Activating lattice oxygen in layered lithium oxides through cation vacancies for enhanced urea electrolysis

Wenkai Han, Jinxin Wei, Kang Xiao, Ting Ouyang,  Xinwen Peng, Shenlong Zhao*, Zhaoqing Liu*
Angewandte Chemie International Edition, 134(31), e202206050, (2022)
DOI:https://doi.org/10.1002/ange.202206050

Abstract

Despite the fact that high-valent nickel-based oxides exhibit promising catalytic activity for the urea oxidation reaction (UOR), the fundamental questions concerning the origin of the high performance and the structure–activity correlations remain to be elucidated. Here, we unveil the underlying enhanced mechanism of UOR by employing a series of prepared cation-vacancy controllable LiNiO2 (LNO) model catalysts. Impressively, the optimized layered LNO-2 exhibits an extremely low overpotential at 10 mA cm−2 along with excellent stability after the 160 h test. Operando characterisations combined with the theoretical analysis reveal the activated lattice oxygen in layered LiNiO2 with moderate cation vacancies triggers charge disproportion of the Ni site to form Ni4+ species, facilitating deprotonation in a lattice oxygen involved catalytic process.