Probing the Stability of Ni2P Nanoparticle Electrocatalysts via Operando Benchtop X-ray Absorption Spectroscopy

Earth-abundant catalysts are necessary for the global electrification of the petrochemical industry. Ni₂P is an earth-abundant electrocatalyst that has already been shown to catalyze various reactions, including hydrogen evolution and nitrate reduction. However, Ni₂P is susceptible to corrosion. In this study, we investigate the electrochemical corrosion of Ni₂P nanoparticles through anodic polarization experiments in acidic, neutral, and basic pH electrolytes and dive deeper into the corrosion mechanism of Ni₂P nanoparticles in a neutral phosphate-buffered electrolyte via laboratory-based operando Ni K-edge X-ray absorption spectroscopy. Our results demonstrate that Ni₂P nanoparticles corrode significantly before achieving a passive surface. The corrosion follows a phosphate-first pathway, followed by the rapid oxidation of excess Ni to form a passive surface. Approximately 80–90% of Ni dissolves before passivation is achieved. Future work with Ni₂P should consider the chemical structure of its surface in aqueous conditions and take advantage of its anodic passivation.