Accelerated exciton dissociation and electron extraction across the metallic sulfide–carbon nitride ohmic interface for efficient photocatalytic hydrogen production

Herein, a MOF derived transition metal sulfide (Co3S4) with a metallic characteristic is introduced to create an ohmic contacted Co3S4–CN heterojunction interface. By virtue of electron injection from the lower work function Co3S4 to the g-CN semiconductor, an intensive interfacial electric field is produced and causes downward band bending of g-CN. This Co3S4–CN heterojunction not only accelerates the exciton dissociation, but also eliminates the potential barrier for majority carrier (electron) extraction from g-CN, which synergistically promotes the charge separation. The Co3S4 mediated performance enhancement in hydrogen production is proven to be comparable with that of noble metal Pt, and the as-obtained CNCo-3 exhibits superior photocatalytic activity in visible light driven hydrogen evolution (∼217.0 μmol g−1 h−1). The findings uncover the fundamental mechanism of metallic sulfide mediated charge separation and pave the way for regulating interface charge separation in photocatalysis through the use of other metallic sulfides (e.g. Ni2S).