Advanced design of metal single-atom (Pt, Mn, Fe or Cu) loaded S-Ni(OH)2 nanosheets array catalysts to achieve high-performance overall water splitting

Designing catalysts at atomic level fine-tune the electronic structure of surface-active site for efficient water splitting, is a highly desirable approach but also poses significant challenges. This study focuses on the synthesis of a series of electronically tunable metal single-atom (M−SAs) catalysts: M 9 @S-Ni(OH) 2 (M=Pt, Mn, Fe or Cu). Experimental results reveal that introduction of trace S-heteroatoms and metal atoms into Ni(OH) 2 lattice can effectively modulate the electronic structure of M 9 @S-Ni(OH) 2 through modulation of p-d and d-d orbital hybridization, resulting in exceptional performance in water electrolysis. Among M 9 @S-Ni(OH) 2 , Pt 9 @S-Ni(OH) 2 and Fe 9 @S-Ni(OH) 2 exhibit excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance, respectively, the overpotential requiring only 7 mV and 269 mV, respectively, at current density of 10 mA cm −2 . (−) Pt 9 @S-Ni(OH) 2 ||Fe 9 @S-Ni(OH) 2 (+) presents a high current density of 531.07 mA cm −2 at cell-voltage of 1.80 V in overall-water splitting (OWS), which is 14.07 times higher than that of the commercial (−) Pt/C||IrO 2 (+) (37.86 mA cm −2 ) system. This work achieves the development of cost-effective and stable electrocatalysts, offering a solution for large-scale and sustainable water-hydrogen conversion.