Electrochemical nitrate reduction as affected by the crystal morphology and facet of copper nanoparticles supported on nickel foam electrodes (Cu/Ni)

By Yu-Jen Shih, Zhixing Wu, Y. Huang, C. Huang. 2020

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Abstract Cu/Ni composite electrodes were prepared and studied for the electrochemical reduction of nitrate in aqueous solutions. Electrodeless plating technique, with tartrate as chelatant and formaldehyde as reducing agent, enabled the in-situ incorporation of Cu nanoparticles into the open-pore structured Ni foam to form Cu-Ni composite electrodes. X-ray diffractometer (XRD) and scanning electron microscopy (SEM) revealed that the crystal facet and grain morphology of Cu nanoparticles was closely controlled by the plating time and played a significant role in nitrate reduction and nitrogen selectivity. Cyclic voltammetry provided information on the electron transfer between surface nitrogen species and Cu/Ni electrodes. Electrochemical nitrate reduction was initiated at the onset potential of Cu(0)/Cu(I) redox reaction over a potential window of −0.6 V to −1.2 V. The preferential Cu{1 1 1} facet orientation improved the electron transfer process. Batch kinetics studies at constant current and potential showed that specific adsorption of nitrate and nitrite on the Cu{1 1 1} facet was critical to efficient electrochemical nitrate reduction. Moreover, the conversion of nitrogenous byproduct was potential-dependent. Results showed that N2 selectivity was high (55.6%) at low overpotential (i.e., ⩾ −0.6 V vs. Hg/HgO. At high overpotential (i.e,

Subfields: Catalysis, Organic Chemistry, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/d443faaba1fe4bb84a7880db27da2bd9a1629fcc