Quasi-Monolayer Ag2Se/1T-WSe2 Nanosheets for Enhanced Electrocatalytic Hydrogen Evolution and Charge Storage

With a dual strategy of phase-interface engineering, monolayer (1L)-1T-WSe2 integrated with Ag2Se nanoparticles (NPs) is in situ fabricated as quasi-monolayer Ag2Se/1L-1T-WSe2 hybrid nanosheets via a one-pot oleylamine-colloidal reaction. The Ag2Se NPs direct the growth of 1L-1T-WSe2 nanosheets forming the quasi-monolayer hybrid nanosheets by lodging in the interlayer spaces of WSe2 while the Ag2Se NPs being in a superionic conductor state diffuse rapidly and prevent the growth of piled-up multilayered WSe2 nanosheets. Due to the formation of quasimonolayer Ag2Se/1L-1T-WSe2 nanosheets, many more side edges are exposed. Intensive studies illustrated that the quasi-monolayer Ag2Se/1L-1T-WSe2 hybrid nanosheets provide increased surface area and active sites as compared with isolated Ag2Se and WSe2. The hybrid nanosheets demonstrated excellent catalytic properties for hydrogen evolution reaction (HER) with overpotentials (eta(10)) of 163 and 140 mV in acidic and basic conditions, respectively, and an outstanding alkaline supercapacitance of 1674 F g(-1) at 1 A g(-1). Meanwhile, X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) determinations revealed that the quasi-monolayer hybrid nanosheets with enhanced electronic modulation could promote H+ adsorption/H-2 desorption and accelerate the transport and separation of charge on the interface of heterostructured catalyst along with the electrode surface so as to exhibit outstanding electrochemical performances for HER and pseudocapacitance.