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

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 (Rct = 5.1 Ω) was much lower than that of NiFeP (Rct = 10.8 Ω) and layered g-C3N4 (Rct = 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.

First principles study on electronic properties and oxygen evolution mechanism of 2D bimetallic N-doped graphene.

Currently, the oxygen evolution reaction (OER) is constrained by complex four-electron transport, thus it is difficult to understand the catalytic mechanism. In this work, the electronic properties and catalytic performance of M1M2/NC (M = Mn, Fe, Co, Ni, Cu and Zn, random combination in pairs) is studied by density functional theory, the calculated results show that the overpotential of FeCu/NC is 0.88 V, which is used as the optimal catalyst to further study the OER reaction mechanism. Combined with the volcano map and the d-band center position, the low overpotential of FeCu/NC is because it has a more suitable position of d-band center -1.806 eV than other materials. Moreover, the calculation results show that the density of states (DOS) of iron-containing materials is stronger than that of other materials near the Fermi level, which can promote the catalytic reaction. In addition, O∗OH and O∗H, O∗H and O∗ linearly related theoretical equations are proposed, respectively. Furthermore, the analysis of the catalytic mechanism shows that the formation of the catalytic rate-determining step is affected by the movement of the d-band center, the distance of the transition state adsorption and the electric field.