Keywords: hydrogen evolution, band engineering
Summary:The hydrogen evolution reaction (HER) is essential for sustainable energy generation. Generally, indirect band gap and chemical inertness restrict such catalytic activity for transition metal dichalcogenides (TMDs). Herein, we have employed 1T-2H phase MoSe2/MoO3 as a catalyst, including pH universal hydrogen evolution (HER), where multiple active sites have been involved in the catalytic activity. The band engineering suggests reduced work function and shifting valance band near Fermi level boosts the electron transfer between MoSe2-MoO3 heterostructure. Furthermore, theoretical calculation revealed that in and out of plane O2- are more favorable sites for H adsorption. The lower energy hydrogen spillover from different O2- site to endothermic Se and Mo5+/6+ sites facilitates hydrogen adsorption-desorption mechanism. Such an effect enhances the active surface area showing excellent acidic HER activity with an overpotential of 200 mV at 10 mA cm-2. Post XPS analyses and masking of active sites with SCN- suggest Se2-, O2- and Mo5+/6+ are catalytic sites in acidic and alkaline HER respectively. Our strategy displays that electronic band structure, d band center, adsorption energy, multiple catalytic active sites, and H spillover mechanism for MoSe2-MoO3 catalyst, which yields benchmark HER activity in pH universal hydrogen production than pure 2H-MoSe2 based materials.