Publications by authors named "Haomin Xu"

17 Publications

  • Page 1 of 1

Zero-Valent Palladium Single-Atoms Catalysts Confined in Black Phosphorus for Efficient Semi-Hydrogenation.

Adv Mater 2021 Sep 23;33(35):e2008471. Epub 2021 Jul 23.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.

Single-atom catalysts (SACs) represent a new frontier in heterogeneous catalysis due to their remarkable catalytic properties and maximized atomic utilization. However, single atoms often bond to the support with polarized electron density and thus exhibit a high valence state, limiting their catalytic scopes in many chemical transformations. Here, it is demonstrated that 2D black phosphorus (BP) acts as giant phosphorus (P) ligand to confine a high density of single atoms (e.g., Pd , Pt ) via atomic layer deposition. Unlike other 2D materials, BP with relatively low electronegativity and buckled structure favors the strong confinement of robust zero-valent palladium SACs in the vacancy site. Metallic Pd /BP SAC shows a highly selective semi-hydrogenation of phenylacetylene toward styrene, distinct from metallic Pd nanoparticles that facilitate the formation of fully hydrogenated products. Density functional theory calculations reveal that Pd atom forms covalent-like bonding with adjacent P atoms, wherein H atoms tend to adsorb, aiding the dissociative adsorption of H . Zero-valent Pd in the confined space favors a larger energy gain for the synthesis of partially hydrogenated product over the fully hydrogenated one. This work provides a new route toward the synthesis of zero-valent SACs on BP for organic transformations.
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http://dx.doi.org/10.1002/adma.202008471DOI Listing
September 2021

Facile Production of Phosphorene Nanoribbons towards Application in Lithium Metal Battery.

Adv Mater 2021 Sep 22;33(35):e2102083. Epub 2021 Jul 22.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.

Like phosphorene, phosphorene nanoribbon (PNR) promises exotic properties but unzipping phosphorene into edge-defined PNR is non-trivial because of uncontrolled cutting of phosphorene along random directions. Here a facile electrochemical strategy to fabricate zigzag-edged PNRs in high yield (>80%) is reported. The presence of chemically active zigzag edges in PNR allows it to spontaneously react with Li to form a Li ion conducting Li P phase, which can be used as a protective layer on Li metal anode in lithium metal batteries (LMBs). PNR protective layer prevents the parasitic reaction between lithium metal and electrolyte and promotes Li ion diffusion kinetics, enabling homogenous Li ion flux and long-time cycling stability up to 1100 h at a current density of 1 mA cm . LiFePO |PNR-Li full-cell batteries with an areal capacity of 2 mAh cm , a lean electrolyte (20 µl mAh ) and a negative/positive (N/P) electrodes ratio of 3.5 can be stably cycled over 100 cycles.
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http://dx.doi.org/10.1002/adma.202102083DOI Listing
September 2021

Ordered clustering of single atomic Te vacancies in atomically thin PtTe promotes hydrogen evolution catalysis.

Nat Commun 2021 Apr 21;12(1):2351. Epub 2021 Apr 21.

SZU-NUS Collaborative Center and International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, Guangdong, China.

Exposing and stabilizing undercoordinated platinum (Pt) sites and therefore optimizing their adsorption to reactive intermediates offers a desirable strategy to develop highly efficient Pt-based electrocatalysts. However, preparation of atomically controllable Pt-based model catalysts to understand the correlation between electronic structure, adsorption energy, and catalytic properties of atomic Pt sites is still challenging. Herein we report the atomically thin two-dimensional PtTe nanosheets with well-dispersed single atomic Te vacancies (Te-SAVs) and atomically well-defined undercoordinated Pt sites as a model electrocatalyst. A controlled thermal treatment drives the migration of the Te-SAVs to form thermodynamically stabilized, ordered Te-SAV clusters, which decreases both the density of states of undercoordinated Pt sites around the Fermi level and the interacting orbital volume of Pt sites. As a result, the binding strength of atomically defined Pt active sites to H intermediates is effectively reduced, which renders PtTe nanosheets highly active and stable in hydrogen evolution reaction.
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http://dx.doi.org/10.1038/s41467-021-22681-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8060321PMC
April 2021

Tuning the Spin Density of Cobalt Single-Atom Catalysts for Efficient Oxygen Evolution.

