Defects regulation of Sb2S3 by construction of Sb2S3/In2S3 direct Z-scheme heterojunction with enhanced photoelectrochemical performance

Antimony sulfide (Sb2S3), as a narrow band-gap semiconductor with strong visible light absorption ability, nevertheless due to the existence of a large number of defective energy levels, the application in the field of PEC water splitting was limited. This paper aimed to construct Sb2S3/In2S3 direct Z-scheme heterojunction to effectively eliminate the adverse effect of defective energy level on the photoelectrochemical performance of Sb2S3. Cell-like Sb2S3 thin films were prepared on ITO substrates by simple hydrothermal method, followed by using solvothermal method, the Sb2S3/In2S3 direct Z-scheme heterojunction was successfully constructed. The IPCE values of Sb2S3/In2S3 could reach 10.19 % (735 nm) compared with pure Sb2S3 (4.22 %). Both the separation and injection efficiency could be improved from 3.35 % and 31.69 % to 5.19 % and 61.48 %, respectively. The maximum photocurrent density was 1.24 mA/cm2 at 1.23 V vs. RHE, which was 5.6 times higher than pristine Sb2S3 (0.22 mA/cm2). Moreover, an earlier onset potential was observed (~0.7 V vs. RHE), showing an improvement of 0.3 V when compared to the pristine Sb2S3. This work provided a new idea for the application of antimony chalcogenides in the field of PEC water splitting and the construction of efficient photoelectric devices.