Location and State of Pt in Platinized CdS/TiO₂ Photocatalysts for Hydrogen Production from Water under Visible Light

Abstract

CdS/TiO 2 composite photocatalysts were platinized by different methods such as photodeposition (PD), wet impregnation (WI), and chemical reduction (CR), and studied for hydrogen production from water under visible light. All Pt species were in the metallic state, yet PD and WI photocatalysts contained electrondeficient Pt. In particular, Pt-Ti formation was identified in the WI catalyst, which contributed to electron deficiency of Pt. These two photocatalysts of electron-deficient Pt exhibited higher rates of hydrogen evolution due to favorable diffusion of photoelectrons from excited CdS toward the Pt. Between PD and WI photocatalysts, the PD catalyst showed a lower rate because part of the Pt in the catalyst resided on CdS, whereas all Pt species were located on TiO 2 nanoparticles for WI and CR catalysts. The results indicate that the location as well as the electronic state of Pt is important for the high performance of platinized CdS/TiO 2 photocatalysts in hydrogen production from water.

Hydrogen Production over Titania‐Based Photocatalysts

“…A noble metal with a larger work function results in a stronger Schottky barrier effect, and therefore shows a better activity for hydrogen evolution. [45,47] This is another reason why Pt-loaded TiO 2 always shows the highest activity.…”

“…[44] Among all these metals, Pt is the most widely used because it has the lowest overpotential and commonly shows the highest activity for hydrogen generation. [45][46][47] Except for noble metals, NiO [48] and RuO 2 [49] have also been used to decrease the overpotential for hydrogen and oxygen evolution, respectively.…”

Fabrication of iron-cerium mixed oxide: an efficient photocatalyst for dye degradation

“…The mixed oxides systems have the ability to obtain structures in combinations with the properties that neither individual oxide possesses. Coupling of two semiconductors (e.g., CdS/TiO 2 , CdS/ZnO, TiO 2 /SnO 2 , CdSe/TiO 2 ) with suitable energetics can significantly improve the selectivity and enhance the charge separation yield (Jang et al, 2008;Shvalagin et al, 2007;Liu et al, 2007;Kim et al, 2009). The combination of ceria with Fe 2 O 3 would be an efficient photocatalyst and will fullfil the seeking property of individual material.…”

Ternary CdS/Au/3DOM-SrTiO 3 composites with synergistic enhancement for hydrogen production from visible-light photocatalytic water splitting

“…Moreover, the surface plasmon resonance (SPR) of metal nanoparticles arising from the collective oscillation of electrons in the metallic nanostructure could also improve the performance of photocatalysts through hot electron transfer [25][26][27][28][29][30][31] . Many researchers had attempted to fabricate the ternary composites using two semiconductors and one noble metal, such as Au/CdS/TiO2 [23,[32][33][34][35][36][37] , Au/CdS/WO3 [38,39] , Pt/CdS/TiO2 [40][41][42][43][44][45] , and Au/CdS/ZnO [46][47][48] . However, improving the light harvesting efficiency through a special nanostructure design is still an attractive research field.…”