Fabrication of novel all-solid-state Z-scheme heterojunctions of 3DOM-WO₃/Pt coated by mono-or few-layered WS₂ for efficient photocatalytic decomposition performance in Vis-NIR region

In this work, novel three dimensional ordered macroporous (3DOM) WO₃/Pt/WS₂ all-solid-state Z-scheme heterojunctions were firstly synthesized by gas phase chemical reduction methods. The layer numbers of coated WS₂ on the skeleton of 3DOM Z-scheme heterojunctions are easily tuned by controlling the amount of sulfur powder, and the energy band structure of WS₂ can be thus artificial turned, leading to distinct visible and near infrared (Vis-NIR) light absorption and charge separation ability of the as-prepared 3DOM samples. The experimental results show that the obtained 3DOM-WO₃/Pt sample coated by 2–3 layered WS₂ exhibits high photoelectric conversion ability, unbelievable photocurrent signal and excellent photodegradation activity, suggesting that the high separation efficiency of photon-generated charge can result in the superior photocatalytic performance of 3DOM-WO₃/Pt/WS₂. The selective photo-deposition of Au is used to proof the possible mechanism of charges transfer, and the results show that Z-scheme heterojunction can endow 3DOM-WO₃/Pt/WS₂ sample with a unique charges migration path, in which the photogenerated electrons on the conduction band (CB) of WO₃ and the holes on the valence band (VB) of WS₂ are easily transferred into metal Pt to recombine and the lifetime of electrons on the CB of WS₂ as well as the holes on the VB of WO₃ are strongly prolonged.