Au/TiO2(P25)-gC3N4 composites with low gC3N4 content enhance TiO2 sensitization for remarkable H2 production from water under visible-light irradiation

Abstract

A series of ternary Au/TiO 2 (P25)-gC 3 N 4 heterostructure photocatalysts with low Au nanoparticle (NP) loading and gC 3 N 4 content were synthesized and evaluated for H 2 production from water with a very low amount of sacrificial agent (1 vol%) under solar and visible-light irradiation. The optimized composite, 0.3 wt% Au/ TiO 2 (P25)-gC 3 N 4 (95-5), exhibited a remarkable production rate under visible light (419 μmol À 1 h À 1 g catalyst of H 2 ), corresponding to almost twice the cumulated H 2 production over 2.5 h as that of the Au/TiO 2 (P25) reference. To best of our knowledge, this high of a yield has never been reported for comparable experimental conditions. The highest performing composite was characterized using UV-vis, XPS, UPS, BET, TEM, and TRMC techniques. The performance of the photocatalyst could be correlated to contributions of various phenomena such as effective heterojunction formation of TiO 2 with gC 3 N 4 operating in a Z-scheme dynamic allowing TiO 2 photosensitization towards visible-light, also leading to new electronic hybrid states, and plasmonic Au/support Schottky junction allowing electronic trapping sites and co-catalytic effects. These contributions resulted in more efficient light harvesting and separation of the charge carriers to enhance visible light driven activity.

The biopolymer-assisted synthesis of assembled g-C3N4 open frameworks with electron delocalization channels for prompt H2 production

“…To overcome these disadvantages, several modification treatments have been developed and investigated, including constructing junctions, 9–12 doping with hetero- or homo-atoms 13–15 and controlling various microstructures. 16–18 Among these developed methods, controlling microstructures have attracted considerable research interest.…”

Highly Promoted Photocatalytic Hydrogen Generation by Multiple Electron Transfer Pathways

“…In addition, introducing cocatalysts in conjugated-titania heterostructures can remarkably enhance the photocatalytic efficiency due to the prolonged life time of the charge carriers and increased active sites. Although some conjugated polymer-semiconductor-based ternary structure nanocomposites have successfully constructed such as Pt@TiO2/g-C3N4 [19], CdS/Cu7S4/g-C3N4 [20], Au/TiO2(P25)-gC3N4 [21], little attention has been paid to considering the multiple electron transfer pathways. Indeed, the multiple electron-transfer pathways are very important for the charge carrier separation and hot electron transfer and accumulation by manipulating deposition cocatalysts on different catalysts in a ternary system [22].…”

Urea-induced supramolecular self-assembly strategy to synthesize wrinkled porous carbon nitride nanosheets for highly-efficient visible-light photocatalytic degradation

“…5 However, the photocatalytic efficiency of bulk g-C 3 N 4 obtained by thermal polymerization of traditional precursors such as melamine, dicyandiamide and cyanamide is restricted by rapid recombination of photogenerated electron-hole pairs, marginal visible light absorption and small specic surface area. 6,7 In order to improve its photocatalytic performance, various methods have been developed, such as semiconductor coupling, 8,9 element doping [10][11][12] and nanostructure engineering. 13,14 To date, tremendous efforts have been devoted to design nanostructures of g-C 3 N 4 because the photocatalytic performance of g-C 3 N 4 depends strongly on its morphology.…”