Epitaxial growth strategy for construction of Tm3+ doped and [hk1] oriented Sb2S3 nanorods S-scheme heterojunction with enhanced photoelectrochemical performance

With the advantages of high absorption coefficient, non-toxicity and low cost, Sb2S3 shows great potential as a narrow bandgap photocathode in the field of PEC hydrogen production. However, the separation and transportation of photogenerated carriers in the reported Sb2S3 photocathode are inefficient due to its anisotropy and the Fermi level being pinned by deep-level defects. Therefore, Tm3+ doped Sb2S3 nanorods with the selective carrier transport orientation were epitaxially grown on SnSe2 film by a simple hydrothermal strategy to modulate the defect property of Sb2S3, optimize carrier transportation and separation efficiency, and improve the PEC performance of photoelectrodes. Experimental results showed that the doping of Tm3+ weakening the Fermi level pinning while achieving the conversion of Sb2S3 to n-type conducting property. The S-scheme heterojunction formed by Tm3+ doped Sb2S3 nanorods labeled as Sb2S3: Tm3+ and SnSe2 nanosheets provided a stronger driving force to optimize carrier interface transportation. The photocurrent density (−0.91 mA cm−2) is increased about 18 times compared to the pristine Sb2S3 photocathode. This work developed an effective doping strategy to weaken the Fermi level pinning and provided a novel idea for the epitaxial growth of Sb2S3 nanorods to optimize the carrier transportation.