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The electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3−) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3− to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen‐containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH‐neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3−. Herein, we constructed a Cu1‐Fe dual‐site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero‐valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3− removal efficiency of 94.8 % and NH3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L−1 NO3−−N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3− adsorption on Fe sites and strengthened water activation on single‐atom Cu sites, decreasing the energy barrier for the rate‐determining step of *NO‐to‐*NOH. This work develops a novel strategy of fabricating dual‐site catalysts to enhance the electrosynthesis of NH3 from NO3−, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction reaction (NO3RR) is able to convert nitrate (NO3−) into reusable ammonia (NH3), offering a green treatment and resource utilization strategy of nitrate wastewater and ammonia synthesis. The conversion of NO3− to NH3 undergoes water dissociation to generate active hydrogen atoms and nitrogen‐containing intermediates hydrogenation tandemly. The two relay processes compete for the same active sites, especially under pH‐neutral condition, resulting in the suboptimal efficiency and selectivity in the electrosynthesis of NH3 from NO3−. Herein, we constructed a Cu1‐Fe dual‐site catalyst by anchoring Cu single atoms on amorphous iron oxide shell of nanoscale zero‐valent iron (nZVI) for the electrochemical NO3RR, achieving an impressive NO3− removal efficiency of 94.8 % and NH3 selectivity of 99.2 % under neutral pH and nitrate concentration of 50 mg L−1 NO3−−N conditions, greatly surpassing the performance of nZVI counterpart. This superior performance can be attributed to the synergistic effect of enhanced NO3− adsorption on Fe sites and strengthened water activation on single‐atom Cu sites, decreasing the energy barrier for the rate‐determining step of *NO‐to‐*NOH. This work develops a novel strategy of fabricating dual‐site catalysts to enhance the electrosynthesis of NH3 from NO3−, and presents an environmentally sustainable approach for neutral nitrate wastewater treatment. [ABSTRACT FROM AUTHOR]

A robust electrocatalyst based on single iron atoms was developed for CO2 reduction with a high faradaic efficiency over 99.6%. The cathodic CO2 reduction was then coupled with anodic production of hypochlorite, and high energy efficiency (82%) with nearly 100% atom economy could be achieved in this model electrolysis system. [ABSTRACT FROM AUTHOR]

Organoarsenic compounds have been widely used as feed additives in livestock and poultry breeding. They are excreted in manure and thus cause environmental pollution. Moreover, organoarsenic compounds can be transformed into other arsenic species with higher toxicity. There is little knowledge on the transformation of organoarsenic compounds in the presence of iron species. Here, we studied the transformation of roxarsone (4-hydroxy-3-nitrophenylarsonic acid) in the presence of ferrous ion (Fe(II)) and tetrapolyphosphate. Various generated arsenic species were monitored. Results show that 94.8% of roxarsone was degraded within 30 min in 10 mmol L−1 Fe(II) and 50 mmol L−1 tetrapolyphosphate under air atmosphere. 70% of roxarsone arsenic was converted to As(V) species by hydroxyl radicals generated in the air system. Moreover, roxarsone is reductively transformed into other organoarsenic compounds, for example 4-hydroxy-3-aminophenylarsonic acid, by accepting electrons from the Fe(II)–tetrapolyphosphate complex. The toxicity and mobility of the generated inorganic or organic arsenic species are higher than those of roxarsone, which may induce serious environment and human health problems. [ABSTRACT FROM AUTHOR]

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Semiconductor photocatalysis is a trustworthy approach to harvest clean solar light for energy conversions, while state-of-the-art catalytic efficiencies are unsatisfactory because of the finite light response and/or recombination of robust charge carriers. Along with the development of modern material characterization techniques and electronic-structure computations, oxygen vacancies (OVs) on the surface of real photocatalysts, even in infinitesimal concentration, are found to play a more decisive role in determining the kinetics, energetics, and mechanisms of photocatalytic reactions. This Review endeavors to clarify the inherent functionality of OVs in photocatalysis at the surface molecular level using 2D BiOCl as the platform. Structure sensitivity of OVs on reactivity and selectivity of photocatalytic reactions is intensely discussed via confining OVs onto prototypical BiOCl surfaces of different structures. The critical understanding of OVs chemistry can help consolidate and advance the fundamental theories of photocatalysis, and also offer new perspectives and guidelines for the rational design of catalysts with satisfactory performance. [ABSTRACT FROM AUTHOR]

A low-cost zinc catalyst, prepared by a facile electrochemical strategy, produces CO with up to 93% Faraday efficiency in aqueous NaCl solution. The catalytic activity of the Zn catalyst is demonstrated to be dependent on both the morphology of the catalyst and the catholyte anions. [ABSTRACT FROM AUTHOR]