Nanoparticles of cobalt phosphide, CoP, have been prepared and evaluated as electrocatalysts for the hydrogen evolution reaction (HER) under strongly acidic conditions (0.50 M H2SO4, pH 0.3). Uniform, multi-faceted CoP nanoparticles were synthesized by reacting Co nanoparticles with trioctylphosphine. Electrodes comprised of CoP nanoparticles on a Ti support (2 mg cm-2 mass loading) produced a cathodic current density of 20 mA cm-2 at an overpotential of -85 mV. The CoP/Ti electrodes were stable over 24 h of sustained hydrogen production in 0.50 M H 2SO4. The activity was essentially unchanged after 400 cyclic voltammetric sweeps, suggesting long-term viability under operating conditions. CoP is therefore amongst the most active, acid-stable, earth-abundant HER electrocatalysts reported to date. One step closer to Pt: Nanoparticles of cobalt phosphide (CoP) catalyze the hydrogen evolution reaction with high activity and stability under strongly acidic conditions. Its electrocatalytic performance places CoP amongst the best Earth-abundant alternatives to platinum.
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