Intermediate functionalized endogenous proton relays for enhanced oxygen evolution reaction.

Highly efficient oxygen evolution reaction (OER) depends not only on the activity of the metal centers but also on the rapid removal of protons from surface oxygenated intermediates. Although exogenously constructed proton relays can facilitate proton transfer, they often suffer from rapid structural collapse and deactivation under strongly oxidative OER conditions. To address this issue, we propose a plausible novel intermediate functionalization strategy that converts the *OH intermediates generated in situ during the OER process into endogenous proton relays, fundamentally circumventing the deactivation problem of exogenously proton relays. Using a controllable partial reconstruction Ni3S2/NiOOH/CoOOH heterostructure, the retained highly conductive Ni3S2 skeleton triggers electron depletion in the interfacial amorphous layer. Combined in situ Raman spectroscopy and DFT calculations indicate that this electron depletion favors the preferential and strong anchoring of *OH species at specific Ni-Co bridge sites. Subsequent isotope experiments and DFT calculations further support a plausible mechanistic hypothesis in which these anchored *OH species may function as endogenous proton relays, facilitating the deprotonation of oxygenated intermediates on adjacent co sites. Consequently, the catalyst achieves a low overpotential of 139 ± 2 mV at 10 mA cm-2, a small Tafel slope of 37.01 ± 0.45 mV dec-1, and stable operation for 300 h. this study offers new insights into designing accelerated proton transfer pathways under harsh anodic OER conditions.