Nb2O5-Ni3N heterojunction tuned by interface oxygen vacancy engineering for the enhancement of electrocatalytic hydrogen evolution activity

The requirement of hydrogen adsorption Gibbs free energy (Delta G(H*)) approximating to 0 eV limits the hydrogen evolution reaction (HER) activity of most electrocatalysts in alkaline media. The construction of interface and defects engineering is an effective strategy to obtain the optimal Delta G(H*). Ni3N exhibits poor HER activity due to its undesirable Delta G(H*). By cooperating with Nb2O5, the d-band center of Ni3N was reduced, improving its catalytic performance. The optimized Nb2O5-Ni3N displays an overpotential of 80 mV at 10 mA cm(-2) and superior activity than the benchmark Pt/C catalyst when the current density is greater than 125 mA cm(-2). Experimental and density functional theory results demonstrate that the improved catalytic activity is because the electronic interaction between Ni and Nb changes the coordination numbers of these two atoms, resulting in oxygen vacancies at the interface. Under the synergistic effect of Nb2O5 and Ni3N, the catalyst exhibits optimal Delta G(H*) and water adsorption energy.

Automated summary

The activity of electrocatalysts is limited by the requirement of hydrogen adsorption Gibbs free energy approximating to 0 eV, which can be optimized through the construction of interface and defects engineering. Ni3N exhibits poor HER activity in alkaline media, but can be improved by cooperating with Nb2O5 to enhance its catalytic performance. The optimized Nb2O5-Ni3N catalyst shows superior activity at high current densities due to the synergistic effect of Nb2O5 and Ni3N resulting in optimal Delta G(H*) and water adsorption energy.