Influence of Excitation Wavelength (UV or Visible Light) on the Photocatalytic Activity of Titania Containing Gold Nanoparticles for the Generation of Hydrogen or Oxygen from Water

Abstract

Gold nanoparticles supported on P25 titania (Au/TiO(2)) exhibit photocatalytic activity for UV and visible light (532 nm laser or polychromatic light λ > 400 nm) water splitting. The efficiency and operating mechanism are different depending on whether excitation occurs on the titania semiconductor (gold acting as electron buffer and site for gas generation) or on the surface plasmon band of gold (photoinjection of electrons from gold onto the titania conduction band and less oxidizing electron hole potential of about -1.14 V). For the novel visible light photoactivity of Au/TiO(2), it has been determined that gold loading, particle size and calcination temperature play a role in the photocatalytic activity, the most active material (Φ(H2) = 7.5% and Φ(O2) = 5.0% at 560 nm) being the catalyst containing 0.2 wt % gold with 1.87 nm average particle size and calcined at 200 °C.

Synthesis and Characterization of Au@TiO₂ NWs and their Catalytic Activity by Water Splitting: A Comparative Study with Degussa P25

“…550 nm was observed for the 10%Au@TiO 2 NWs. This shoulder was unambiguously attributed to the surface plasmon resonance (SPR) exhibited by the Au NPs (Tanaka et al, 2012;Fang et al, 2012;Chen et al, 2011;Gomes-Silva et al, 2011). The plasmon absorption depends on the size of the gold nanoparticles and arises from the collective oscillations of the free conduction band electrons that are induced by the incident electromagnetic radiation on Au NPs (Fang et al, 2012;Chen et al, 2011;Gomes-Silva et al, 2011).…”

“…By reducing the photogenerated charge carriers, the UV activity is increased due to the electron transfer from the Conduction Band (CB) of TiO 2 to the noble metal nanoparticles (Chen et al, 2011). The photoactivity in the visible range of the electromagnetic spectrum can be explained due to the surface plasmon resonance effect and charge separation by the transfer of photoexcited electrons from the metal nanoparticles to the CB of TiO 2 (Jose et al, 2013;Naldoni et al, 2013;Chen et al, 2011;Gomes-Silva et al, 2011;Murdoch et al, 2011;Baatz et al, 2008;Oros-Ruiz et al, 2013).…”

“…Among noble metals, gold has gained much attention since the 80's because of its wide range of applications, including electronics, photodynamic therapy, delivery of therapeutic agents, sensors, probes, diagnostics and catalysis (Primo et al, 2011;Ortega et al, 2014;Yuzawa et al, 2012;Tanaka et al, 2012;Padikkaparambil et al, 2013;Fang et al, 2012;Naseri et al, 2011;Gomes-Silva et al, 2011). Different approaches have been developed in order to incorporate gold Nanoparticles (Au NPs) on the surface of TiO 2 .…”

Facet‐Engineered Surface and Interface Design of Photocatalytic Materials

“…Based on this correlation, we have designed a Ag‐BiOCl‐Pd hybrid structure for synergizing the interfacial charge transfer of plasmonic metal‐semiconductor (Ag‐BiOCl) with semiconductor‐metal (BiOCl‐Pd) Schottky junctions 22. In a plasmonic metal‐semiconductor interface, the injection of plamsonic hot carriers to semiconductor follows an opposite direction to the charge trapping by metal through the Schottky junction 123, 124. In our design, two different metal‐semiconductor interfaces were established to circumvent this undesired situation, in which the semiconductor facets and metals were rationally selected for the plasmonic effect and Schottky junction, respectively.…”

Propagating Surface Plasmon Polaritons: Towards Applications for Remote‐Excitation Surface Catalytic Reactions

“…In addition, due to the high throughput and low energy requirements, a novel application of plasmonics in chemical reactions gains significant attention, as reported in works on dissociation of hydrogen15, 16 and water,17, 18 photochemical19, 20, 21, 22, 23 and plasmon‐driven chemical reactions,24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 etc. SPs excited on the surface of gold or silver can non‐radiatively decay into so‐called hot electrons with a high energy between the Fermi and vacuum energy level 36, 37, 38, 39, 40.…”