MnOxHy-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 MnOxHy. The resulting heterostructure MnOxHy/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, MnOxHy/CoMoP/NF demonstrated efficient oxygen evolution reaction (OER) activity with an overpotential of 330 mV at 100 mA cm-2. Remarkably, MnOxHy/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, MnOxHy/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.

Self-supported CoMoO4/NiFe-LDH core-shell nanorods grown on nickel foam for enhanced electrocatalysis of oxygen evolution.

Developing high-performance catalysts is an effective strategy for speeding up the oxygen evolution reaction (OER) and increasing production efficiency. Here, a core-shell electrocatalyst consisting of CoMoO4 nanorods grown in situ on nickel foam substrate covered by nickel-iron layered double hydroxide (NiFe-LDH) via electrodeposition was demonstrated (CoMoO4/NiFe-LDH@NF). Experimental investigations revealed that self-supporting and binder-free electrodes ensured that the catalysts exposed an abundance of active sites, faster electron transfer, and excellent long-cycle stability. The NiFe-LDH shell with a crystalline-amorphous dual structure served as an accurate active material, lowering the energy barrier and contributing more catalytic sites for water oxidation. Furthermore, the core CoMoO4 nanorods not only effectively avoided the accumulation of NiFe-LDH to increase the electrochemically active area but also acted as a highway for electrons from the active site to the substrate to promote the OER kinetics. Specifically, CoMoO4/NiFe-LDH@NF exhibited lower overpotential (180 mV at 10 mA cm-2) and smaller Tafel slope (34 mV dec-1) than pure CoMoO4@NF and NiFe-LDH@NF, revealing its excellent catalytic performance and fast intrinsic reaction kinetics. In addition, CoMoO4/NiFe-LDH@NF exhibited long-term stability of more than 20 h at 50 mA cm-2, further demonstrating its potential for practical applications. These findings pointed to a potential option for building innovative OER catalysts.