Phosphate Ion Functionalization of Perovskite Surfaces for Enhanced Oxygen Evolution Reaction

Recent findings revealed that surface oxygen can participate in the oxygen evolution reaction (OER) for the most active catalysts, which eventually triggers a new mechanism for which the deprotonation of surface intermediates limits the OER activity. We propose in this work a "dual strategy" in which tuning the electronic properties of the oxide, such as La_1-xSr_xCoO_3-δ, can be dissociated from the use of surface functionalization with phosphate ion groups (P_i) that enhances the interfacial proton transfer. Results show that the P_i functionalized La_0.5Sr_0.5CoO_3-δ gives rise to a significant enhancement of the OER activity when compared to La_0.5Sr_0.5CoO_3-δ and LaCoO₃. We further demonstrate that the P_i surface functionalization selectivity enhances the activity when the OER kinetics is limited by the proton transfer. Finally, this work suggests that tuning the catalytic activity by such a "dual approach" may be a new and largely unexplored avenue for the design of novel high-performance catalysts.