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

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.