Concerted Steering of Interfacial Water and Hydrogen Spillover via Optimum Orbital Hybridization for Alkaline Water Electrocatalysis
Hongqing Zhao, Rong Xin, Ying Yuan, Yijiang Liu, Li Luo, Xiuyun Wang, Shuzhi Liu, Diye Wei, Mei Yang, Bei Liu, Shujiang Ding, Zhiqun LinABSTRACT
Developing efficient non‐precious electrocatalysts for hydrogen evolution reaction (HER) in alkaline media is critical for industrial water electrolysis, yet sluggish water dissociation and inefficient hydrogen transfer kinetics remain key bottlenecks. Herein, we report NiCo/MoO 2 co‐implanted in N‐doped carbon spheres (NiCo/MoO 2 ‐NC) as a model electrocatalyst to unravel how 3d‐4d‐2p orbital hybridization dictates dynamic interface water evolution and hydrogen spillover. In situ Raman spectroscopy reveals a dynamic transformation of hydrogen‐bonded water into free water, enabling self‐modulation of interfacial water that promotes water dissociation and ensures sufficient protons supply. Density functional theory (DFT) calculations show that orbital hybridization regulates d‐band center and interfacial electron redistribution, thereby optimizing water adsorption and dissociation on NiCo. Concurrently, hydrogen spillover from NiCo to MoO 2 balances H* adsorption/desorption, accelerating H 2 evolution kinetics. The catalyst also undergoes surface reconstruction at low applied potential, enhancing oxygen evolution reaction (OER) kinetics. As a result, NiCo/MoO 2 ‐NC exhibits low overpotentials of 32 mV (10 mA cm − 2 ) for HER and 250 mV for OER, and enables an anion exchange membrane water electrolyzer to deliver 500 mA cm −2 at 1.70 V, with stable operation over 500 h. These findings establish orbital hybridization as a key lever for coordinating interfacial water and hydrogen transfer in alkaline electrocatalysis.