The paired electrolysis via anodic organic oxidation and cathodic hydrogen evolution has been an emerging hydrogen production technology with high efficiency and high values. Nickel oxyhydroxide is a special electrocatalyst that is capable of selectively oxidizing various alcohols, aldehydes, and amines to the corresponding carboxylates and nitriles at more favorable potentials compared to the oxygen evolution reaction. However, its detailed molecular-level mechanism is still in debate, especially for the potential-dependent behavior of some organic substrates. In this study, we revealed that the nickel oxyhydroxide can be dissected into two functional regions with a more facilely oxidized surface for facilitated substrate adsorption and a relatively inert bulk phase for accelerated electron transfer via probe-assisted kinetics and in situ surface-enhanced Raman spectroscopy. The prerequisite of the two regions conceals a universal potential-dependent oxidation behavior for almost all organic substrates. Further combining with the computational investigation unravels the origin of this potential dependence from the exothermic O/N-centered adsorption process on the surface and the rate-limiting proton-coupled electron-transfer (PCET) steps for the C−H bond breaking that demands bulk electron conductivity. This provides a rationale for designing more conductive underlayers to break the intrinsic limitations of nickel oxyhydroxide toward more efficient organic electrooxidation processes.

Neutral water oxidation is a crucial half‐reaction for various electrochemical applications requiring pH‐benign conditions. However, its sluggish kinetics with limited proton and electron transfer rates greatly impacts the overall energy efficiency. In this work, we created an electrode/electrolyte synergy strategy for simultaneously enhancing the proton and electron transfers at the interface toward highly efficient neutral water oxidation. The charge transfer was accelerated between the iridium oxide and in situ formed nickel oxyhydroxide on the electrode end. The proton transfer was expedited by the compact borate environment that originated from hierarchical fluoride/borate anions on the electrolyte end. These concerted promotions facilitated the proton‐coupled electron transfer (PCET) events. Due to the electrode/electrolyte synergy, Ir−O and Ir−OO− intermediates could be directly detected by in situ Raman spectroscopy, and the rate‐limiting step of Ir−O oxidation was determined. This synergy strategy can extend the scope of optimizing electrocatalytic activities toward more electrode/electrolyte combinations.

Neutral water oxidation is a crucial half‐reaction for various electrochemical applications requiring pH‐benign conditions. However, its sluggish kinetics with limited proton and electron transfer rates greatly impacts the overall energy efficiency. In this work, we created an electrode/electrolyte synergy strategy for simultaneously enhancing the proton and electron transfers at the interface toward highly efficient neutral water oxidation. The charge transfer was accelerated between the iridium oxide and in situ formed nickel oxyhydroxide on the electrode end. The proton transfer was expedited by the compact borate environment that originated from hierarchical fluoride/borate anions on the electrolyte end. These concerted promotions facilitated the proton‐coupled electron transfer (PCET) events. Due to the electrode/electrolyte synergy, Ir−O and Ir−OO− intermediates could be directly detected by in situ Raman spectroscopy, and the rate‐limiting step of Ir−O oxidation was determined. This synergy strategy can extend the scope of optimizing electrocatalytic activities toward more electrode/electrolyte combinations.