In Situ Electrochemically Formed Ag/NiOOH/Ni<sub>3</sub>S<sub>2</sub> Heterostructure Electrocatalysts with Exceptional Performance toward Oxygen Evolution Reaction
Fangqing Wang, Yangyang Zhang, Jingqian Zhang, Wenhao Yuan, Ying Li, Jing Mao, Caichi Liu, Cong Chen, Hui Liu, Shijian Zheng
Abstract
Developing ultrahigh-activity and ultralong-durability electrocatalysts for oxygen evolution reaction (OER) in alkaline media is of great significance for large-scale alkaline water splitting. Herein, we report a self-supported heterostructure electrocatalyst composed of Ni3S2 nanosheet arrays decorated with Ag nanoparticles grown on nickel foam (Ag/Ni3S2/NF). Specifically, the insightful studies reveal that the amorphous NiOOH in situ formed on the surface of heterostructure electrocatalyst during OER (NiOOH@Ag/Ni3S2/NF) is regarded as the real active species. This self-constructed electrode only needs low overpotentials of 183, 195, and 263 mV at the current density of 10, 20, and 100 mA cm–2, respectively, as well as a low Tafel slope of 37 mV dec–1 in 1 M KOH, and is maintained for 500 h almost without any degradation at a high current density of 100 mA cm–2. Density functional theory (DFT) calculations reveal that the synergistic effects among multiple components can effectively boost the intrinsic OER activity via increasing conductivity and optimizing binding energy of oxygen-contained intermediates, and the enhanced Ni–O bonding accounts for the superior durability. This work provides deep insight into the key role of Ag on boosting both the catalytic activity and the stability of nickel sulfides toward OER.