Non-oxide Semiconductors Mixed with Metals or Metal Oxides

1 Non-oxide Semiconductors Mixed with Metals or Metal Oxides [34 41,149-156] 

The limiting factors that control photocatalysis efficiency are rapid recombination between photo-generated charge carriers, and the backward reaction leading to recombination of the formed molecular hydrogen and oxygen. To retard these processes efforts have typically focused on surface modification of the semiconductor particles using metals or metal oxides. 

Photoplatinization of CdS particles has been found effective in limiting the susceptibility of CdS to photocorrosion [36-39]. Both Reber et al. [38,149] and Matsumara et al. [150] used platinum metal loaded CdS particles, in the presence of sulfite and sulfide ions, for hydrogen production the amount of metal loading, electrolyte concentration and pH affect the rate of hydrogen production. In sulfide ion containing solutions, the highest hydrogen production rate is obtained near pH = 12.8, while in sulfite ion 

Metal oxide, e.g. RUO2 [35,36] and WO3 [151], loaded Cd8 colloidal suspensions with and without Ft functionalization were investigated for water decomposition under visible light. WO3-Pt/Cd8, in an aqueous solution of methyl viologen (MV ) which serves as an electron relay, has been found most efficient to date in terms of water splitting, see reactions (7.4.1) to (7.4.8) [151]  

The conduction band electrons of Cd8 move to Ft that in turns reduces MV. The reduced methyl viologen in turn reduces a hydrogen ion to a hydrogen molecule. The valence band boles of WO3 then oxidize water to O2 molecules. 

---