In Situ Reconstructed Cu/Cu2+1O/ZnO Inverse Opals Accelerate Electrocatalytic Nitrate Reduction Kinetics for High Power Zn-NO3 - Battery.

Abstract

The electroreduction of NO3 - to NH3 (NO3RR) using renewable energy presents a promising strategy to mitigate environmental pollution and produce high-value chemicals. However, the practical application of NO3RR is hindered by limited active sites and sluggish reaction kinetics, stemming from the complex eight-electron process. Herein, a novel Cu/Cu2+1O/ZnO-2.5 inverse opals (CCZ-IOs-2.5) catalyst featuring a 3D porous network is designed, which provides abundant active sites and an optimized electronic structure to accelerate the NO3RR kinetics for efficient NH3 production. Experimental and theoretical calculations reveal that the introduction of ZnO facilitates electron transfer to Cu active sites, increasing charge density and lowering the reaction energy barrier of the rate-determining step (*NO to *NOH). As a result, CCZ-IOs-2.5 exhibits a notable enhancement in NH3 yield (from 0.255 to 0.313 mmol h-1 cm-2) and Faradaic efficiency (from 85.7% to 95.5%) compared to the Cu/Cu2+1O catalyst. Thanks to its excellent NO3RR activity, the Zn-NO3 - battery with the CCZ-IOs-2.5 cathode achieves a max power density of 11.93 mW cm-2. This study adopts a multi-dimensional strategy encompassing morphology regulation, electronic structure optimization, and surface/interface engineering, offering new insights into efficient electrocatalyst development and realizing integrated NH3 synthesis and energy output in a Zn-NO3 - battery.