MnOx and Pd Surface Functionalization of TiO2 Thin Films via Photodeposition UV Dose Control

This study investigated the influence of the ultraviolet (UV) dose ( D U V ) on the photodeposition of MnOx and Pd cocatalysts on 300-nm-thick anatase TiO2 thin films, which were prepared via sol-gel dip-coating on a glass substrate. MnOx and Pd were photodeposited using increasing UV doses ranging from 5 to 20 J cm(-2), from 5 mM aqueous electrolytes based on Mn2+/IO3- or Pd2+, respectively. The effect of the D U V on the MnOx photodeposition resulted in an increase in Mn2+ surface content, from 2.7 to 5.2 at.%, as determined using X-ray photoelectron spectroscopy (XPS). For Pd, increasing the UV dose led to a reduction in the oxidation state, transitioning from Pd2+ to Pd-0, while the overall Pd surface content range remained relatively steady at 2.2-2.4 at.%. Both MnOx/TiO2 and Pd/TiO2 exhibited proportional enhancements in photocatalytic activity towards the degradation of methylene blue. Notably, Pd/TiO2 demonstrated a significant improvement in photocatalytic performance, surpassing that of pristine TiO2. In contrast, TiO2 samples functionalized through wet impregnation and thermal treatment in the same electrolytes showed overall lower photocatalytic activity compared to those functionalized via photodeposition.