La-triggered synthesis of oxygen vacancy-modified cobalt oxide nanosheets for highly efficient oxygen evolution in alkaline media

Oxygen vacancies (O-vac) can improve electrocatalytic activities in the oxygen evolution reaction (OER) process but remain a great challenge. Herein, we report a facile two-step approach to synthesizing La-oped CoOx nanosheets (NSs) with abundant oxygen vacancies by a La-triggered effect. Profiting from enriched O-vac and fast charge transfer, La-doped CoOx NSs deliver a remarkably high OER activity with a low overpotential of 353 mV at 10.0 mA m(-2) and a Tafel slope of 78.2 MV dec(-1), surpassing those of initial CoOx, IrO2, and most reported non-noble metal based electrocatalysts. In addition, they also exhibit superior durability with only slight degradation after continuous operation of 35 h in a 0.1 M KOH solution. Undoubtedly, the results inspire the use of La into the oxygen vacancies to explore highly active catalysts for various applications. (C) 2019 Elsevier B.V. All rights reserved.