Spherical cluster heterojunction engineering of NiFeP/g-C₃N₄ for efficient oxygen evolution reaction in alkaline...

The construction of heterojunctions can reduce the energy barrier for the oxygen evolution reaction (OER), which is crucial for the design of efficient electrocatalysts. A novel OER electrocatalyst, composed of g-C₃N₄-supported NiFeP spherical nanoclusters, was successfully synthesized using a simple hydrothermal method and a gas-phase precipitation method. Benefiting from its unique spherical nanocluster structure and strong electronic interactions among Ni, Fe, and P, the catalyst exhibited outstanding performance under alkaline conditions, with an overpotential of only 232 mV at a current density of 10 mA cm^-2 and a Tafel slope of 103 mV dec^-1. Additionally, the electrical resistance of NiFeP/g-C₃N₄ (R_ct = 5.1 Ω) was much lower than that of NiFeP (R_ct = 10.8 Ω) and layered g-C₃N₄ (R_ct = 44.8 Ω). The formation of a Schottky barrier heterojunction efficiently reduced electron transfer impedance during the OER process, accelerating the electron transfer from g-C₃N₄ to NiFeP, enhancing the carrier concentration, and thereby improving the OER activity. Moreover, The robust g-C₃N₄ chain-mail protects NiFeP from adverse reaction environments, maintaining a balance between catalytic activity and stability. Furthermore, ab initio molecular dynamics (AIMD) and density functional theory (DFT) were conducted to explore the thermal stability and internal electron transfer behavior of the cluster heterojunction structure. This study offers a broader design strategy for the development of transition metal phosphide (TMPs) materials in the oxygen evolution reaction.