Highly Accessible Electrocatalyst with <i>I</i><i>n Situ</i> Formed Copper-Cluster Active Sites for Enhanced Nitrate-to-Ammonia Conversion
Zhen Shen, Fengfei Xu, Xueyi Cheng, Jietao Jiang, Changkai Zhou, Yu Zeng, Xizhang Wang, Lijun Yang, Qiang Wu, Zheng Hu
Abstract
Ammonia synthesis via nitrate electroreduction is more attractive and sustainable than the energy-extensive Haber–Bosch process and intrinsically sluggish nitrogen electroreduction. Herein, we have designed a single-site Cu catalyst on hierarchical nitrogen-doped carbon nanocage support (Cu 1 /hNCNC) for nitrate electroreduction, which achieves an ultrahigh ammonia yield rate (YR NH3 ) of 99.4 mol h –1 g Cu –1 (2.30 mol h –1 g cat. –1 ) with ammonia Faradaic efficiency (FE NH3 ) of 99.3%, far beyond the most reported single-site catalysts on carbon-based supports. The combined operando characterization and theoretical studies indicate that the in situ formed Cu-cluster active sites are responsible for the high YR NH3 and FE NH3 due to the enhanced NO 3 – adsorption and subsequent protonation on the unique Cu 3 –N 4 moieties, and meanwhile, the hierarchical hNCNC support facilitates the mass/charge transfer kinetics, thus promoting the high expression of intrinsic activity. The demonstration of plasma N 2 oxidization and nitrate electroreduction cascade reaction manifests the great potential of the Cu 1 /hNCNC electrocatalyst in sustainable NH 3 synthesis. These findings offer valuable insights into the design of effective catalysts for electrosynthetic reactions.