Layered Quasi-Nevskite Metastable-Phase Cobalt Oxide Accelerates Alkaline Oxygen Evolution Reaction Kinetics
Zhenglong Fan, Qintao Sun, Hao Yang, Wenxiang Zhu, Fan Liao, Qi Shao, Tianyang Zhang, Hui Huang, Tao Cheng, Yang Liu, Mingwang Shao, Minhua Shao, Zhenhui Kang
Abstract
Clarifying the structure–reactivity relationship of non-noble-metal electrocatalysts is one of the decisive factors for the practical application of water electrolysis. In this field, the anodic oxygen evolution reaction (OER) with a sluggish kinetic process has become a huge challenge for large-scale production of high-purity hydrogen. Here we synthesize a layered quasi-nevskite metastable-phase cobalt oxide (LQNMP-Co 2 O 3 ) nanosheet via a simple molten alkali synthesis strategy. The unit-cell parameters of LQNMP-Co 2 O 3 are determined to be a = b = 2.81 Å and c = 6.89 Å with a space group of P 3̅ m 1 (No. 164). The electrochemical results show that the LQNMP-Co 2 O 3 electrocatalyst enables delivering an ultralow overpotential of 266 mV at a current density of 10 mA cm geo –2 with excellent durability. The operando XANES and EXAFS analyses clearly reveal the origin of the OER activity and the electrochemical stability of the LQNMP-Co 2 O 3 electrocatalyst. Density functional theory (DFT) simulations show that the energy barrier of the rate-determining step (RDS) (from *O to *OOH) is significantly reduced on the LQNMP-Co 2 O 3 electrocatalyst by comparing with simulated monolayered CoO 2 (M-CoO 2 ).