Open N-doped carbon coated porous molybdenum phosphide nanorods for synergistic catalytic hydrogen evolution reaction

Molybdenum phosphide is a potential hydrogen evolution reaction (HER) catalyst. However, traditional high-temperature phosphating preparation methods are prone to damage of material morphology and agglomeration. Using the carbon skeleton to limit the size and morphology of MoP and to improve the conductivity of the material is an effective method to improve the performance of the catalyst. However, there is a lack of research on the effect of carbon skeleton and MoP composite structure on the catalytic mechanism of HER. We coated ZIF-8 on the surface of MoP nanorods, and obtained open N-doped carbon-coated porous MoP nanorods (N/C/MoP) through carbonization and phosphating. Studies have shown that the ZIF-8 coating effectively limits the size and morphology of the material and avoids agglomeration. Under alkaline conditions, N/C/MoP has a low overpotential of 169 mV for HER at 10 mA/cm2, which is 55 mV lower than MoP without a carbon layer. At the same time, its Tafel slope (51.3 mV/dec) is smaller than Pt/C (59.9 mV/dec), and it has good stability. Density functional theory (DFT) studies have shown that under alkaline conditions, there is a synergistic effect between the open N-doped carbon layer and the exposed MoP active surface, which reduces the activation energy of water and improves the catalytic performance of HER. It is worth noting that a tight coating will hinder the exposure of active sites and reduce catalytic activity.