In Situ Construction of Cu <sup>1+</sup> /Cu <sup>0</sup> and Cu <sup>2+</sup> /Cu <sup>0</sup> Pairs of Cu‐Based Catalysts for Electrocatalytic Nitrate Reduction
Shanna An, Jiali Ren, Yanjun Xue, Jian Tian
Abstract
Abstract Electrocatalytic nitrate reduction reaction (NO 3 RR) as a sustainable nitrogen cycle regulation strategy provides a new pathway to achieve carbon neutrality goals. In this study, CuO, Cu 2 P 2 O 7 and Cu 3 (PO 4 ) 2 (CuPO) are synthesized as pre‐catalysts via a sol‐gel process for NO 3 RR, in which CuO exhibits excellent NH 3 yields of 8.16 mg h −1 mg cat −1 (FE = 95.72%, ‐0.95 V vs. RHE) compared to Cu 2 P 2 O 7 (7.33 mg h −1 mg cat −1 , 94.88%) and Cu 3 (PO 4 ) 2 (6.53 mg h −1 mg cat −1 , 92.04%). The combination of in situ Raman and XPS spectra reveal that the pre‐catalyst surface is reconfigured to form stable active sites of Cu 1+ /Cu 0 (CuO‐derived) and Cu 2+ /Cu 0 pairs (CuPO‐derived) during the NO 3 RR process. Tracking the evolution of intermediates using online differential electrochemical mass spectrometry (DEMS) spectra and in situ Fourier transform infrared spectroscopy (FT‐IR) spectra reveal that Cu 1+ /Cu 0 pairs possess rapid catalytic kinetics for the conversion of *NO 3 − to *NO 2 − . Density functional theory (DFT) calculations confirm that Cu 1+ /Cu 0 exhibits a lower potential‐determining step, and its exceptional *H generation and enrichment capabilities promote further hydrogenation reactions, thereby achieving excellent activity and selectivity in NH 3 production via NO 3 RR. This study reveals the distinct advantages of reconstructed active sites in Cu‐based catalysts during NO 3 RR, providing guidance for designing other advanced catalysts.