Modulating the Electrocatalytic Performance of Palladium with the Electronic Metal–Support Interaction: A Case Study on Oxygen Evolution Reaction

The present work reports a general approach to improve the electrocatalytic property of noble metal through regulating its electron status by introducing the electronic metal–support interaction (EMSI). As a case study, the catalytic activity of metallic Pd toward oxygen evolution reaction (OER) in alkaline solution has been significantly promoted by stabilizing Pd^δ+ oxidic species at the interface of the Pd–metal oxide support with the help of EMSI effect, suggesting an intrinsic advantage of Pd^δ+ in driving OER. We further demonstrate that the chemical state of Pd^δ+ can be easily modulated in the range of 2+ to 3+ by changing the metal oxide support, interestingly, accompanied by a clear dependence of the OER activity on the oxidation state of Pd^δ+. The high Pd³⁺ species-containing Fe₂O₃/Pd catalyst has fed an impressively enhanced OER property, showing an overpotential of 383 mV at 10 mA cm^–2 compared to those of >600 mV on metallic Pd and 540 mV on Fe₂O₃/glassy carbon. The greatly enhanced OER performance is believed to primarily derive from the distinctive improvement in the adsorption of oxygenated intermediates (e.g., *OH and *OOH) on metal-oxide/Pd catalysts. Moreover, similar EMSI induced improvements in OER activity in alkaline solution are also achieved on both of the Fe₂O₃/Au and Fe₂O₃/Pt, which possess the oxidic species of Au³⁺, and Pt²⁺ and Pt⁴⁺, respectively.