Spray-dried microporous Pt/TiO2 degrades 4-chlorophenol active under UV and visible light

Abstract We prepared nanoparticles of a microporous Pt catalyst over TiO 2 (Pt x T, x= 0.2–0.8 wt. %) with exposed (001) facets by sol-gel followed by spray-drying of a Ti(oBu) 4 -C 2 H 6 O and H 2 PtCl 6 -H 2 O mixture. The characterization methods were XRD, FTIR, BET, SEM-EDX/TEM, UV-DRS, Photoluminescence (PL) and Raman spectroscopy. XRD analysis confirmed that all samples consisted of mainly anatase with little rutile, while pure TiO 2 (T) consisted of only anatase after calcination at 550° C. The deposition of Pt x on TiO 2 produces tensile strain for x x -TiO 2 shifted to greater values compared to control T (UV–vis DRS spectroscopy). The Pt x T powders exhibited lower PL intensity than T, since the addition of Pt nanoparticles up to 0.8% captures the photogenerated electrons. The broadening of the Raman peak and the small frequency shift for the Raman bands (1-E g and B 1g ) indicate that there are oxygen vacancies and crystal lattice distortions. The degradation of 4-chlorophenol under UV and visible light was the model reaction for the photocatalytic activity. Radical scavenging experiments demonstrated that superoxide (O 2 − ) anions followed by photogenerated h + species are mainly responsible for the degradation of 4-chlorophenol. The Pt x T samples degrade up to 40% more 4-chlorophenol under UV and Vis irradiation than Degussa P25 and T as a consequence of the high crystallinity, homogenous distribution of Pt, as well as surface area >300 m 2 /g and spherical morphology. Based on the data, we propose a photocatalytic mechanism.