Electrocatalytic reduction of nitrate to dinitrogen by Cu2O/CF electrode
GUO Feng1,2, XIE Chen-xin2, HAN En-shan1, ZHANG Cheng-lei2, ZHAO Hui2, TENG Hou-kai2
1. School of Chemical Engineering, Hebei University of Technology, Tianjin 300401, China; 2. CNOOC Tianjin Chemical Industry Research and Design Institute, Tianjin 300131, China
Abstract：During the whole electrolysis process, the electrocatalytic activity of cathode materials is affected by the multi-electron kinetic reaction. Presently, copper-based materials have received much attention as one of the most significant electrochemical nitrate reduction reaction (NITRR) electrocatalysts. However, there are still no reports of effective solutions to the problems of activity limitation and selectivity. In this work, we compared the NITRR performance of s-Cu2O/CF and e-Cu2O/CF catalysts prepared on copper foam (CF) by in situ growth and electrodeposition, respectively. An extremely high NO3- removal rate of 92.1% and N2selectivity of 81.1% were attained by the s-Cu2O/CF catalyst in the electrolyte containing 0.05mol/L Cl- and 100mg/L NO3--N. Cyclic voltammetry and linear sweep voltammetry showed that the NITRR process was achieved by electron transfer between nitrate (NO3-) and Cu0derived from CF. In situ grown s-Cu2O/CF, as a bifunctional catalyst for electronic media or bridge, promotes not only NO3- reduction but also the production of reduced hydrogen (H*), which further enhances the conversion of NO2- to NH4+ or N2. After eight cycles of experiments, s-Cu2O/CF still maintained excellent electrocatalytic activity, which further demonstrates its great application potential in the NITRR. Furthermore, a two-step treatment strategy of Ir-Ru/Ti anodic pre-oxidation and s-Cu2O/CF cathodic post-reduction was adopted to remove 93.6% of chemical oxygen demand (COD) and 75.2% of total nitrogen (TN) from the actual wastewater.
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