Ferrocene-induced switchable preparation of metal-nonmetal codoped tungsten nitride and carbide nanoarrays for electrocatalytic HER in alkaline and acid media

Transition metal nitride/carbide (TMN/C) have been actively explored as low-cost hydrogen evolution reaction (HER) electrocatalysts owing to their Pt-like physical and chemical properties. Unfortunately, pure TMN/C suffers from strong hydrogen adsorption and lacks active centers for water dissociation. Herein, we developed a switchable WO₃-based in situ gas–solid reaction for preparing sophisticated Fe-N doped WC and Fe-C doped WN nanoarrays. Interestingly, the switch of codoping and phase can be effectively manipulated by regulating the amount of ferrocene. Resultant Fe-C-WN and Fe-N-WC exhibit robust electrocatalytic performance for HER in alkaline and acid electrolytes, respectively. The collective collaboration of morphological, phase and electronic effects are suggested to be responsible for the superior HER activity. The smallest |ΔG_H*| value of Fe-N-WC indicates preferable hydrogen-evolving kinetics on the Fe-N-WC surface for HER under acid condition, while Fe-C-WN is suggested to be beneficial to the adsorption and dissociation of H₂O for HER in alkaline electrolyte.