Polyvinyl alcohol protected Mo2C/Mo2N multicomponent electrocatalysts with controlled morphology for hydrogen evolution reaction in acid and alkaline medium

Highlights: • PVA-Mo₂C/Mo₂N nanospheres with surface roughness are synthesized via polyvinyl alcohol protection. • PVA-Mo₂C/Mo₂N exhibits superior electrocatalytic performance for hydrogen evolution reaction. • PVA-Mo₂C/Mo₂N nanospheres function effectively in both acid and alkaline medium. • The enhanced intrinsic activity and surface area of PVA-Mo₂C/Mo₂N originates from controlled composition and morphology. Herein, PVA-Mo₂C/Mo₂N nanospheres with surface roughness are synthesized via a polyvinyl alcohol (PVA) involved approach and used for hydrogen evolution reaction (HER). The average crystallite size of the PVA protected nMo₂CN nanospheres (6.1 nm) is one third of that of the PVA-Mo₂C/Mo₂N without PVA protection (17.9 nm). At 10 mA cm⁻² current density, the as-synthesized PVA-Mo₂C/Mo₂N nanospheres with surface roughness exhibit HER overpotentials of 132 mV and 142 mV with corresponding Tafel slope of 51.8 mV dec⁻¹ and 50.4 mV dec⁻¹ in acid and alkaline medium, respectively. This high apparent activity can be attributed to the high intrinsic activity originated from the adjacent surface active sites of Mo₂C and Mo₂N as well as the large ECSA of PVA-Mo₂C/Mo₂N nanospheres with surface roughness.