Scalable neutral H₂O₂ electrosynthesis by platinum diphosphide nanocrystals by regulating oxygen reduction reaction pathways

Despite progress in small scale electrocatalytic production of hydrogen peroxide (H₂O₂) using a rotating ring-disk electrode, further work is needed to develop a non-toxic, selective, and stable O₂-to-H₂O₂ electrocatalyst for realizing continuous on-site production of neutral hydrogen peroxide. We report ultrasmall and monodisperse colloidal PtP₂ nanocrystals that achieve H₂O₂ production at near zero-overpotential with near unity H₂O₂ selectivity at 0.27 V vs. RHE. Density functional theory calculations indicate that P promotes hydrogenation of OOH* to H₂O₂ by weakening the Pt-OOH* bond and suppressing the dissociative OOH* to O* pathway. Atomic layer deposition of Al₂O₃ prevents NC aggregation and enables application in a polymer electrolyte membrane fuel cell (PEMFC) with a maximum r(H₂O₂) of 2.26 mmol h⁻¹ cm⁻² and a current efficiency of 78.8% even at a high current density of 150 mA cm⁻². Catalyst stability enables an accumulated neutral H₂O₂ concentration in 600 mL of 3.0 wt% (pH = 6.6).