Ultrathin g-PAN/PANI-encapsulated Cu nanoparticles decorated on SrTiO3 with high stability as an efficient photocatalyst for the H2 evolution and degradation of 4-nitrophenol under visible-light irradiation

Abstract

Copper-based photocatalysts have attracted considerable attention because of their great prospects in photochemical conversions. However, there are still challenges faced during the preparation of copper-based photocatalysts with have high catalytic efficiency and high stability. In this study, polyaniline (PANI) was doped in an ultra-thin graphitized polyacrylonitrile (g-PAN) layer (denoted as CI), and Cu nanoparticles (NPs) were wrapped in the CI layer encapsulated on SrTiO₃ (STO), which is designed as an efficient and low-cost photocatalyst for photocatalytic hydrogen production under visible light irradiation. Benefiting from the unique CI layer structure, the optimized Cu@CI/STO photocatalytic hydrogen evolution rate obtained was 371 μmol g⁻¹ h⁻¹, which is higher than the hydrogen evolution rate of Cu@g-PAN/STO (265.25 μmol g⁻¹ h⁻¹). Moreover, the CI layer demonstrated a quasi-cocatalyst effect. The ultra-thin CI layer not only protects the Cu NPs from oxidation but also promotes charge separation, which distinctly boosts H₂ evolution, as indicated by the photoluminescence emission spectra, EIS Nyquist diagram and Mott–Schottky diagram. In addition, the degradation rate of Cu@CI/STO is approximately 4-fold higher than that of Cu/STO in the photocatalytic degradation of 4-nitrophenol under visible light. This study delivers a new method to protect Cu NPs and demonstrates the prospect for the rational design of copper-based photocatalysts with high stability and efficiency.