Boosting photocatalytic and SERS performance of n%M−ZnO/CeO2/Ag 3D porous microspheres through a dual modification strategy with interface and doping engineering

Abstract

The application of surface-enhanced Raman scattering (SERS) spectroscopy is widespread in the fields of material science, surface and analytical chemistry due to its distinctive fingerprint effect, rapid detection capabilities, and exceptional trace sensitivity. Among these attributes, the utmost significance lies in the utilization of high-quality SERS substrates. A bifunctional platform featuring high photocatalytic activity and superior SERS activity was developed via a dual modification strategy integrating interface and doping engineering. Utilizing one-step hydrothermal method, ZnO/CeO₂ 3D porous microspheres (PMSs) with varied doping concentrations were fabricated, followed by the photodeposition of Ag nanoparticles to obtain n%M−ZnO/CeO₂/Ag PMSs (M = Ga or Mg) with enhanced catalytic degradation efficiency and SERS activity. The pronounced enhancement is primarily ascribed to the synergistic effects of the surface plasmon resonance (SPR) of Ag nanoparticles, interfacial charge transfer between ZnO, CeO₂ and Ag, and the augmented chemical interactions mediated by defects induced through doping. The optimized 6.25 %M−ZnO/CeO₂/Ag PMSs exhibited remarkable catalytic performance, decomposing rhodamine 6G (R6G) within 8 min and crystal violet (CV) within 6 min, manifesting a potent degradation activity towards organic dye molecules. Notably, the degradation efficiency remained basically unchanged following three consecutive cycles of reuse. As SERS-active substrate, the detection limit for R6G was achieved at 10⁻¹¹ M, demonstrating a fine linear relationship (R² > 0.99) within a concentration range from 10⁻⁶ M to 10⁻¹¹ M. Even after three months of exposure to ambient air, the SERS activity was essentially unaffected, with a retention of 89 %. The detection threshold for the pesticide thiram was found to be as low as 10⁻⁹ M, which is significantly below the national standard. This novel bifunctional catalytic and SERS detection platform, refined through a combination of interfacial and doping modifications, holds great potential for significant applications in environmental monitoring and food safety.