Photothermal catalytic properties of TiO2+Pt solids: A multifunctional approach to environmental remediation

This study addresses a gap in the literature on the multipurpose capabilities of TiO 2 +Pt materials by investigating their multifunctional catalytic applications. Here, for the first time, the same synthesized TiO 2 +Pt catalysts are used as photocatalysts for the oxidation of bisphenol A (BPA) in water and as thermal and photothermal catalysts for the H 2 -assisted reduction of NO 2 . For this purpose, a series of anatase TiO 2 support (TP) and Pt catalysts (TP+Pt) with Pt loadings of 0.5, 1 and 2 wt.% were synthesized and characterized using different characterization techniques to determine their morphological, optical and electronic properties. The results confirmed that the wet impregnation technique used allowed a uniform dispersion of Pt on the TiO 2 surface without altering the crystalline structure of TiO 2 and that the average size of the Pt particles (1-1.5 nm) was not significantly affected by the amount of Pt added. The localized surface plasmon resonance (LSPR) effect of Pt enabled the TP+Pt solids to be catalytically active when illuminated with visible light. The photoluminescence measurements showed that the electron-hole recombination rate decreased and the lifetime of the charge carriers increased with increasing Pt content in the TP+Pt catalysts. XPS analysis revealed that the Pt modification facilitated the formation of Ti 3+ sites and improved the adsorption of oxygen species, which are crucial for photocatalytic reactions. Furthermore, the Schottky barrier height (SBH) decreased with increasing Pt content in the samples. The TP + 2% Pt catalyst showed the highest BPA degradation rate, which can be attributed to the increased formation of reactive oxygen species such as superoxide anion radicals ( • O 2 - ) and hydroxyl radicals ( • OH). The SBH value played an important role in optimizing the photocatalytic performance of TP+Pt samples, where a low SBH value favoured reduction reactions as it enabled faster electron transfer from Pt to TiO 2 , while higher SBH values were beneficial for oxidation reactions as they prevented the re-injection of electrons from TiO 2 to Pt. In experiments on NO 2 reduction, the TP+Pt catalysts showed a significantly higher thermal catalytic activity compared to bare TiO 2 , which increased with increasing Pt content. The introduction of photocatalysis further improved the performance of the TP+Pt catalysts and led to high NO 2 reduction rates and N 2 selectivity even at 30 °C. The results emphasize the central role of SBH in tuning photocatalytic performance of TP+Pt catalysts. By utilizing adjustable SBH values, these materials show remarkable potential for various environmental applications, including photocatalytic degradation of pollutants dissolved in water and photothermal reduction processes for air purification. • The Pt dispersion on the TiO 2 surface was uniform, with a Pt particle size of 1-1.5 nm. • Pt loading increased electron lifetime and reduced recombination, boosting activity. • TiO 2 +Pt catalysts showed improved BPA oxidation and NO 2 reduction under visible light. • Tuning the height of the Schottky barrier improved oxidation and reduction efficiency. • TiO 2 +Pt solids show potential for remediation as efficient photo/thermal catalysts.