CdS/CdSe Core–Shell Nanorod Arrays: Energy Level Alignment and Enhanced Photoelectrochemical Performance

Novel CdS/CdSe core–shell nanorod arrays were fabricated by a chemical bath deposition of CdSe on hydrothermally synthesized CdS nanorods. The CdS rods were hexagonal phase faced and the top of the rod was subulate. After the chemical bath deposition approach, CdS nanorod arrays were encapsulated by a uniform CdSe layer resulting enhanced absorbance and extended absorption edges of the films. A tandem structure of the energy bands of CdS/CdSe was also formed as a result of the Fermi level alignment, which is a benefit to the efficient separation of photogenerated charges. CdS/CdSe core–shell arrays gave a maximum photocurrent of 5.3 mA/cm², which was 4 and 11 times as large as bare CdS and CdSe, respectively.