ACS Nano 2021 Apr 31;15(4):7105-7113. Epub 2021 Mar 31.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.

Single-atom catalysts (SACs) with magnetic elements as the active center have been widely exploited for efficient electrochemical conversions. Understanding the catalytic role of spin, and thus modulating the spin density of a single-atom center, is of profound fundamental interest and technological impact. Here, we synthesized ferromagnetic single Co atom catalysts on TaS monolayers (Co/TaS) as a model system to explore the spin-activity correlation for the oxygen evolution reaction (OER). A single Co atom adsorbed at the hollow site (Co) with spin-polarized electronic states serves as the active site for OER, whose spin density can be regulated by its neighboring single Co site tuning the Co loading. Both experimental and theoretical results reveal the spin density-dependent OER activity that an optimal spin density of Co can be achieved with a neighboring hetero-single Co site (substitution of Ta by Co) for a superior OER performance, in contrast to a homo-single Co site, which creates an excessive spin density over vicinal Co. An optimized spin density of Co results in an optimal binding energy of oxygen species for the OER. Establishing the spin-activity correlation in SACs may create a descriptor for designing efficient magnetic SACs for renewable energy conversions.
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http://dx.doi.org/10.1021/acsnano.1c00251DOI Listing
April 2021

Dense-Stacking Porous Conjugated Polymer as Reactive-Type Host for High-Performance Lithium Sulfur Batteries.

Angew Chem Int Ed Engl 2021 May 6;60(20):11359-11369. Epub 2021 Apr 6.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.

Commercialization of the lithium-sulfur battery is hampered by bottlenecks like low sulfur loading, high cathode porosity, uncontrollable Li S deposition and sluggish kinetics of Li S activation. Herein, we developed a densely stacked redox-active hexaazatrinaphthylene (HATN) polymer with a surface area of 302 m  g and a very high bulk density of ca. 1.60 g cm . Uniquely, HATN polymer has a similar redox potential window to S, which facilitates the binding of Li S and its transformation chemistry within the bulky polymer host, leading to fast Li S/S kinetics. The compact polymer/S electrode presents a high sulfur loading of ca. 15 mg  cm (200-μm thickness) with a low cathode porosity of 41 %. It delivers a high areal capacity of ca. 14 mAh cm and good cycling stability (200 cycles) at electrolyte-sulfur (E/S) ratio of 5 μL mg . The assembled pouch cell delivers a cell-level high energy density of 303 Wh kg and 392 Wh L .
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http://dx.doi.org/10.1002/anie.202016240DOI Listing
May 2021

Electrochemically Exfoliated Platinum Dichalcogenide Atomic Layers for High-Performance Air-Stable Infrared Photodetectors.

ACS Appl Mater Interfaces 2021 Feb 11;13(7):8518-8527. Epub 2021 Feb 11.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.

Platinum dichalcogenide (PtX), an emergent group-10 transition metal dichalcogenide (TMD) has shown great potential in infrared photonic and optoelectronic applications due to its layer-dependent electronic structure with potentially suitable bandgap. However, a scalable synthesis of PtSe and PtTe atomic layers with controlled thickness still represents a major challenge in this field because of the strong interlayer interactions. Herein, we develop a facile cathodic exfoliation approach for the synthesis of solution-processable high-quality PtSe and PtTe atomic layers for high-performance infrared (IR) photodetection. As-exfoliated PtSe and PtTe bilayer exhibit an excellent photoresponsivity of 72 and 1620 mA W at zero gate voltage under a 1540 nm laser illumination, respectively, approximately several orders of magnitude higher than that of the majority of IR photodetectors based on graphene, TMDs, and black phosphorus. In addition, our PtSe and PtTe bilayer device also shows a decent specific detectivity of beyond 10 Jones with remarkable air-stability (>several months), outperforming the mechanically exfoliated counterparts under the laser illumination with a similar wavelength. Moreover, a high yield of PtSe and PtTe atomic layers dispersed in solution also allows for a facile fabrication of air-stable wafer-scale IR photodetector. This work demonstrates a new route for the synthesis of solution-processable layered materials with the narrow bandgap for the infrared optoelectronic applications.
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http://dx.doi.org/10.1021/acsami.0c20535DOI Listing
February 2021

