Interface Engineering of Partially Phosphidated Co@Co-P@NPCNTs for Highly Enhanced Electrochemical Overall Water Splitting

Interface engineering is promising but still challenging for developing highly efficient and stable non-noble-metal-based electrocatalysts for water splitting. Herein, partially phosphidated core@shell Co@Co-P nanoparticles encapsulated in bamboo-like N, P co-doped carbon nanotubes (denoted as Part-Ph Co@Co-P@NPCNTs) are prepared through a pyrolysis-oxidation-phosphidation strategy. In this structure, each Co nanoparticle is covered with a thin Co-P layer to form a special core@shell heterojunction interface, and the core@shell structure is further encapsulated by N, P co-doped CNTs that not only protect the Co from corrosion but also guarantee an effective and fast electron transfer on cobalt phosphide. As a bifunctional catalyst for both the hydrogen evolution reaction and oxygen evolution reaction, it exhibits an excellent activity for overall water splitting, and enables long-term operation without significant degradation. Density functional theory calculations demonstrate that the interface of the Co/Co2P heterojunction could lower the values of Delta G(H)* (hydrogen adsorption) and Delta G(B)(water dissociation), which are negatively correlated to thej(10), because of the electronic structures of up-shiftedd-band center. This study not only presents an efficient and stable electrocatalyst for overall water splitting but also provides a special route for the interface engineering of heterostructures.