Enhanced photocatalytic H2 generation on noble metal modified TiO2 catalysts excited with visible light irradiation

Abstract

Photocatalysts were prepared by the deposition of noble metal nanoparticles (Au, Pt, Rh or Ru) on different commercially available titanias. The photocatalytic performance of these catalysts was studied for the evolution of H 2 during excitation with visible light. Experiments were carried out in irradiated suspensions containing various organic compounds. Noble metal nanoparticles can promote the lowering of the overvoltage of H ? reduction. The noble metal nanoparticles were deposited onto the TiO 2 surface by in situ chemical reduction in a quantity of 1 wt%. Three aspects were considered: (i) the photocatalytic performance of different bare TiO 2 deposited with Pt; (ii) the effect of the deposition of Au, Pt, Rh or Ru nanoparticles onto the TiO 2 surface; and (iii) choosing the most suitable H 2 production supporting organic compound. The rate of H 2 evolution proved to be strongly dependent on the quality of TiO 2 powder and the presence of different organics. The applied noble metal was also an efficiency determining factor during these photocatalytic reactions. With the best combination of the above mentioned circumstances, we achieved promising results to be able to effectively harvest the energy of sunlight.

Associating low crystallinity with peroxo groups for enhanced visible light active photocatalysts

“…There are numerous instances in the literature that by applying different approaches (e.g. doping, deposition of noble metals) successful enhancement of visible light excitability was observed which corresponded well with the resulting photocatalytic efficiency [12,14,34,45]. Presumably, the greatly enhanced visible light excitability of pH3_55 and pH3_70 peroxo-titania will be beneficial for the photocatalytic efficiency.…”

Visible-Light-Active TiO2-Based Hybrid Nanocatalysts for Environmental Applications

“…Several other factors may also affect photocatalytic efficiency, e.g., the surface properties, the particle size of the catalysts their morphology, and the composition and organization of the metal and TiO 2 [68]. Therefore, great efforts have been devoted to the synthesis of well-controlled and highly efficient plasmonic metal-TiO 2 nanostructures [16,18,37].…”

“…For instance, 5.7 nm Au nanoparticles have been deposited on the surface of TiO 2 P25 Aeroxide from Evonik (formerly known as TiO 2 P25 Degussa) by in situ chemical reduction in water. Trisodium citrate has been utilized to control and stabilize the growth of Au nanoparticles and to attain a nearly monodisperse size distribution, whereas NaBH 4 has been selected as the reducing agent [68]. Au nanoparticles can be grown onto semiconductor structures by a deposition-precipitation procedure, followed by calcination, as reported by Silva and co-workers [81].…”

Utilization of Carbon Nanospheres in Photocatalyst Production: From Composites to Highly Active Hollow Structures

“…Over the last three decades, a large number of publications were dedicated to the improvement of the photocatalytic activity and the excitability of TiO 2 . These included doping with various non-metals [2,6,10,14], modifying with noble metals [15,16,17], sensitizing with dyes [18,19], synthesizing TiO 2 with various morphologies [11,20], and coupling TiO 2 with other semiconductors [21,22,23]. A promising direction is the use of different forms of carbon, e.g., carbon nanotubes [2,24,25,26], graphite oxide [27], activated carbon [7], graphene [28], and graphene oxide [1].…”