Electron transfer at the heterojunction interface of CoP/MoS for efficient electrocatalytic hydrogen evolution reaction.

Modulating the electronic states of electrocatalysts is critical for achieving efficient hydrogen evolution reaction (HER). However, how to develop electrocatalysts with superior electronic states is an urgent challenge that must be addressed. Herein, we prepared the CoP/MoS heterojunction with a microsphere morphology consisting of thin nanosheets using a facile two-step method. The catalyst's ultrathin nanosheet structure not only provides an extensive surface area for exposing active sites, but it also enables ion transport and bubble release. Electron transfer occurs between CoP and MoS, optimizing the heterojunction's charge distribution and enhancing the intermediates' adsorption capabilities. As a result, the CoP/MoS heterojunction exhibits outstanding electrocatalytic hydrogen evolution activity with an overpotential of only 88 mV at a current density of 10 mA cm, which exceeds both the sulfide heterojunction CoS/MoS and the phosphide heterojunction CoP/CoMoP. The experimental results and DFT calculation results show that the former has stronger synergistic effects and higher HER activity. This work sheds light on the exploration of efficient heterojunction electrocatalysts with excellent electronic structures.