Confining Pd Nanoparticles and Atomically Dispersed Pd into Defective MoO3 Nanosheet for Enhancing Electro- and Photocatalytic Hydrogen Evolution Performances.

Interface engineering of two-dimensional (2D) transition-metal composites for activating plane and edge sites is a significant yet step challenging in boosting their performance for hydrogen evolution reaction (HER). Herein, two-dimensional (2D) MoO3 with petal-shaped nanosheets confining Pd nanoparticles (Pd@MoO3 heterostructure) was prepared via an efficient solvothermal and subsequently hydrogen reduction processes. The atomically dispersed Pd-substituted sites in the interface of Pd nanoparticles and 2D MoO3 lattices significantly play an important role in enhancing the electrocatalytic and photocatalytic performances of the Pd@MoO3 heterostructure. As a result, the Pd@MoO3 heterostructure exhibits a high HER catalytic activity with an overpotential (η) of 71 mV to achieve a current density of 10 mA cm-2 and an extremely low Tafel slope of 42.8 mV dec-1 in 0.5 M H2SO4 solution. Furthermore, the photoresponse of the Pd@MoO3 heterostructure is about 3 times higher than that of the MoO3 nanosheets. This work highlighted a strategy of interface engineering for highly efficient cost-effective catalyst for hydrogen evolution by electric and solar energy conversion.