g-C3N4 modified hollow Ag/ZrO2 core–shell composites for enhanced solar photocatalytic degradation and recyclable SERS sensing of thiram and methylene blue

In this study, we demonstrated an efficient solar photocatalyst, g-C 3 N 4 modified hollow Ag/ZrO 2 core–shell composites (Ag/hZrO 2 /CN) using polymethylacrylic acid (PMAA) nanospheres as sacrificial template. The optimized Ag/hZrO 2 /CN catalyst demonstrated substantial photocatalytic performance, achieving 97.6 % degradation of methylene blue (MB) and 99.5 % degradation of thiram (TRM) within 90 min under simulated sunlight using a 500 W Xe lamp. The improved property is likely attributed to the synergistic effect among three constituents and the effective segregation of photogenerated electron-hole pairs in ZrO 2 , g-C 3 N 4 and Ag NPs, as confirmed by photocurrent and EIS analysis. Based on free radical scavenging studies (e − , h + , OH and O 2 − ), the mechanism underlying the boosted photocatalytic activity was suggested. Moreover, Ag/hZrO 2 /CN presented excellent surface enhanced Raman scattering activity, achieving quantitative sensing of MB and TRM with limits of detection of 5 × 10 −8 and 10 −6 mol/L, respectively, and a favorable linear correlation between SERS intensities and logarithmic concentration (R 2  ≥ 0.97). Additionally, Ag/hZrO 2 /CN accomplished recyclable SERS detection of MB and TRM through stimulated sunlight irradiation, which is significant for the recyclable SERS detecting through fast sunlight-powered procedure.