Visible lightinduced hydrogen production from glycerol aqueous solution on hybrid Pt–CdS–TiO2 photocatalysts

Abstract

Binary (Pt/hexCdS) and ternary (Pt/CdS/TiO2 and Pt/TiO2/hexCdS) hybrid photocatalysts were evaluated in photoinduced reforming of glycerol under visible light irradiation ( > 418 nm). The resulting hybrid materials are photocatalytically efficient with respect to hydrogen gas production. The relative order of reactivity for the synthesized hybrid catalysts was found to be: Pt/hexCdS > Pt/CdS/TiO2 > Pt/TiO2/hexCdS. The systems with CdS/aqueous solution interfacial contact showed higher activity, suggesting that the hydrogen production mechanism can be strongly influenced by hydrolytic surface reactions on CdS. The potential gradient created at the CdS/TiO2 or TiO2/hexCdS interface may also play an important role in the photoelectrochemical mechanism. Therefore, carbonyl compounds such as acrolein and propanone, identified in the liquid phase after 7 h of irradiation, lead us to propose the first steps of a photoelectrochemical mechanism in the photoinduced reforming of glycerol.