Purposefully construction of ZnIn2S4/CdIn2S4/Co3O4 synergistic mix-heterojunction for enhanced CO2 photoconversion and H2 evolution reaction via cascade charge transfer

The high-dispersed nano complex ZnO/Co3O4 was first prepared by calcining the ZIF-8@ZIF-67 in Air. Then, the ternary mix-heterojunction ZnIn2S4/CdIn2S4/Co3O4 (CdIn2S4/Z/C) was first in situ constructed by introducing nano complex ZnO/Co3O4 into the CdIn2S4 precursor solution via a solvent thermal reaction. Overall, the CdIn2S4/Z/C photocatalyst exhibits excellent performance in the photoconversion of CO2 and H2O, which increased by 18.1%∼34.1% for CO, 36.8%∼73.9% for H2, and 21.1%∼40.6% for syngas (CO+H2), respectively, compared with CdIn2S4. The CdIn2S4/Z/C-40 shows the highest H2-evolution rate of 1661.8 μmolg−1h−1, which is 87.5% higher than that of CdIn2S4 (886.3 μmolg−1h−1). The CdIn2S4/Z/C exhibits higher surface S-vacancy concentration, larger specific surface area, stronger light absorption, and photocurrent density than that of CdIn2S4. The band structure reveals that the ZnIn2S4/CdIn2S4/Co3O4 forms a tandem internal electric field at the double heterojunction interface, which is beneficial to improve the migration of photocarrier. This work provides a feasible strategy for constructing synergistic mix-heterojunction photocatalyst for photoconversion of CO2 and H2O.