Phase‐Modulated Band Alignment in CdS Nanorod/SnSx Nanosheet Hierarchical Heterojunctions toward Efficient Water Splitting

Abstract CdS is a promising visible light response photoanode of photoelectrochemical (PEC) water splitting, but it remains a great challenge for practical application, due to the photohole‐induced self‐corrosion, and sulfide/sulfite ions as hole scavengers are always necessary for stable solar hydrogen generation. Herein, a CdS/SnS x nanorods/nanosheets hierarchical heterostructure with novel phase‐engineered band alignment is rationally designed via a two‐step solution reaction route for PEC water splitting. In the Na 2 SO 4 aqueous electrolyte without any hole scavengers, compared with the pristine CdS, the CdS/SnS x photoanode achieves a remarkably enhanced photocurrent density of 1.59 mA cm −2 and a considerable stability at bias potential 1.23 V versus reversible hydrogen electrode (RHE) under simulated sunlight. It is proposed that the deposited SnS x nanosheets not only act as protective layers to restrain the photocorrosion of CdS, but also facilitate the charge separation in CdS by the virtue of the Type II heterojunction formed between CdS and SnS x .