Enhanced Ammonia electrooxidation over platinum on a ceria-reduced graphene oxide hybrid via cooperative surface and interfacial effects.

Ammonia electrooxidation reaction (AOR) is a promising anodic reaction for hydrogen production, but its performance is still hindered by sluggish kinetics and severe surface poisoning of Pt catalysts. Herein, a Pt/CeO2-rGO catalyst with Pt nanoparticles supported on a ceria-reduced graphene oxide hybrid support is presented for enhanced AOR performance. Among the prepared catalysts with different ceria:graphene oxide (CeO2:GO) mass ratios, Pt/CeO2-rGO-1.0 exhibited the highest AOR activity, delivering a peak mass activity of 175.7 mA mgPt-1 in 1.0 M KOH + 0.1 M NH4Cl, together with improved durability. Mechanistic analyses reveal that oxygen vacancies in CeO2 promote the availability of adsorbed hydroxyl species (OHad), while the Pt-CeO2 interface weakens the adsorption of poisoning species and key AOR intermediates. Differential electrochemical mass spectrometry (DEMS), in situ electrochemical Raman spectroscopy, and density functional theory (DFT) calculations collectively indicate that Pt/CeO2-rGO-1.0 favors reaction routes associated with the Gerischer-Mauerer pathway and suppresses the accumulation of nitrogen oxide (NOx)-related poisoning intermediates during AOR. These findings demonstrate that integrating oxygen-vacancy-rich CeO2 with conductive rGO is an effective strategy to enhance AOR activity and durability in Pt-based electrocatalysts.