Printable two-dimensional superconducting monolayers.

Nat Mater 2021 Feb 26;20(2):181-187. Epub 2020 Oct 26.

Department of Chemistry, National University of Singapore, Singapore, Singapore.

Two-dimensional superconductor (2DSC) monolayers with non-centrosymmetry exhibit unconventional Ising pair superconductivity and an enhanced upper critical field beyond the Pauli paramagnetic limit, driving intense research interest. However, they are often susceptible to structural disorder and environmental oxidation, which destroy electronic coherence and provide technical challenges in the creation of artificial van der Waals heterostructures (vdWHs) for devices. Herein, we report a general and scalable synthesis of highly crystalline 2DSC monolayers via a mild electrochemical exfoliation method using flexible organic ammonium cations solvated with neutral solvent molecules as co-intercalants. Using NbSe as a model system, we achieved a high yield (>75%) of large-sized single-crystal monolayers up to 300 µm. The as-fabricated, twisted NbSe vdWHs demonstrate high stability, good interfacial properties and a critical current that is modulated by magnetic field when one flux quantum fits to an integer number of moiré cells. Additionally, formulated 2DSC inks can be exploited to fabricate wafer-scale 2D superconducting wire arrays and three-dimensional superconducting composites with desirable morphologies.
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http://dx.doi.org/10.1038/s41563-020-00831-1DOI Listing
February 2021

Atomically-precise dopant-controlled single cluster catalysis for electrochemical nitrogen reduction.

Nat Commun 2020 Sep 1;11(1):4389. Epub 2020 Sep 1.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.

The ability to precisely engineer the doping of sub-nanometer bimetallic clusters offers exciting opportunities for tailoring their catalytic performance with atomic accuracy. However, the fabrication of singly dispersed bimetallic cluster catalysts with atomic-level control of dopants has been a long-standing challenge. Herein, we report a strategy for the controllable synthesis of a precisely doped single cluster catalyst consisting of partially ligand-enveloped AuPt clusters supported on defective graphene. This creates a bimetal single cluster catalyst (AuPt/G) with exceptional activity for electrochemical nitrogen (N) reduction. Our mechanistic study reveals that each N molecule is activated in the confined region between cluster and graphene. The heteroatom dopant plays an indispensable role in the activation of N via an enhanced back donation of electrons to the N LUMO. Moreover, besides the heteroatom Pt, the catalytic performance of single cluster catalyst can be further tuned by using Pd in place of Pt as the dopant.
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http://dx.doi.org/10.1038/s41467-020-18080-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463028PMC
September 2020

Imprinting Ferromagnetism and Superconductivity in Single Atomic Layers of Molecular Superlattices.

Adv Mater 2020 Jun 17;32(25):e1907645. Epub 2020 May 17.

Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.

Ferromagnetism and superconductivity are two antagonistic phenomena since ferromagnetic exchange fields tend to destroy singlet Cooper pairs. Reconciliation of these two competing phases has been achieved in vertically stacked heterostructures where these two orders are confined in different layers. However, controllable integration of these two phases in one atomic layer is a longstanding challenge. Here, an interlayer-space-confined chemical design (ICCD) is reported for the synthesis of dilute single-atom-doped TaS molecular superlattice, whereby ferromagnetism is observed in the superconducting TaS layers. The intercalation of 2H-TaS crystal with bulky organic ammonium molecule expands its van der Waals gap for single-atom doping via co-intercalated cobalt ions, resulting in the formation of quasi-monolayer Co-doped TaS superlattices. Isolated Co atoms are decorated in the basal plane of the TaS via substituting the Ta atom or anchoring at a hollow site, wherein the orbital-selected p-d hybridization between Co and neighboring Ta and S atoms induces local magnetic moments with strong ferromagnetic coupling. This ICCD approach can be applied to various metal ions, enabling the synthesis of a series of crystal-size TaS molecular superlattices.
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http://dx.doi.org/10.1002/adma.201907645DOI Listing
June 2020

