Triphenylphosphine-Assisted Exsolution Engineering on Ruddlesden-Popper Perovskites for Promoting Oxygen Evolution

Metal exsolution engineering has been regarded as a promising strategy for activating intrinsically inert perovskite oxide catalysts toward efficient oxygen evolution reaction.Traditional metal exsolution processes on perovskites are often achieved by using the reducing hydrogen gas;however,this is not effective for the relatively stable phase,such as Ruddlesden-Popper perovskite oxides.To address this issue,triphenylphosphine is proposed to be a reduction promotor for accelerating the reduction and migration of the target metal atoms,aiming to achieve the effective exsolution of metallic species from Ruddlesden-Popper-type parent perovskites.Upon oxygen evolution reaction,these exsolved metallic aggregates are reconstructed into oxyhydroxides as the real active centers.After further modification by lowpercentage iridium oxide nanoclusters,the optimal catalyst delivered an overpotential as low as 305 mV for generating the density of 10 mA cm^(-2),outperforming these reported noble metal-containing perovskite-based alkaline oxygen evolution reaction electrocatalysts.This work provides a potential approach to activate catalytically inert oxides through promoting surface metal exsolution and explores a novel class of Ruddlesden-Poppertype oxides for electrocatalytic applications.