409

School of Chemical Engineering & Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, China.

Correction for 'Ti2C3Tx nanosheets as photothermal agents for near-infrared responsive hydrogels' by Changyu Yang et al., Nanoscale, 2018, 10, 15387-15392.
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http://dx.doi.org/10.1039/c8nr90190bDOI Listing
September 2018

TiCT nanosheets as photothermal agents for near-infrared responsive hydrogels.

Nanoscale 2018 Aug;10(32):15387-15392

School of Chemical Engineering & Technology, State Key Laboratory of Chemical Engineering, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin University, Tianjin, 300072, China.

Poly(N-isopropylacrylamide) (PNIPAM) is broadly applicable in many fields due to its temperature-induced phase transition property. Herein, a facile method to incorporate exfoliated Ti2C3Tx nanosheets in the PNIPAM network is reported. Due to compatibility, stability and photothermal properties of the incorporated Ti2C3Tx nanosheets, the obtained MXene/PNIPAM composite hydrogel shows excellent photothermal properties, expanding the pure thermal-responsive property of the PNIPAM hydrogel. Based on the smart composite hydrogel, remote light-control of the microfluidic pipeline is also demonstrated.
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http://dx.doi.org/10.1039/c8nr05301dDOI Listing
August 2018
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