Chen Xinhong, Cheng Yumeng, Zhang Bo, Zhou Jia, He Sisi
State Key Laboratory of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen, China.
School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China.
Nat Commun. 2024 Jul 25;15(1):6278. doi: 10.1038/s41467-024-50670-w.
Electrocatalytic nitrate reduction to ammonia holds great promise for developing green technologies for electrochemical ammonia energy conversion and storage. Considering that real nitrate resources often exhibit low concentrations, it is challenging to achieve high activity in low-concentration nitrate solutions due to the competing reaction of the hydrogen evolution reaction, let alone considering the catalyst lifetime. Herein, we present a high nitrate reduction performance electrocatalyst based on a Co nanosheet structure with a gradient dispersion of Ru, which yields a high NH Faraday efficiency of over 93% at an industrially relevant NH current density of 1.0 A/cm in 2000 ppm NO electrolyte, while maintaining good stability for 720 h under -300 mA/cm. The electrocatalyst maintains high activity even in 62 ppm NO electrolyte. Electrochemical studies, density functional theory, electrochemical in situ Raman, and Fourier-transformed infrared spectroscopy confirm that the gradient concentration design of the catalyst reduces the reaction energy barrier to improve its activity and suppresses the catalyst evolution caused by the expansion of the Co lattice to enhance its stability. The gradient-driven design in this work provides a direction for improving the performance of electrocatalytic nitrate reduction to ammonia.
电催化硝酸盐还原为氨对于开发用于电化学氨能量转换和存储的绿色技术具有巨大潜力。考虑到实际的硝酸盐资源通常浓度较低，由于析氢反应的竞争，在低浓度硝酸盐溶液中实现高活性具有挑战性，更不用说考虑催化剂的寿命了。在此，我们展示了一种基于具有Ru梯度分散的Co纳米片结构的高硝酸盐还原性能电催化剂，在2000 ppm NO电解液中，在1.0 A/cm²的工业相关NH₃电流密度下，其NH₃法拉第效率超过93%，同时在-300 mA/cm²下保持720小时的良好稳定性。即使在62 ppm NO电解液中，该电催化剂也能保持高活性。电化学研究、密度泛函理论、电化学原位拉曼光谱和傅里叶变换红外光谱证实，催化剂的梯度浓度设计降低了反应能垒以提高其活性，并抑制了由Co晶格膨胀引起的催化剂析氢以增强其稳定性。这项工作中的梯度驱动设计为提高电催化硝酸盐还原为氨的性能提供了一个方向。
