Hydrothermal synthesis of bismuth-doped tungsten trioxide (Bi-WO₃) for photocatalytic hydrogen production application

In this report, we proposed the hydrothermal synthesis of bismuth doped tungsten trioxide (Bi-WO₃) for H₂ evolution under visible light. The X-ray diffraction (XRD) study suggested the good phase purity and crystalline nature of the prepared Bi-WO₃. The scanning electron microscope (SEM) revealed that Bi-WO₃ are consists of plates like surface morphology. The ultraviolet–visible (UV–vis) spectroscopy showed that Bi-WO₃ has band gap of 2.69 eV whereas pristine WO₃ has 2.6 eV. It is confirmed that Bi-doping increases the optical band gap of the Bi-WO₃. The Bi-WO₃ (catalyst dose = 5 mg) showed H₂ production rate of 104.2 µmol/g/h which is higher than that of pristine WO₃ (73.6 µmol/g/h). Furthermore, Bi-WO₃ (catalyst dose = 30 mg) showed improved H₂ production rate of 334.7 µmol/g/h. The Bi-WO₃ (30 mg) + 4 wt% Pt exhibited the highest H₂ production rate of 637.8 µmol/g/h. It is believed that presence of Pt as cocatalyst boosted the H₂ evolution rate. The synthesized photocatalyst also demonstrated good stability which suggested its reusability up to four cycles.