In Situ Construction of Direct Z-Scheme CsxWO3/CsPbBr3 Heterojunctions via Cosharing Cs Atom

To make full use of solar energy and achieve effective separation of photogenerated carriers, semiconductor heterojunction engineering is becoming increasingly significant nowadays. Herein, Cs x WO 3 /CsPbBr 3 heterojunctions via cosharing the Cs atom are synthesized by a facile acid solution method, which involves the in situ growth of CsPbBr 3 nanoparticles on the surface of Cs x WO 3 nanorods. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) tests confirm that a high-quality interface with strong interaction between Cs x WO 3 and CsPbBr 3 is constructed successfully. Thus, a direct Z-scheme charge transfer pathway is built in such close-contact heterojunctions, which can not only effectively prevent the recombination of photogenerated carriers, but also preserve the carriers with higher redox abilities, as confirmed by electron spin resonance (ESR) as well as Kelvin probe force microscopy (KPFM). As a proof of concept, the photocatalytic hydrogen production performance of Cs x WO 3 /CsPbBr 3 is evaluated in ethyl acetate, and a 17-fold enhancement in hydrogen production rate as compared with pristine Cs x WO 3 is obtained, verifying the effective charge separation in such heterojunctions. Herein, a new idea for in situ synthesis of high-quality perovskite-based heterojunctions is provided, which will broaden their optoelectrical applications.