Synthetic Self-Supporting Honeycomb MoNiP@(Ni,Cu,Fe)₃P Catalysts for Efficient Hydrogen Evolution

In this study, the composite addition effect of Fe and Mo on the microstructure evolution and hydrogen evolution performance of Ni–P metallic catalysts was investigated in details. After dealloying treatment, the bulk self-supporting MoNiP@(Ni,Cu,Fe)3P catalysts with a honeycomb structure were successfully synthesized through an in situ melt reaction. It was found that Mo elements mainly existed in the form of MoNiP precipitation plates, which were embedded in (Ni,Cu,Fe)3P skeletons resulting in the improvement of structure stability of dealloyed products during the electrocatalytic process. With the composite addition of 2 wt % Fe and 3.5 wt % Mo, it was found that the MoNiP@(Ni,Cu,Fe)3P–2 dealloyed sample possessed an optimum overpotential of 154 mV@10 mA cm–2 as well as a Tafel slope of 74.9 mV dec–1, which could still exhibit an excellent stability after 1000 CV cycles and 60 h durability tests in 1 M KOH aqueous solution. Based on the analyses of Cdl and ESCA values, it was revealed that the three-dimensional porous MoNiP@(Ni,Cu,Fe)3P metallic catalysts had an obvious improvement with the increase in the specific surface area and the exposure of active sites. Through XPS and FESEM analyses before and after dealloying, it was determined that the transport path of mass electrons of MoNiP@(Ni,Cu,Fe)3P catalysts has been remarkably promoted with Fe/Mo codoping, which could further improve the hydrogen evolution efficiency of water splitting.