Abstract
Immobilized TiO 2 -based photocatalysts are promising for CO 2 photoreduction because they combine chemical stability, mechanical robustness, and potential compatibility with continuous-flow systems. In this work, TiO 2 nanostructures were synthesized directly on titanium mesh by alkaline hydrothermal treatment. The effects of NaOH concentration, Pt photodeposition, and nitrogen doping on morphology, structure, optical properties, and CO 2 photoreduction performance were investigated. SEM analysis showed that dense nanosheet TiO 2 layers were formed on the Ti mesh surface. Increasing the NaOH concentration from 2 to 3 M enhanced nanostructure growth and increased the oxide layer thickness from approximately 4.3–6.1 μm, although local structural damage appeared at higher alkalinity. XRD confirmed the formation of crystalline anatase TiO 2 , while EDS verified Pt deposition and nitrogen incorporation. UV-Vis analysis showed strong UV absorption and slight narrowing of the apparent optical band gap for modified photocatalysts. Photocatalytic CO 2 reduction under UV irradiation produced CH 4 and CO as main products. Pt/TiO 2 /Ti exhibited the best performance, achieving a CH 4 formation rate of 40.59 μmol·g −1 ·h −1 and 99.5% electron selectivity after 11 h. Nitrogen doping enhanced total carbon-product formation but favored CO generation. These results demonstrate that Pt-functionalized TiO 2 /Ti mesh is an efficient immobilized photocatalyst for selective CO 2 -to-CH 4 photoreduction.