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/Co 3 O 4 was first prepared by calcining the ZIF-8@ZIF-67 in Air. Then, the ternary mix-heterojunction ZnIn 2 S 4 /CdIn 2 S 4 /Co 3 O 4 (CdIn 2 S 4 /Z/C) was first in situ constructed by introducing nano complex ZnO/Co 3 O 4 into the CdIn 2 S 4 precursor solution via a solvent thermal reaction. Overall, the CdIn 2 S 4 /Z/C photocatalyst exhibits excellent performance in the photoconversion of CO 2 and H 2 O, which increased by 18.1%∼34.1% for CO, 36.8%∼73.9% for H 2 , and 21.1%∼40.6% for syngas (CO+H 2 ), respectively, compared with CdIn 2 S 4 . The CdIn 2 S 4 /Z/C-40 shows the highest H 2 -evolution rate of 1661.8 μmolg −1 h −1 , which is 87.5% higher than that of CdIn 2 S 4 (886.3 μmolg −1 h −1 ). The CdIn 2 S 4 /Z/C exhibits higher surface S-vacancy concentration, larger specific surface area, stronger light absorption, and photocurrent density than that of CdIn 2 S 4 . The band structure reveals that the ZnIn 2 S 4 /CdIn 2 S 4 /Co 3 O 4 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 CO 2 and H 2 O.