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  1. Abstract

    Photo‐responsive semiconductors can facilitate nitrogen activation and ammonia production, but the high recombination rate of photogenerated carriers represents a significant barrier. Ferroelectric photocatalysts show great promise in overcoming this challenge. Herein, by adopting a low‐temperature hydrothermal procedure with varying concentrations of glyoxal as the reducing agent, oxygen vacancies (Vo) are effectively produced on the surface of ferroelectric SrBi4Ti4O15(SBTO) nanosheets, which leads to a considerable increase in photocatalytic activity toward nitrogen fixation under simulated solar light with an ammonia production rate of 53.41 µmol g−1h−1, without the need of sacrificial agents or photosensitizers. This is ascribed to oxygen vacancies that markedly enhance the self‐polarization and internal electric field of ferroelectric SBTO, and hence, facilitate the separation of photogenerated charge carriers and light trapping as well as N2adsorption and activation, as compared to pristine SBTO. Consistent results are obtained in theoretical studies. Results from this study highlight the significance of surface oxygen vacancies in enhancing the performance of photocatalytic nitrogen fixation by ferroelectric catalysts.

     
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  2. Abstract

    Copper compounds have been extensively investigated for diverse applications. However, studies of cuprous hydroxide (CuOH) have been scarce due to structural metastability. Herein, a facile, wet‐chemistry procedure is reported for the preparation of stable CuOH nanostructures via deliberate functionalization with select organic ligands, such as acetylene and mercapto derivatives. The resulting nanostructures are found to exhibit a nanoribbon morphology consisting of small nanocrystals embedded within a largely amorphous nanosheet‐like scaffold. The acetylene derivatives are found to anchor onto the CuOH forming CuC linkages, whereas CuS interfacial bonds are formed with the mercapto ligands. Effective electronic coupling occurs at the ligand‐core interface in the former, in contrast to mostly non‐conjugated interfacial bonds in the latter, as manifested in spectroscopic measurements and confirmed in theoretical studies based on first principles calculations. Notably, the acetylene‐capped CuOH nanostructures exhibit markedly enhanced photodynamic activity in the inhibition of bacteria growth, as compared to the mercapto‐capped counterparts due to a reduced material bandgap and effective photocatalytic generation of reactive oxygen species. Results from this study demonstrate that deliberate structural engineering with select organic ligands is an effective strategy in the stabilization and functionalization of CuOH nanostructures, a critical first step in exploring their diverse applications.

     
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  3. Abstract

    Conventional β‐lactam antibiotics are resisted by bacteria at an increasing rate, prompting studies into the development of alternate antibiotic agents. In this personal account, we summarize recent progress in the design and engineering of graphene oxide quantum dot‐based nanomaterials as potent antimicrobial agents. Specifically, we examine the impacts of chemical reduction on the antimicrobial activity of graphene oxide quantum dots, and enhancement of the bactericidal performance by the formation of nanocomposites with metal oxide nanoparticles, within the context of photodynamic generation of reactive oxygen species. A perspective is also included where the promises and challenges are highlighted in the development of high‐performance antimicrobial agents based on graphene derivatives.

     
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  4. Abstract

    Single‐atom catalysts (SACs) have been attracting extensive interest in the electrocatalytic production of hydrogen peroxide by oxygen reduction reaction (ORR). This is due to the maximal efficiency of atom utilization and intimate interaction of the metal centers with the supporting matrix that may be exploited for deliberate manipulation of the electrocatalytic activity and selectivity, in comparison with the conventional nanoparticle counterparts. Herein, we summarize recent progress of the design and engineering of SACs towards ORR for H2O2generation, based on both noble and non‐noble metals. We conclude the review with a perspective highlighting the promises and challenges involved in future research.

     
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  5. Abstract

    Janus nanoparticles capped with a hydrophobic and hydrophilic hemisphere of mercapto ligands can self‐assemble into hollow, emulsion‐like nanostructures in controlled media. As the nanoparticle emulsions are chiroptically active exhibiting a plasmonic circular dichroism absorption in the visible range, they can be exploited as a unique chiral nanoreactor by selective encapsulation ofd‐enantiomer into the water phase of the water‐in‐oil emulsions for directional functionalization of the nanoparticles and endow the resulting nanoparticles with select chirality. This is demonstrated in the present study with gold Janus nanoparticles functionalized with (hydrophobic) hexanethiolates and (hydrophilic) 3‐mercapto‐1,2‐propandiol, andd,l‐cysteine is used as the molecular probe. Experimental results demonstrate thatd‐cysteine is the preferred enantiomers entrapped within the nanoparticle emulsions, where the ensuing ligand exchange reaction is initially confined to the hydrophilic face of the Janus nanoparticles. This suggests that with a deliberate control of the reaction time, chiral Janus nanoparticles can be readily prepared by ligand exchange reactions even with a racemic mixture of ligands.

     
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  6. Controlling microbial proliferation in water systems, including wastewater, recreational water, and drinking water, is essential to societal health. Microbial inactivation through electrochemically generated reactive species (RS) mediated pathways provides an effective route toward this microbial control. Herein we provide an overview of recent progress toward electrocatalytic generation of RS and their application in water disinfection, with a focus on the selective production of RS, the microorganism interactions with RS (including both RS mechanisms of action and innate microorganism responses to RS), and practical implementation of electrochemically generated RS for microbial inactivation. The article is concluded with a perspective where the challenges and opportunities of RS‐based electrochemical disinfection of water are highlighted, along with possible future research directions. 
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