The collaborative mechanism of surface S-vacancies and piezoelectric polarization for boosting CdS photoelectrochemical performance

Abstract Direct conversion of solar energy into chemical energy by means of photoelectrochemical (PEC) water splitting holds great potential in renewable energy generation. However, the severe photo-generated carriers recombination and deficient active sites, as the two major obstacles, blocks the PEC water splitting reduction. Herein, we fabricated CdS photoanodes and employ the piezoelectric polarization as built-in electric field for facilitating the photo-generated carriers. Furthermore, S-vacancies are introduced into CdS photoanodes to supply abundant active sites and reduce the band gap of CdS. More importantly, the collaborative mechanism of S-vacancies and piezoelectric polarization for boosting PEC performance of CdS photoanodes is reveled in our study: S-vacancies sites are easier to become the stress point for stimulating the piezoelectric polarization under external force; the number of active sites further increase and S-vacancies produced electrons participate in water splitting reaction during piezoelectric polarization. The mechanism can tackle above-mentioned key challenges and our work provides a promising strategy for designing high efficiency photoelectrodes in PEC water splitting.