Discovering highly efficient and stable non-precious metal catalysts for the oxygen evolution reaction (OER) is crucial for energy conversion in water splitting. However, preparing high-performance OER catalysts and elucidating the structural changes in the process are still challenging. Herein, we synthesize the NiTe/Ni2P heterostructure and demonstrate the strain engineering of NiTe/Ni2P via the lattice incompatibility between the phosphide and the telluride. The strain engineering of the NiTe/Ni2P heterostructure not only significantly boosts the OER activity but also effectively stabilizes the intrinsic structure of the catalyst after the OER process by using the in situ-produced metal salt as a protection layer. After the OER stability test, no oxyhydroxide phase is observed, and in situ Raman spectroscopy reveals that a voltage-dependent phase transition appears during the OER, which is different from most previously reported Ni-based catalysts, for which the generation of irreversible NiOOH occurs after the OER. Density functional theory calculations further reveal that the tensile strain of Ni2P will inhibit the presence of irreversible phase transitions of Ni2P into NiOOH due to the weak adsorption ability of the oxygen species caused by strain engineering. In short, this work opens a new gate for using strain nanotechnology to design high-performance OER catalysts.
Keywords: heterostructure interface; lattice strain; oxygen evolution reaction; strain engineering; voltage-dependent phase transition; water splitting.