A Branch-Leaf-Like Hierarchical Self-Supporting Electrode As A Highly Efficient Catalyst For Hydrogen Evolution

Inspired by the advanced branch-leaf hierarchical structure of natural trees, a composite catalyst with a branch-leaf-like hierarchical structure was reported for the first time. This catalyst, which grows on Ni foam, consists of NiCo alloy nanobranches and MoO3-x nanoleaves embedded with MoNi4 nanoparticles. The NiCo alloy nanobranches as an electron transfer highway can effectively improve the conductivity of the catalyst. The MoO3-x nanoleaves not only provide HER active sites, i.e. water dissociation center (MoO3-x) and H-ads adsorption/desorption center (MoNi4), but also increase the specific surface area, expose more active sites and promote the mass transfer of the catalyst. Benefiting from the branch-leaf hierarchical structure and synergistic effect of the components, this composite catalyst exhibits high HER activity which is comparable to that of 20% Pt/C in the alkaline solution. It requires a very low overpotential (33 mV) to reach 10 mA cm(-2), and the Tafel slope is only 34 mV dec(-1). The HER activity of the catalyst in simulated seawater is better than that of 20% Pt/C. This work shows a meaningful reference for the design and synthesis of a high efficiency non-noble metal HER catalyst used in alkaline water electrolysis.