MnO x H y -modified CoMoP/NF nanosheet arrays as hydrogen evolution reaction and oxygen evolution reaction bifunctional catalysts under alkaline conditions.

It is widely acknowledged that interface engineering strategies can significantly enhance the activity of catalysts. In this study, we developed a CoMoP nanoarray directly grown in situ on a nickel foam (NF) substrate, with the interface structure formed through the electrodeposition of MnO x H y . The resulting heterostructure MnO x H y /CoMoP/NF exhibited remarkable hydrogen evolution reaction (HER) activity, achieving overpotentials as low as 61 and 138 mV at 10 and 100 mA cm -2 , respectively. Moreover, MnO x H y /CoMoP/NF demonstrated efficient oxygen evolution reaction (OER) activity with an overpotential of 330 mV at 100 mA cm -2 . Remarkably, MnO x H y /CoMoP/NF maintained its catalytic properties and structural integrity even after working continuously for 20 h facilitating the HER at 10 mA cm -2 and the OER at 100 mA cm -2 . The Tafel slopes of the HER and OER were determined to be as small as 14 and 55 mV dec -1 , respectively, confirming that the coupled interface conferred fast reaction kinetics on the catalyst. When applied in overall water splitting, MnO x H y /CoMoP/NF delivered a voltage of 1.91 V at 100 mA cm -2 with excellent stability. This study demonstrated the feasibility of utilizing a simple electrodeposition technique to fabricate a heterogeneous structure with bifunctional catalytic activity, establishing a solid foundation for diverse industrial applications.