Photocatalytic behavior of metal-decorated TiO2 and their catalytic activity for transformation of glycerol to value added compounds

Photoinduced Glycerol Oxidation over Plasmonic Au and AuM (M = Pt, Pd and Bi) Nanoparticle-Decorated TiO2 Photocatalysts

“…The principle product was GCD in the presence of all the evaluated photocatalysts except for Au 3 Bi 3 /TiO 2 , where GCAD was the principle product. As reported previously [ 53 ], monometallic Bi NPs decorated on TiO 2 did not promote the formation of GCAD as a major product. Accordingly, it is suggested that the synergism between the bimetallic Au–Bi was a vital factor in the formation of GCAD from glycerol.…”

“…Moreover, the decorated Bi NPs cannot extract the excited e − from the Au or supported TiO 2 due to its lower work function (4.22 eV) than that of Au (5.1 eV) and TiO 2 (4.9 eV), resulting in unalleviated e − - h + recombination ( Figure 14 a). The high photocatalytic activity of the Au 3 Bi 3 /TiO 2 compared to the parent TiO 2 was due to the presence of the valence band tail above the valence band, which was caused by the hybridization of the Bi 6s and O 2p orbital, and the existence of the Ti 3+ state below the conduction band [ 53 ], which allowed an easy jump of photogenerated e − from either the valence band tail level to either a shallow trap (Ti 3+ state) or conduction band. In addition, as previously mentioned, the Bi6s is widely dispersed in the hybrid orbital of Bi6s-O2p leading to an increased charge mobility and consequently an improved photocatalytic activity of the parent photocatalyst [ 78 ].…”

“…The Pt/TiO 2 photocatalyst exhibited a more efficient reaction rate for glycerol oxidation than bare TiO 2 , which was mainly due to the increased separation of the charge carriers and the elevation of the rate-limiting cathodic half reaction (oxygen (O 2 ) reduction) in the glycerol photo-oxidation. Likewise, the addition of any of Bi, Au, Pt or Pd on TiO 2 was reported in our previous work to further enhance the rate of glycerol photo-oxidation, where Au-decorated TiO 2 exhibited the best performance [ 53 ]. However, the photocatalytic conversion of glycerol over the surface of metals and metal oxides to the desired products still requires a thorough comprehension of the surface chemistry and reaction mechanism.…”

“…The aim was to explore the individual as well as the combined effects of Au, Au-Bi, Au-Pt and Au-Pd on the photocatalytic performance of TiO 2 for the photocatalytic oxidation of glycerol. The Bi, Pt and Pd NPs were selected to combine with Au because Bi prefers to react with the secondary hydroxyl group of glycerol to form DHA while the Pt and Pd can promote the activity of glycerol oxidation [ 53 , 54 , 55 , 56 ].…”

Supported Plasmonic Nanocatalysts for Hydrogen Production by Wet and Dry Photoreforming of Biomass and Biogas Derived Compounds: Recent Progress and Future Perspectives

“…Due to a higher energy band gap between the conduction band of TiO 2 and a Pd plasmon metallic state than in the case of Pt, the recombination in Pd/TiO 2 system occurs more rapidly than in the Pt/TiO 2 . In the Au/TiO 2 system the recombination events are mitigated, because the in the Au‐related metallic state the energy level is lower in comparison to the conduction band of TiO 2 , what may be related to higher participation of photogenerated electrons in the transformation [108] . Some examples of experiment of glycerol PR over a 0.5 % Pd/TiO 2 and for 2 % Au/TiO 2 were proposed in [109].…”