Hexagonal Cobalt Nanosheets for High-Performance Electrocatalytic NO Reduction to NH<sub>3</sub>
Dongdong Wang, Zhiwen Chen, Kaizhi Gu, Chen Chen, Yingying Liu, Xiaoxiao Wei, Chandra Veer Singh, Shuangyin Wang
Abstract
Electrocatalytic nitric oxide (NO) reduction not only provides an extremely promising strategy for ambient NH 3 generation but also alleviates the artificially disrupted N-cycle balance. However, exploring efficient electrocatalysts to enhance the NO electroreduction performance remains a significant challenge. Herein, a hexagonal-close-packed Co nanosheet (hcp-Co) is prepared and exhibits a high NH 3 yield of 439.50 μmol cm –2 h –1 and a Faraday efficiency of 72.58%, outperforming the face-centered cubic phase of the Co nanosheet (fcc-Co) and most reported electrocatalysts. Through the combination of density functional theory calculations and NO temperature-programmed desorption experiments, the superior catalytic NO reduction reaction (NORR) activity on the hcp-Co can be attributed to the unique electron structures and proton shuttle effect. A proof-of-concept device of Zn–NO batteries using the hcp-Co as the cathode is assembled and shows a power density of 4.66 mW cm –2, which is superior to the reported performance in the literature so far.