Identifying the active site of Cu/Cu2O for electrocatalytic nitrate reduction reaction to ammonia
Identifying the active site of Cu/Cu2O for electrocatalytic nitrate reduction reaction to ammonia
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DOI：
10.1016/j.checat.2023.100850
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发表时间：
2023-12
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通讯作者：
Gabriel F. Costa;Manuel Winkler;Thiago Mariano;M. R. Pinto;Igor Messias;João B. Souza;I. Neckel;Maria F.C. Santos;Cláudio F Tormena;Nirala Singh;Raphael Nagao
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作者：
Gabriel F. Costa;Manuel Winkler;Thiago Mariano;M. R. Pinto;Igor Messias;João B. Souza;I. Neckel;Maria F.C. Santos;Cláudio F Tormena;Nirala Singh;Raphael Nagao
氧化铜衍生的电催化剂对硝酸氮还原反应（NO3RR）产生氨具有较高的活性和选择性。然而，它们增强nh3形成的原因尚不清楚。我们测量了不同预还原Cu/Cu2O催化剂的NO3RR活性，并将其与金属Cu进行比较，以确定硫酸钠电解质中NO3RR对氨的活性位点。使用无缓冲电解液时，由于pH值在NO3RR过程中升高，催化剂的动力学性能与碱性催化剂（pH值为12）相似。与pH值为5.8时缓冲的电解质相比，pH值越高，NO3RR制nh3的催化剂性能越好。利用原位光谱，我们检测到与标准氢电极（SHE）相比，Cu2O在−0.6 V时减少，并且检测到羟胺（一种NO3RR中间体）在−0.7 V至−1.0 V时减少。我们提出氧空位促进NO3RR在−0.6 ~−0.77 V / SHE范围内生成氨，而铜在−1.1 V / SHE范围内是活性位点。
Copper oxide-derived electrocatalysts are reported to have high activity and selectivity for nitrate electrochemical reduction reaction (NO3RR) to ammonia. However, the cause underlying their enhanced NH3formation remains unclear. We measure the NO3RR activity of differently pre-reduced Cu/Cu2O catalysts and compare them to metallic Cu to identify the active site for NO3RR to ammonia in sodium sulfate electrolyte. Using unbuffered electrolyte, catalyst kinetic performance is similar to the alkaline one (pH 12) due to pH increases during NO3RR. Higher pH values improve catalyst performance for NO3RR to NH3compared to electrolyte buffered at pH 5.8. Usingin situspectroscopies, we detect that Cu2O reduces at −0.6 V vs. standard hydrogen electrode (SHE) and detect hydroxylamine, a NO3RR intermediate, from −0.7 V to −1.0 V vs. SHE. We propose that oxygen vacancies promote NO3RR to ammonia from −0.6 to −0.77 V vs. SHE, while copper is the active site at −1.1 V vs. SHE.