A Graphene-Supported Single-Atom FeN Catalytic Site for Efficient Electrochemical CO Reduction.

Angew Chem Int Ed Engl 2019 Oct 9;58(42):14871-14876. Epub 2019 Sep 9.

Institutes of Physical Science and Information Technology, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Anhui University, Hefei, 230601, P. R. China.

Electrochemical conversion of CO into valued products is one of the most important issues but remains a great challenge in chemistry. Herein, we report a novel synthetic approach involving prolonged thermal pyrolysis of hemin and melamine molecules on graphene for the fabrication of a robust and efficient single-iron-atom electrocatalyst for electrochemical CO reduction. The single-atom catalyst exhibits high Faradaic efficiency (ca. 97.0 %) for CO production at a low overpotential of 0.35 V, outperforming all Fe-N-C-based catalysts. The remarkable performance for CO -to-CO conversion can be attributed to the presence of highly efficient singly dispersed FeN active sites supported on N-doped graphene with an additional axial ligand coordinated to FeN . DFT calculations revealed that the axial pyrrolic nitrogen ligand of the FeN site further depletes the electron density of Fe 3d orbitals and thus reduces the Fe-CO π back-donation, thus enabling the rapid desorption of CO and high selectivity for CO production.
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http://dx.doi.org/10.1002/anie.201906079DOI Listing
October 2019

One-Pot Synthesis of BiCuSO Nanosheets under Ambient Atmosphere as Broadband Spectrum Photocatalyst.

Nanomaterials (Basel) 2019 Apr 3;9(4). Epub 2019 Apr 3.

State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.

Cuprous based chalcogenides have attracted intensive research interest due to the potential applications in solar energy conversion. However, typical fabrications of these compounds are often carried out under severe conditions, such as inert gas protection, high vacuum, and/or extreme high temperature. Here we reported a one-pot process for cuprous based chalcogenides synthesis in aqueous solution. A strategy for BiCuSO nanosheets fabrication without toxic chemicals or rigorous reagents at pretty low temperatures under an ambient atmosphere was established, with the practicality of morphology controlling and the compatibility of multifarious precursors. Platelike BiCuSO with a thickness range from several to hundreds nanometers are fabricated by adjusting the alkali concentration, reaction time, and temperature. The positive effect of alkali hydroxide concentration is proposed cautiously based on the experimental results. The photocatalytic activities of BiCuSO nanosheet under UV, visible, and near-infrared irradiation were also investigated. BiCuSO obtained at room temperature with a thickness of 4.5 nm showed the most impressive efficiency to decompose organic contaminants. Our research presented a new way for cuprous sulfides fabrication, and might open up a new vista for large-scale synthesis of cuprous based materials as promising broadband spectrum light-absorbing materials.
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http://dx.doi.org/10.3390/nano9040540DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523219PMC
April 2019

Synthesis and Broadband Spectra Photocatalytic Properties of Bi₂O₂(CO₃)S.

Materials (Basel) 2018 May 14;11(5). Epub 2018 May 14.

State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.

