Interface and M 3+ /M 2+ Valence Dual‐Engineering on Nickel Cobalt Sulfoselenide/Black Phosphorus Heterostructure for Efficient Water Splitting Electrocatalysis

The catalyst innovation that aims at noble‐metal‐free substitutes is one key aspect for future sustainable hydrogen energy deployment. In this paper, a nickel cobalt sulfoselenide/black phosphorus heterostructure (NiCoSe|S/BP) was fabricated to realize the highly active and durable water electrolysis through interface and valence dual‐engineering. The NiCoSe|S/BP nanostructure was constructed by in‐situ growing NiCo hydroxide nanosheet arrays on few‐layer BP and subsequently one‐step sulfoselenization by SeS 2 . Besides the conductive merit of BP substrate, holes in p‐type BP are capable of oxidizing the Co 2+ to high‐valence and electron‐accepting Co 3+ , benefiting the oxygen evolution reaction (OER). Meanwhile, Ni 3+ /Ni 2+ ratio in the heterostructure is reduced to maintain the electrical neutrality, which corresponds to the increased electron‐donating character for boosting hydrogen evolution reaction (HER). As for HER and OER, the heterostructured NiCoSe|S/BP electrocatalyst exhibits small overpotentials of 172 and 285 mV at 10 mA cm −2 ( η 10 ) in alkaline media, respectively. And overall water splitting has been achieved at a low cell potential of 1.67 V at η 10 with high stability. Molecular sensing and density functional theory (DFT) calculations are further proposed for understanding the rate‐determine steps and enhanced catalytic mechanism. The investigation presents a deep‐seated perception for the electrocatalytic performance enhancement of BP‐based heterostructure.