Atomic-Level Platinum Filling into Ni-Vacancies of Dual-Deficient NiO for Boosting Electrocatalytic Hydrogen Evolution

Developing low-cost and high-efficiency catalysts for sustainable hydrogen production through electrocatalytic hydrogen evolution reaction (HER) is crucial yet remains challenging. Here, a strategy is proposed to fill Ni-vacancy (Ni-v) sites of dual-deficient NiO (D-NiO-Pt) deliberately created by Ar plasma with homogeneously distributed Pt atoms driven by oxygen vacancies (O-v). The incorporated Pt atoms filling the Ni-v reduce the formation energy to increase crystal stability, and subsequently combine with additional O-v to tune the electronic structure of the surrounding Ni sites. Thus, a more ideal hydrogen adsorption free energy (Delta G(H*)) closer to 0 of Ni sites and Pt sites can be achieved. As a result, the D-NiO-Pt electrode achieves superior mass activity of approximate to 1600 mA mg(-1) (normalized by platinum) and nearly negligible loss of activity during long-term operation, which is much better than as-prepared Pt-containing NiO catalysts without plasma treatment. A low overpotential of 20 mV is required for the D-NiO-Pt at 10 mA cm(-2) in alkaline HER, outperforming that of the commercial Pt/C. In addition, the universal access to the other Ni-based compounds including nickel phosphide (Ni2P), nickel sulfide (Ni0.96S), and nickel selenide (NiSe2) is also demonstrated by employing a vacancy-driven Pt filling mechanism.

Automated summary

A strategy is proposed to enhance the activity of NiO catalysts by filling Ni-vacancy sites. This can be achieved by using Ar plasma and oxygen vacancies. The filled Pt atoms increase crystal stability and tune the electronic structure. Experimental results show that the Pt-filled D-NiO-Pt electrode exhibits superior mass activity and long-term stability.