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||IrO2 (+) (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.