Breaking the linear scaling limit in multi-electron-transfer electrocatalysis through intermediate spillover

Abstract

The linear scaling relationships between the adsorption energies of multiple intermediates constrain the maximum reaction activity of heterogeneous catalysis. Here we propose an intermediate spillover strategy to decouple the elementary electron-transfer steps in an electrochemical reaction by building a bi-component interface, thereby independently tuning the corresponding intermediate adsorption at an individual catalytic surface. Taking the electrocatalytic oxygen reduction reaction as an example, oxophilic sites are preferable for activating oxygen molecules, then the adsorbed OH* intermediates spontaneously migrate to the adjacent sites with a weaker oxygen binding energy, where OH* intermediates are further reduced and desorbed to complete the overall catalytic cycle. Consequently, the designed Pd/Ni(OH)₂ catalyst can remarkably elevate the half-wave potential of the oxygen reduction reaction to ~70 mV higher than that of the Pt/C catalyst, surmounting the theoretical overpotential limit of Pd. This design principle highlights an opportunity for utilizing intermediate spillover to break the ubiquitous scaling relationships in multi-step catalytic reactions.