Scalable neutral H 2 O 2 electrosynthesis by platinum diphosphide nanocrystals by regulating oxygen reduction reaction pathways.

Despite progress in small scale electrocatalytic production of hydrogen peroxide (H ₂ O ₂ ) using a rotating ring-disk electrode, further work is needed to develop a non-toxic, selective, and stable O ₂ -to-H ₂ O ₂ electrocatalyst for realizing continuous on-site production of neutral hydrogen peroxide. We report ultrasmall and monodisperse colloidal PtP ₂ nanocrystals that achieve H ₂ O ₂ production at near zero-overpotential with near unity H ₂ O ₂ selectivity at 0.27 V vs. RHE. Density functional theory calculations indicate that P promotes hydrogenation of OOH* to H ₂ O ₂ by weakening the Pt-OOH* bond and suppressing the dissociative OOH* to O* pathway. Atomic layer deposition of Al ₂ O ₃ prevents NC aggregation and enables application in a polymer electrolyte membrane fuel cell (PEMFC) with a maximum r(H ₂ O ₂ ) 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 H ₂ O ₂ concentration in 600 mL of 3.0 wt% (pH = 6.6).