Phosphine vapor-assisted construction of heterostructured Ni2P/NiTe2 catalysts for efficient hydrogen evolution

Abstract

Heterostructured catalysts with unique interfaces and properties endow distinct advantages for many electrochemical reactions. Herein, a phosphine (PH₃) vapor-assisted phase and structure engineering strategy is developed for the controllable conversion of non-active NiTe into a heterostructured active Ni₂P/NiTe₂ catalyst for alkaline hydrogen evolution reaction (HER). The crystalline NiTe₂ phase in situ generated in a PH₃ vapor environment and the nanosheet morphology both contribute to the outstanding alkaline HER performance with an overpotential of only 62 mV to achieve a current density of −10 mA cm⁻². Experimental and DFT mechanistic studies suggest the Ni₂P/NiTe₂ interfaces provide abundant exposed active sites. The Ni₂P/NiTe₂ catalyst shows the lowest kinetic barrier for water dissociation and the adsorbed H* can simultaneously bind to two Ni atoms at the interface of Ni₂P/NiTe₂(011), which greatly enhances the H* binding and HER activities. DFT simulation also shows that more electrons transfer from Ni atoms to H* on Ni₂P/NiTe₂(011) (0.22 e⁻) than that on NiTe₂(011) (0.13 e⁻), which explains the enhanced H* binding at the Ni₂P/NiTe₂(011) interface. The PH₃ vapor synthetic approach is also applied to treat other chalcogenide-based materials with low HER activities, such as Ni₃S₂, to create Ni₂P/NiS₂ interfaces for significantly enhanced HER activity.