In situ coupled MoO3 with CoP/rGO to construct three-dimensional self-supported catalyst for highly efficient alkaline hydrogen evolution reaction

•A multi-component self-supporting MoO3@CoP@rGO composite was successfully synthesized on porous nickel foam.•The dense and uniform MoO3@CoP@rGO on the nickel foam produced synergistic effect and improved its HER-performance.•MoO3@CoP @rGO has very low initial overpotential of only 83 mV and Tafel slope of only 58.5 mV/dec.•The DFT calculation provides sufficient theoretical support for this experiment.