High efficiency photocatalyst Bi₂O₂(CO₃)S was synthesized conveniently with chemical bath precipitation using Bi₂O₂CO₃ as the precursor. The microstructures of the samples are systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and UV-Vis spectroscopy; the optical and photocatalytic properties are carefully tested as well. The content of , which was tuned through the controlling of the precipitation process, was verified to have an intense effect over the photocatalytic properties. A nearly saturated ratio and the best photocatalytic performance were observed in specimens with the most content. Our study reveals that, with negligible influence of the morphology and crystal structure, Bi₂O₂(CO₃)S possessed a broadened optical absorption regionfromultraviolet to visible light, and enhanced photocatalytic activity in comparison to precursor Bi₂O₂CO₃ in photocatalytic degradation of Congo Red aqueous solution.
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http://dx.doi.org/10.3390/ma11050791DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5978168PMC
May 2018

Highly (001)-Textured Tetragonal BiFeO Film and Its Photoelectrochemical Behaviors Tuned by Magnetic Field.

ACS Appl Mater Interfaces 2017 Sep 25;9(35):30127-30132. Epub 2017 Aug 25.

State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University , Beijing 100084, People's Republic of China.

Highly (001)-textured BiFeO film in tetragonal phase (T-BFO) with a giant c/a ratio was first obtained on quartz/polycrystalline ITO substrate. Our results indicate that the polycrystalline ITO layer with small surface roughness is a critical point to control the growth of T-BFO structure. It should be ascribed to the fact that a Bi-rich phase interlayer (∼5 nm) could be formed on ITO, which acted as a crystal seed layer and thus induced the growth of (001)-textured T-BFO structure. The observed weak room temperature ferromagnetism should be attributed to Fe valence change. Open circuit potential measurements under 360 μW/cm full spectra irradiation show that the open circuit potential and the lifetime of photo-induced carriers increased under applied magnetic field, which reveals that the applied magnetic field can manipulate the photo electrochemical behaviors of BFO film. Our findings offer a simple way to fabricate highly (001)-textured T-BFO film, which make it desirable to obtain extensive applications for these oriented BFO films.
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http://dx.doi.org/10.1021/acsami.7b07644DOI Listing
September 2017

Highly selective and active CO reduction electrocatalysts based on cobalt phthalocyanine/carbon nanotube hybrid structures.

Nat Commun 2017 03 8;8:14675. Epub 2017 Mar 8.

Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.

Electrochemical reduction of carbon dioxide with renewable energy is a sustainable way of producing carbon-neutral fuels. However, developing active, selective and stable electrocatalysts is challenging and entails material structure design and tailoring across a range of length scales. Here we report a cobalt-phthalocyanine-based high-performance carbon dioxide reduction electrocatalyst material developed with a combined nanoscale and molecular approach. On the nanoscale, cobalt phthalocyanine (CoPc) molecules are uniformly anchored on carbon nanotubes to afford substantially increased current density, improved selectivity for carbon monoxide, and enhanced durability. On the molecular level, the catalytic performance is further enhanced by introducing cyano groups to the CoPc molecule. The resulting hybrid catalyst exhibits >95% Faradaic efficiency for carbon monoxide production in a wide potential range and extraordinary catalytic activity with a current density of 15.0 mA cm and a turnover frequency of 4.1 s at the overpotential of 0.52 V in a near-neutral aqueous solution.
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http://dx.doi.org/10.1038/ncomms14675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5344970PMC
March 2017

Bi(1-x)La(x)CuSeO as New Tunable Full Solar Light Active Photocatalysts.

Sci Rep 2016 Apr 20;6:24620. Epub 2016 Apr 20.

State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People's Republic of China.

Photocatalysis is attracting enormous interest driven by the great promise of addressing current energy and environmental crises by converting solar light directly into chemical energy. However, efficiently harvesting solar energy for photocatalysis remains a pressing challenge, and the charge kinetics and mechanism of the photocatalytic process is far from being well understood. Here we report a new full solar spectrum driven photocatalyst in the system of a layered oxyselenide BiCuSeO with good photocatalytic activity for degradation of organic pollutants and chemical stability under light irradiation, and the photocatalytic performance of BiCuSeO can be further improved by band gap engineering with introduction of La. Our measurements and density-functional-theory calculations reveal that the effective mass and mobility of the carriers in BiCuSeO can be tuned by the La-doping, which are responsible for the tunable photocatalytic activity. Our findings may offer new perspectives for understanding the mechanism of photocatalysis through modulating the charge mobility and the effective mass of carriers and provide a guidance for designing efficient photocatalyts.
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http://dx.doi.org/10.1038/srep24620DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4837348PMC
April 2016

Photochemical fate of beta-blockers in NOM enriched waters.

