Sulfur-vacancy engineering of CoS/TiCT-MXene catalyst for efficient oxygen evolution reaction.

Integrating conductive supports and modulating electronic structures are widely recognized as effective strategies for improving the catalytic performance of transition metal sulfides. This study demonstrates the simultaneous integration of CoS with two-dimensional TiCT-MXene and the introduction of sulfur vacancies (S) in CoS through a straightforward sintering process followed by plasma treatment, culminating in the formation of the CoS/TiCT composite. Characterization results demonstrate that the TiCT support significantly improves electrical conductivity and promotes the uniform dispersion of CoS nanoparticles. Experimental and theoretical analyses reveal that the introduction of S induces charge redistribution and optimizes the adsorption of reaction intermediates. The obtained CoS/TiCT electrode exhibits superior oxygen evolution reaction (OER) performance, achieving an overpotential of 286 mV at a current density of 10 mA cm and a Tafel slope of 76 mV dec, outperforming other counterparts and approaching the catalytic performance of commercial RuO catalyst. Furthermore, it demonstrates exceptional stability, with a potential shift of only 18 mV during a durability test exceeding 13 h. As an anodic catalyst for water splitting, the CoS/TiCT electrode achieves a low overpotential of 330 mV, highlighting its potential for practical water electrolysis applications. This study offers valuable insights into the design and development of advanced transition metal sulfide-based OER catalysts.