Termination-acidity tailoring of molybdenum carbides for alkaline hydrogen evolution reaction
Zhi‐Gang Chen, Minghao Yang, Yifan Li, Wenbin Gong, Juan Wang, Tong Liu, Chunyu Zhang, Shuang Hou, Guang Yang, Hao Li, Ye Jin, Chunyan Zhang, Zhongqing Tian, Fancheng Meng, Yi Cui
Abstract
Transition-metal carbides have been advocated as the promising alternatives to noble-metal platinum-based catalysts in electrocatalytic hydrogen evolution reaction over half a century. However, the effectiveness of transition-metal carbides catalyzing hydrogen evolution in high-pH electrolyte is severely compromised due to the lowered proton activity and intractable alkaline-leaching issue of transition-metal centers. Herein, on the basis of validation of molybdenum-carbide model-catalyst system by taking advantage of surface science techniques, Mo2C micro-size spheres terminated by Al3+ doped MoO2 layer exhibit a notable performance of alkaline hydrogen evolution with a near-zero onset-potential, a low overpotential (40 mV) at a typical current density of 10 mA/cm2, and a small Tafel slope (45 mV/dec), as well as a long-term stability for continuous hydrogen production over 200 h. Advanced morphology and spectroscopy characterizations demonstrate that the local -Al-OH-Mo- structures within Al-MoO2 terminations serve as strong Brønsted acid sites that accelerate the deprotonation kinetics in alkaline HER process. Our work paves an interesting termination-acidity-tailoring strategy to explore cost-effective catalysts towards water electrolysis and beyond. Exploring low-cost, efficient catalysts to replace platinum is crucial for electrocatalytic hydrogen generation. Here, the authors report a termination-acidity strategy that boosts the activity of molybdenum carbides, achieving a low overpotential and sustaining hydrogen generation for over 200 h.