Effective construction of 3D Rh/Rh2P flake-like assembled heterostructures for efficient hydrogen evolution

•3D Rh/Rh2P nano-flake assemblies have large active area and structure stability.•The P cooperation significantly facilitates water dissociation and hydrogen release.•The unique assembly has abundant interfaces with optimized electronic structures.•The catalyst exhibit improved performances for hydrogen evolution reaction. [Display omitted] Nowadays, the application of electrochemical water splitting is seriously hindered by sluggish hydrogen evolution reaction (HER) in alkaline electrolyte. To overcome this issue, three-dimensional (3D) Rh/Rh2P nano-flake assemblies (Rh/Rh2P-NFAs) were successfully synthesized via partial phosphating in this study. The efficient corporation of P effectively facilitated the adsorption and desorption processes of protons and thus created abundant Rh/Rh2P heterointerfaces in the Rh/Rh2P-NFAs. By virtues of the large active area, fine-modulated electronic structures and improved electrical conductivity, the Rh/Rh2P-NFAs only require the overpotentials of 19.5 mV and 13.4 mV to achieve 10 mA cm−2 in 1.0 M KOH and 0.5 M H2SO4 solutions, respectively, outperforming most of the previous electrocatalysts. Also, the Rh/Rh2P-NFAs also exhibit amazing electrocatalytic stability during the long-term testing, making it a promising candidate for the HER in both alkaline and acidic media.