Strengthened Synergistic Effect of Metallic M_x P_y (M = Co, Ni, and Cu) and Carbon Layer via Peapod-Like Architecture for Both Hydrogen and Oxygen Evolution Reactions

The smooth electric transmission is crucial for the high-efficient electrocatalysis. Herein, a series of peapod-like metallic M_x P_y /C (M = Co, Ni, and Cu) composites is developed as bifunctional catalysts toward hydrogen and oxygen evolution reactions. For the first time, the metallic property of Cu₃ P is confirmed through the theoretical calculation. The in-depth composition, structural and catalytic mechanism analysis of M_x P_y /C discloses that the comparable activity and considerable durability of these catalysts mainly result from the strengthened synergistic effect between metallic M_x P_y and carbon layer based on the unique peapod-like architecture. Especially, the atomic contact between M_x P_y and carbon not only provides an open channel for electronic transmission but also ensures the integrity of peapod-like structure. Furthermore, the high electric conductivity of the inner metallic M_x P_y and the outer carbon layer endows the M_x P_y /C catalyst with rapid charge migration during the electrocatalytic pathway. These findings shed light on the origin of high catalytic activity of M_x P_y /C and open a path for purposefully rationally synthesizing superior electrocatalysts.