Hydrogen Evolution by Ni₂P Catalysts Derived from Phosphine MOFs

Strategies to improve the catalytic efficiency of the hydrogen evolution reaction (HER), an integral electrochemical reaction in solar-to-hydrogen technologies, frequently include the use of porous precursors to make electrocatalysts. Researchers have used high-surface-area metal organic frameworks (MOFs) as precursors to synthesize active metal phosphide catalysts, but these MOFs must be mixed with a second phosphorus precursor to produce the metal phosphide. In this work, we synthesized nickel phosphide catalysts in one step from single-MOF precursors. Our MOFs contain phosphine coordination sites within the organic framework, allowing us to produce metal phosphide catalysts without the need for an exogenous phosphorus source. This strategy is convenient because the use of a crystalline precursor may offer the possibility of greater control over both the phase and resulting properties of the as-formed metal phosphide materials. The best MOF-derived Ni2P HER electrocatalyst delivered current densities of −10 mA/cm2 at an overpotential of 120 mV on glassy carbon substrate electrodes. A long-term test showed our sample could evolve hydrogen for over 1 h under physically and chemically harsh conditions.