Structure Sensitivity of Nano-structured CdS/SBA-15 Containing Au and Pt Co-catalysts for the Photocatalytic Splitting of Water

Abstract

Photocatalysts containing nanocrystallites of cadmium sulphide dispersed in the channels of mesoporous silicate SBA-15 exhibited enhanced activity for visiblelight mediated splitting of water, as compared to bulk CdS. Whereas the incorporation of 1 wt.% Pt co-catalyst in CdS/ SBA-15 led to a substantial increase in H 2 yield, Au at similar loading resulted in marginally decreased activity.The results indicate that the photocatalytic activity of CdS crystallites is structure sensitive. Similarly, the role of a noble metal may be associated with the particle size dependent micro-structural features, rather than its electronic properties such as the work function or the heat of adsorption of reactant or product molecules.Keywords Nano-structured cadmium sulphide Á Photocatalysis Á Structure sensitivity Á Splitting of water Á Role of noble metal co-catalyst

Mesoporous TiO2/SBA-15, and Cu/TiO2/SBA-15 Composite Photocatalysts for Photoreduction of CO2 to Methanol

“…It was found that the highly dispersed TiO 2 catalyst anchored on porous Vycor glass exhibited high and characteristic photocatalytic reactivity, when compared to bulk TiO 2 powder [9]. Lunawat et al [10] reported that CdS nanocrystallites dispersed in the channels of mesoporous silicate SBA-15 exhibited a much higher hydrogen evolution rate from photocatalytic water splitting than bulk CdS. Compared to microporous material, mesoporous material has a relatively high specific surface area, a mechanical property and its uniform pore sizes are adjustable for a wide range.…”

Cd1−xZnxS solid solutions supported on ordered mesoporous silica (SBA-15): Structural features and photocatalytic activity under visible light

“…Similarly, it was reported that CdS/SBA-15 photocatalyst maintained a significantly long active life during visible lightdriven hydrogen production from water splitting [24].…”

“…One of the most interesting way to control these parameters is the synthesis of semiconductor nanostructures such as nanowires, nanobelts, nanotubes, nanorods, and nanocluster dispersed in solutions [22,23] or deposited on mesoporous silica substrates such SBA-15 [24] or Zn-doped SBA-15 [25] in order to ensure easier catalyst recovery after completion of the reaction and at the same time to provide a hydrophobic environment to catalyst particles [24].…”

“…Regarding new support materials, mesoporous molecular sieves such as SBA-15 are promising candidate because of their uniform porous structure, high specific area (600e100 m 2 /g), hexagonal array of uniform tubular channels with pore diameters ranging from 5.0 to 30.0 nm and high hydrothermal stability during long term water splitting reaction under visible light irradiation [24]. In these supported systems, semiconductor nanoparticles may exhibit quantum confinement effect when their dimensions are reduced to the size of the Bohr radius of bulk excitation.…”

“…This quantum confinement effect leads to a drastic change in the electronic structure and physicochemical properties of the semiconductor photocatalysts [23]. Recently, study by Lunawat et al [24] demonstrated that photocatalysts containing nanocrystallites of cadmium sulphide dispersed in the channels of mesoporous silicate SBA-15 exhibited enhanced activity for visible light-mediated splitting of water, as compared to bulk CdS. Zn-doped SBA-15 mesoporous silica was found also to be a good support for CdS photocatalysts because of its particle sieving ability to immobilize the sizequantized CdS nanoparticles selectively and to archive a well-defined nanostructure [25].…”