Understanding the superior photocatalytic activity of noble metals modified titania under UV and visible light irradiation

Abstract

Although TiO2 is one of the most efficient photocatalysts, with the highest stability and the lowest cost, there are drawbacks that hinder its practical applications like its wide band gap and high recombination rate of the charge carriers. Consequently, many efforts were directed toward enhancing the photocatalytic activity of TiO2 and extending its response to the visible region. To head off these attempts, modification of TiO2 with noble metal nanoparticles (NMNPs) received considerable attention due to their role in accelerating the transfer of photoexcited electrons from TiO2 and also due to the surface plasmon resonance which induces the photocatalytic activity of TiO2 under visible light irradiation. This insightful perspective is devoted to the vital role of TiO2 photocatalysis and its drawbacks that urged researchers to find solutions such as modification with NMNPs. In a coherent context, we discussed here the characteristics which qualify NMNPs to possess a great enhancement effect for TiO2 photocatalysis. Also we tried to understand the reasons behind this effect by means of photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra, and Density Functional Theory (DFT) calculations. Then the mechanism of action of NMNPs upon deposition on TiO2 is presented. Finally we introduced a survey of the behaviour of these noble metal NPs on TiO2 based on the particle size and the loading amount.

Effect of reducible oxide–metal cluster charge transfer on the structure and reactivity of adsorbed Au and Pt atoms and clusters on anatase TiO2

“…Noble metal nanoparticles (NPs) supported on oxide surfaces are widely used in heterogeneous catalysis [1][2][3][4][5][6][7][8][9] and photocatalysis, where they can effectively inhibit the recombination of photogenerated electron-hole pairs in photocatalytic processes, 10,11 and at the same time facilitate/enhance the catalytic activity. 11,12 Among oxide supports for metal NPs, titanium dioxide (TiO 2 ) is known for showing significant promoting effects of the NPs' catalytic activity.…”

“…11,12 Among oxide supports for metal NPs, titanium dioxide (TiO 2 ) is known for showing significant promoting effects of the NPs' catalytic activity. [13][14][15][16][17][18][19][20][21][22][23] In particular, many studies have focused on TiO 2 -supported Au and Pt clusters and NPs as promising catalysts for various reactions, ranging from low-temperature CO oxidation to photocatalytic water splitting.…”

Metal oxide semiconducting interfacial layers for photovoltaic and photocatalytic applications

“…Among the various structures thus produced with this combination, Au/TiO 2 nanostructures show promising prospect, as the surface plasmon resonance (SPR) effect in these structures enhances the photoactivity of titania under visible light. In this process, the photogenerated electrons possess negative potential higher than that of the conduction band of the TiO 2 ; thereby, the photogenerated electrons transfer efficiently from excited Au NPs to TiO 2 NPs [189][190][191]. For instance, in the event of degradation of the pollutant 4-chlorophenol (4CP) using P-25 titania (commercial TiO 2 ), the Au NPs significantly enhanced the catalytic activity by 80 % [192].…”

“…Employing plasmonic technology for energy conversion is found to be a promising alternative to the conventional electron-hole separation in semiconductor devices. This technique involves generation of hot electrons in plasmonic nanostructures by means of electromagnetic decay of surface plasmons [187][188][189][190]. The working principle of the plasmonic energy conversion at the semiconductor interface is depicted in Fig.…”

Ag@Ag2SO4 nanoparticles: simple microwave-assistance synthesis, characterization and its co-photocatalytic degradation of methylene blue

“…Till now, various materials have been used as semiconductor photocatalysts and among of them, TiO 2 is an appropriate and efficient choice to use owing to its wellknown incomparable qualities [7][8][9][10][11]. Nevertheless, this semiconductor has a few major drawbacks on its photoexcitation domain includes: (1) wide band gap energy 3.2 eV, (2) possess low absorption capability especially in the visible light region and (3) exhibit high recombination of photogenerated electron-hole thus hindering its visible light-driven photocatalytic performance [1,[12][13][14][15][16][17][18][19]. Thus, remarkable efforts have been devoted to overcome all these limitations by doping/composite with metal, non-metal (NPs), noble metal inclusion or deposition to gain plasmonic property [20][21][22][23][24][25][26][27][28] and etc.…”