Ultrafine Pt Nanoparticle‐Decorated Pyrite‐Type CoS2 Nanosheet Arrays Coated on Carbon Cloth as a Bifunctional Electrode for Overall Water Splitting

Abstract To improve the utilization efficiency of precious metals, metal‐supported materials provide a direction for fabricating highly active and stable heterogeneous catalysts. Herein, carbon cloth (CC)‐supported Earth‐abundant CoS 2 nanosheet arrays (CoS 2 /CC) are presented as ideal substrates for ultrafine Pt deposition (Pt‐CoS 2 /CC) to achieve remarkable performance toward the hydrogen and oxygen evolution reactions (HER/OER) in alkaline solutions. Notably, the Pt‐CoS 2 /CC hybrid delivers an overpotential of 24 mV at 10 mA cm −2 and a mass activity of 3.89 A Pt mg −1 , which is 4.7 times higher than that of commercial Pt/C, at an overpotential of 130 mV for catalyzing the HER. An alkali‐electrolyzer using Pt‐CoS 2 /CC as a bifunctional electrode enables a water‐splitting current density of 10 mA cm −2 at a low voltage of 1.55 V and can sustain for more than 20 h, which is superior to that of the state‐of‐the‐art Pt/C+RuO 2 catalyst. Further experimental and theoretical simulation studies demonstrate that strong electronic interaction between Pt and CoS 2 synergistically optimize hydrogen adsorption/desorption behaviors and facilitate the in situ generation of OER active species, enhancing the overall water‐splitting performance. This work highlights the regulation of interfacial and electronic synergy in pursuit of highly efficient and durable supported catalysts for hydrogen and oxygen electrocatalytic applications.