?????????????????????One-pot solvothermal synthesis of flower-like Fe-doped In2S3/Fe3S4 S- scheme hetero-microspheres with enhanced interfacial electric field and boosted visible-light-driven CO2 reduction

S-scheme heterojunctions hold great potential for CO(2 )photoreduction into solar fuels, but their activities are severely limited by the low efficiency of interfacial charge transfer. In this work, a facile one-pot solvothermal reaction has been developed to dope Fe into flower-like In2S3/Fe3S4 hetero-microspheres (Fe-In2S3/Fe3S4 HMSs), which are demonstrated as an efficient S-scheme photocatalyst for visible-light -driven CO2 photoreduction. The doping of Fe not only reduces the bandgap of In2S3 and thus extends the optical response to the visible-light region, but also increases the densities of donors and sulfur vacancies, which leads to an elevated Fermi level (E-f). The difference of E-f between In2S3 and Fe3S4 is enlarged and their band bending at the interface is therefore enhanced, which results in promoted car-riers transfer in the S-scheme pathway due to the reinforced interfacial electric field. Moreover, Fe -doped In2S3 reduces the formation energy of the *CO intermediate, which thermodynamically favors the CO evolution at the surface. As a result, the Fe-In2S3/Fe3S4 HMSs exhibit a significantly boosted CO2 photoreduction activity in comparison with bare In2S3 and Fe-In2S3 samples. This work demonstrates the great potential of heteroatom-engineered S-scheme photocatalysts for CO2 photoreduction.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this work, Fe-doped flower-like In2S3/Fe3S4 hetero-microspheres (Fe-In2S3/Fe3S4 HMSs) were prepared through a facile one-pot solvothermal reaction and demonstrated as efficient S-scheme photocatalysts for visible-light-driven CO2 photoreduction. The doping of Fe reduced the bandgap of In2S3, extended the optical response to the visible-light region, increased the densities of donors and sulfur vacancies, and elevated the Fermi level. The enhanced interfacial electric field resulted in promoted carrier transfer in the S-scheme pathway. Fe-doped In2S3 also reduced the formation energy of the *CO intermediate, which favored the CO evolution at the surface.