Ni Single Atoms and Ni Phosphate Clusters Synergistically Triggered Surface‐Functionalized MoS<sub>2</sub> Nanosheets for High‐performance Freshwater and Seawater Electrolysis
Min Sung Kim, Duy Thanh Tran, Thanh Hai Nguyen, Van An Dinh, Nam Hoon Kim, Joong Hee Lee
Abstract
Two‐dimensional metal dichalcogenides have been evidenced as potential electrocatalysts for hydrogen evolution reaction (HER); however, their application is limited by a poor oxygen evolution reaction (OER) activity due to insufficient number/types of multi‐integrated active sites. In this study, we report a novel bifunctional catalyst developed by simultaneous engineering of single nickel atoms (Ni SA ) and nickel phosphate clusters (Ni Pi ) to synergistically trigger surface‐functionalized MoS 2 nanosheets (NSs) resulting in high reactivities for both HER and OER. The Ni SA ‐Ni Pi /MoS 2 NSs material exhibits a fairly Pt‐like HER behavior with an overpotential of 94.0 mV and a small OER overpotential of 314.0 mV to reach 10 mA cm −2 in freshwater containing 1.0 M KOH. Experimental results of the catalyst are well supported by theoretical study, which reveals the significant modulation of electronic structure and enrichment of electroactive site number/types with their reasonably adjusted free adsorption energy. For evaluating practicability, the Ni SA ‐Ni Pi /MoS 2 NSs‐based electrolyzer delivers effective operation voltage of 1.62, 1.52, and 1.66 V at 10 mA cm −2 and superior long‐term stability as compared to Pt/C//RuO 2 system in freshwater, mimic seawater, and natural seawater, respectively. The present study indicates that the catalyst is a promising candidate for the practical production of green hydrogen via water electrolysis.