Facilitating the rapid Grotthuss diffusion of OH⁻ in electrolyte for accelerated oxygen evolution reaction

Faster OH⁻ transfer for efficient adsorption on catalysis is key to accelerating the oxygen evolution reaction (OER). The diffusion of OH⁻ in electrolyte mainly involves two mechanism which is dependent on the water coordination number (CN): Grotthuss diffusion (4 CN) and vehicular diffusion (5 CN). The Grotthuss diffusion is much faster but the vehicular diffusion of OH⁻ is predominant in the electrolyte. Herein, negatively charged kaolin, which are simply dispersed in the electrolyte, are utilized to provide surface electrostatic attraction to H₂O and repulsion to OH⁻ to reduce the OH⁻ CN from 5 to 4 for rapid Grotthuss diffusion. This contributes to the accelerated OH⁻ adsorption which facilitates the charge transfer, the formation and the deprotonation of *OOH leading to enhanced OER performance. The OH⁻ CN recovery from 4 to 5 is proved quite slow after leaving the kaolin surface, breaking the limitation that kaolin must be on the catalyst surface. This strategy exhibits universality for various electrocatalysts with reduced overpotential by 10–246 mV at 10 mA cm⁻². We provide a clean, simple and low-cost way to promote the industrial development of alkaline water electrolysis.