| Summary: | In this study, a reversed photodeposition method was developed to minimise the use of noble metals (NM) as doping agents for photocatalytic enhancement, addressing the high cost associated with commercialisation. Unlike the conventional approach where NM is doped onto titanium dioxide (TiO2) before immobilisation, this method involves doping NM on the surface of immobilised TiO2. The immobilisation was achieved through a dip-coating method using a coating solution containing Degussa P-25 TiO2, epoxidised natural rubber (ENR-50) and polyvinyl chloride (PVC) as the polymer binder. This study focused on doping silver (Ag) on TiO2/ENR/PVC to form ATEP plates. Doping was carried out at different concentrations (100-500 ppm) using both reversed (R) and normal (N) approaches, with photodeposition times ranging from 1 to 6 hours. The photocatalytic performance of the immobilised ATEP(R) and ATEP(N) was determined through the photodegradation of 12 mg L-1 methylene blue (MB) dye. X-ray diffraction (XRD) analysis revealed that the etching of ENR/PVC in the reversed method exposed more TiO2 crystals. Field emission scanning electron microscopy (FESEM) images also proved that the polymer etching resulted in a more porous TiO2 structure in the reversed method. Energy-dispersive X-ray spectroscopy (EDX) confirmed that the reversed method achieved a higher weight percentage of Ag, which enhanced the surface plasmonic resonance (SPR) effect and improved photocatalytic performance. The optimal sample, 300-ATEP(R 5h), exhibited a higher rate constant (k = 0.0495 min-1) than the 400-ATEP(N) (k = 0.0463 min-1) sample over 60 minutes of MB dye degradation. This was due to the more porous TiO2 structure and the stronger SPR effect of Ag in the reversed sample. The Ag concentration was effectively reduced by half while achieving greater photocatalytic performance in 300-ATEP(R 5h) than in 400-ATEP(N). The photocatalytic performance of the samples produced using the reversed method surpassed that of the normal method, with the optimal sample maintaining stability over six cycles. © 2024, Malaysian Society of Analytical Sciences. All rights reserved.
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