Two-dimensional CoS/Co-MOF Composite Electrocatalyst for Efficient Oxygen Evolution Reaction
Manqi Liu, Baiming Liang, Yu Liang, Ying Peng, Yuxuan Lin, Zhikuan Wang, Yu Wang, Zemei Tan, Yulu Yang, Hongxia Xi, Jingjing Li, Chongxiong Duan
Abstract
The oxygen evolution reaction (OER) is the key anodic reaction in water electrolysis for hydrogen production. Herein, a novel two-dimensional (2D) CoS/Co-MOF composite electrocatalyst was successfully synthesized using a post-synthesis method. The as-synthesized 2D CoS/Co-MOF composite employed as an OER electrocatalyst exhibits an exceptionally low overpotential of 327 mV at a current density of 100 mA cm<sup>−2</sup>, considerably outperforming most reported transition metal sulfide catalysts (e.g., NiS/MOFs: 368 mV, Co<sub>9</sub>S<sub>8</sub>@MoS<sub>2</sub>/Co-MOFs: 350 mV). Furthermore, the resulting CoS/Co-MOF OER electrocatalyst demonstrates exceptional stability, maintaining stable catalytic activity after 20 h of constant-current operation and exhibiting minimal degradation after 30 days of air exposure. In addition, a systematic investigation of key parameters (e.g., the thioacetamide (TAA) content and reaction temperature) was conducted to identify the optimal process conditions. Moreover, the catalytic mechanism of CoS/Co-MOF electrocatalyst was further elucidated based on density functional theory (DFT) calculations. These results reveal that the introduction of CoS can modulate the d-band centre of the CoS/Co-MOF, thereby optimizing adsorption free energy and reducing the overpotential. This synergy between the structure and optimized synthesis parameters advances the sustainable development of high-performance OER electrocatalysts. This work offers a feasible method for designing efficient and durable electrocatalysts that can facilitate large-scale applications of water electrolysis for hydrogen production.