Constructing Heterogeneous Interface by Growth of Carbon Nanotubes on the Surface of MoB 2 for Boosting Hydrogen Evolution Reaction in a Wide pH Range.

Transition metal diborides represented by MoB 2 have attracted widespread attention for their excellent acidic hydrogen evolution reaction (HER). Nevertheless, their electrocatalytic performance is generally unsatisfactory in high-pH electrolytes. Heterogeneous interface engineering is one of the most promising methods for optimizing the composition and structure of electrocatalysts, thereby greatly affecting their electrochemical performance. Herein, a heterostructure, composed of MoB 2 and carbon nanotubes (CNTs), is rationally constructed by boronizing precursors including (NH 4 ) 4 [NiH 6 Mo 6 O 24 ]·5H 2 O (NiMo 6 ) and Co complexes on the carbon cloth (Co,Ni-MoB 2 @CNT/CC). In this method, NiMo 6 is boronized to form MoB 2 by a modified molten-salt-assisted borothermal reduction. Meanwhile, Co catalyzes extra carbon sources to grow CNTs on the surface of MoB 2 . Thanks to the successful production of the heterostructure, Co,Ni-MoB 2 @CNT/CC exhibits remarkable HER performance with a low overpotential of 98.6, 113.0, and 73.9 mV at 10 mA cm -2 in acidic, neutral, and alkaline electrolytes, respectively. Notably, even at 500 mA cm -2 , the electrochemical activity of Co,Ni-MoB 2 @CNT/CC exceeds that of Pt/C/CC in an alkaline solution and maintains over 50 h. Theoretical calculations reveal that the construction of the heterostructure is beneficial to both water dissociation and reactive intermediate adsorption, resulting in superior alkaline HER performance.