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 neutral phosphate-buffered electrolyte solution 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.