Sci Total Environ 2012 Jun 12;426:289-95. Epub 2012 Apr 12.

Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, Irvine, CA 92697-2175, USA.

Beta-blockers, prescribed for the treatment of high blood pressure and for long-term use after a heart attack, have been detected in surface and ground waters. This study examines the photochemical fate of three beta-blockers, atenolol, metoprolol, and nadolol. Hydrolysis accounted for minor losses of these beta-blockers in the pH range 4-10. The rate of direct photolysis at pH 7 in a solar simulator varied from 6.1 to 8.9h(-1) at pH 7. However, the addition of a natural organic matter (NOM) isolate enhanced the photochemical loss of all three compounds. Indirect photochemical fate, generally described by reactions with hydroxyl radical (OH) and singlet oxygen ((1)ΔO(2)), and, the direct reaction with the triplet excited state, (3)NOM(⁎), also varied but collectively appeared to be the major loss factor. Bimolecular reaction rate constants of the three beta-blockers with (1)ΔO(2) and OH were measured and accounted for 0.02-0.04% and 7.2-38.9% of their loss, respectively. These data suggest that the (3)NOM(⁎) contributed 50.6-85.4%. Experiments with various (3)NOM(⁎) quenchers supported the hypothesis that it was singly the most important reaction. Atenolol was chosen for more detailed investigation, with the photoproducts identified by LC-MS analysis. The results suggested that electron-transfer could be an important mechanism in photochemical fate of beta-blockers in the presence of NOM.
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http://dx.doi.org/10.1016/j.scitotenv.2012.03.031DOI Listing
June 2012

Photosensitized degradation of amoxicillin in natural organic matter isolate solutions.

Water Res 2011 Jan 17;45(2):632-8. Epub 2010 Aug 17.

Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175, USA.

Amoxicillin is a widely used antibiotic and has been detected in natural waters. Its environmental fate is in part determined by hydrolysis, and, direct and indirect photolysis. The hydrolysis rate in distilled water and water to which five different isolated of dissolved organic matter (DOM) was added, were evaluated. In the five different DOM solutions hydrolysis accounted for 5-18% loss of amoxicillin. Direct and indirect photolysis rates were determined using a solar simulator and it appeared that indirect photolysis was the dominant loss mechanism. Direct photolysis, in a solar simulator, accounted for 6-21% loss of amoxicillin in the simulated natural waters. The steady-state concentrations of singlet oxygen, (1)ΔO(2) (∼10(-13) M) and hydroxyl radical, •OH (∼10(-17) M) were obtained in aqueous solutions of five different dissolved organic matter samples using a solar simulator. The bimolecular reaction rate constant of (1)ΔO(2) with amoxicillin was measured in the different solutions, k(ΔO(2)) = 1.44 × 10(4) M(-1) s(-1). The sunlight mediated amoxicillin loss rate with (1)ΔO(2) (∼10(-9) s(-1)), and with •OH (∼10(-7) s(-1)), were also determined for the different samples of DOM. While (1)ΔO(2) only accounted for 0.03-0.08% of the total loss rate, the hydroxyl radical contributed 10-22%. It appears that the direct reaction of singlet and triplet excited state DOM ((3)DOM(∗)) with amoxicillin accounts for 48-74% of the loss of amoxicillin. Furthermore, the pseudo first-order photodegradation rate showed a positive correlation with the sorption of amoxicillin to DOM, which further supported the assumption that excited state DOM∗ plays a key role in the photochemical transformation of amoxicillin in natural waters. This is the first study to report the relative contribution of all five processes to the fate of amoxicillin in aqueous solution.
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http://dx.doi.org/10.1016/j.watres.2010.08.024DOI Listing
January 2011
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