Cu3P/PAN derived N-doped carbon catalyst with non-toxic synthesis for alkaline hydrogen evolution reaction

Abstract

To utilize hydrogen as an energy carrier to store surplus electricity, it is necessary to develop a highly efficient and low-cost hydrogen evolution reaction (HER) catalyst for water electrolysis. This work presents an alkaline HER catalyst composed of earth-abundant elements. Through a one-step facile and non-toxic process that combines the phosphorization of copper and the cyclization of polyacrylonitrile (PAN), copper phosphide (Cu₃P) particles embedded in nitrogen-doped carbon were synthesized (Cu₃P/N–C). In the complex structure, Cu₃P is catalytically active towards the HER and N-doped carbon connects the Cu₃P particles electrically and physically. Thus, the incorporation of N-doped carbon simply by adding PAN to a phosphorus precursor improves the electrical conductivity and structural integrity of the Cu₃P electrode during the HER. To achieve the best HER activity, the P-to-PAN ratio was optimized. Cu₃P/N–C prepared on copper foam showed HER overpotentials of 211.1 and 301.8 mV to obtain corresponding current density of 10 and 50 mA cm⁻² in a 1 M KOH solution. At the current density of 10 mA cm⁻², the HER overpotential was stably maintained from 211.1 to 222.1 mV for 24 h. In addition to the enlarged electrochemical active surface area (ECSA), the synergistic effects of the disordered carbon structure formed by the influence of the P source result in the superior performance outcomes of Cu₃P/N–C.