CuWO4–ZnO heterojunction for the enhancement of photocatalytic clofibric acid degradation and hydrogen production

Abstract

Photocatalytic technology designed to generate green hydrogen and remove organic contaminants from water had been advancing swiftly. This study effectively employed hydrothermal method to create CuWO₄ (CWO)–ZnO heterojunction with different weight ratios namely, CWO, ZnO, 5 wt.% CWO–ZnO, 10 wt.% CWO–ZnO, and 15 wt.% CWO–ZnO. The crystalline structure was determined to be hexagonal for ZnO and anorthic for CWO. Morphology was found to be agglomeration of diminutive CWO particles over ZnO. Elemental composition was confirmed by XPS and EDAX analysis. Optical properties were analyzed by UV–Visible spectroscopy and photoluminescence studies. Photocatalytic clofibric acid (CA) degradation and hydrogen production were studied for the obtained samples. Among the samples, 10 wt.% CWO–ZnO exhibited the highest photodegradation efficiency of 96.41% under 180 min illumination with reaction rate constant(k) of 15.22 × 10^–3 min⁻¹ (exceeding ZnO by 3.26 and CuWO₄ by 2.65) and hydrogen generation of 1342 µmol yield for 5 h (exceeding ZnO by 4.32 and CuWO₄ by 3.81). The best-performing 10 wt.% CWO–ZnO demonstrated exceptional reusability over eight successive photocatalytic assessments. Scavenging experiments revealed the active radicals namely, hydroxyl radicals and holes. The photoreaction mechanism responsible for significant enhancement of efficiency is elucidated.