Interface construction and porosity engineering to trigger efficient hydrogen evolution of two-dimensional porous molybdenum phosphide/dioxide heterojunction nanosheets in acidic and alkaline electrolytes

Construction of nanosized pore and heterointerface provides an efficient way to enhance the electrocatalytic activity of hydrogen evolution reaction (HER). However, the exploration to tailor these structures is still insufficient for two-dimensional (2D) catalysts. Herein, a facile phosphine (PH3) and hydrogen (H2) vapor-assisted phase engineering strategy is proposed to successfully achieve the controllable conversion of 2D MoO2 nanosheet precursor into 2D porous MoP/MoO2 heterojunction nanosheets for HER. The holey lamellar properties and plentiful interfaces between 2D MoP and MoO2 domains are intuitively confirmed by high-resolution transmission electron microscopy images. The porous MoP/MoO2 nanosheets exhibit outstanding HER activity with low overpotentials of 90 ± 1 and 79 ± 1 mV to drive a current density of 10 mA cm−2 in acidic and alkaline electrolytes, respectively. Density functional theory calculations reveal that both P and Mo sites located on the wall of the nanopores at the interface region optimize the hydrogen binding energy, thereby accelerating the HER kinetics.