Organophosphine ligand derived sandwich-structural electrocatalyst for oxygen evolution reaction

Abstract

The synchronous construction of metal phosphate and phosphorus-doped carbon structures is of great significance to innovate the design, synthesis, and application of catalysts, as these phosphorus-containing composite materials have shown a remarkable contribution to electrocatalysts. However, their preparation procedure generally involves using large amounts of excess phosphorus sources for phosphorization, which inevitably release poisonous PH3 or dangerous phosphorus vapor. Here, a strategy for in-situ formation of FePO4 embedded in P-doped carbon 2D nano film (FePO4/PdC) is developed using a highly integrated precursor, which is a small molecular organophosphine ligand, 1,1′bis (diphenylphosphine) ferrocene (DPPF). The multi-source precursor DPPF that contains Fe, P, and C is molecular-vapor-deposited on the nickel foam (NF) supported ZIF-67 nanosheets to obtain the composite catalyst, namely DPPF-500/ZIF-67/NF. FePO4/PdC encapsulated the ZIF-67 derived Co/N-doped carbon matrix (CoNC) to form a sandwich structure FePO4/PdC@CoNC. The constructed catalyst shows good performance for OER, requiring an overpotential of only 297 mV to deliver 600 mA/cm2 with a Tafel slope of 42.7 mV dec−1. DFT calculations demonstrate that the synergistic effects between the metal active center and P-doped carbon film reduce the energy barriers and improve electron transport. This method of constructing P-containing catalysts overcomes the demand for additional P sources to realize eco-friendly fabrication and yields a unique structure with good catalytic activity.