Enabling High Performance in a Positive Potential of Nitrate‐to‐Ammonia Electrocatalysis Over Mesoporous Core@Shell Cu<sub>2</sub>O/Cu@PdCu Nanozyme
Lizhi Sun, Xiaowen Min, Jingru Wang, Yuyang Yang, Shu Han, Dongping Fan, Yuqian Jing, Dongdong Xu, Wei Wang, Ben Liu
Abstract
Abstract Electrocatalytic tandem nitrate reduction to ammonia (NO 3 − ‐to‐NH 3 ) offers a promising pathway for energy and environmental sustainability. Although considerable efforts have been presented to modulate the reaction pathways for enhanced NO 3 − ‐to‐NH 3 electrocatalysis, these advances often require relatively high overpotentials to balance yield rate and selectivity of NH 3 , resulting in a remarkable energy inefficiency. Inspired by enzyme catalysis in nature, herein a tandem enzyme‐like electrocatalyst is designed consisting of a core of Cu 2 O/Cu heterojunction surrounded by mesoporous PdCu shell (Cu 2 O/Cu@mesoPdCu) that accelerated NO 3 − ‐to‐NH 3 electrocatalysis in positive potentials. Impressively, Cu 2 O/Cu@mesoPdCu nanozymes hold superior performance for robust NH 3 electrosynthesis in a fairly positive potential of 0.10 V (versus reversible hydrogen electrode), having Faraday efficiency of 96.2%, yield rate of 13.3 mg h −1 mg −1 , and half‐cell energy efficiency of 46.0%. Kinetic studies, in situ spectra and density functional theory calculations revealed that Cu 2 O/Cu core preferentially adsorbed NO 3 − and further reduced to *NO 2 , while active hydrogen radicals enriched on PdCu shell promoted multistep hydrodeoxygenation of *NO 2 to NH 3 within “semi‐closed” mesoporous microenvironment, both of which synergistically enabled tandem electrocatalysis in positive potentials. Moreover, this enzyme‐like electrocatalyst disclosed better NO 3 − ‐to‐NH 3 performance in a more energy‐efficient manner when coupling with more thermodynamically favorable ethanol oxidation reaction.