Abstract
Abstract: Protonated titanate nanotubes (HTiNts) were synthesized using the hydrothermal method, followed by proton exchange with acid. Gold nanoparticles decorated titanate nanotubes (AuHTiNts) were obtained by the reduction of AuCl4- under vigorous stirring with an aqueous solution of HTiNts containing 1 wt% of ascorbic acid. To investigate the surface structural chemistry of the titanate and AuHTiNts, the following characterization methods were used: scanning and transmission electron microscopy, X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, Raman spectroscopy and X-ray photo-electron spectroscopy. The mean internal and external diameters for titanate nanotubes were found to be 5.46 ± 0.08 nm and 8.42 ± 0.03 nm, respectively, whereas the mean diameter of gold nanoparticles was measured to be 9.68 nm ± 0.03 nm. The as-synthesized AuHTiNts was used as photocatalyst in hydrogen production from glycerol as a sacrificial agent. The enhancement in the production of hydrogen, using the heterogeneous AuHTiNts catalysts, can be attributed to the intrinsic catalytic potential of gold as well as its interactions with titanate nanostructure.
Highlights
After Fujishima and Honda (1972) reported the water oxidation with TiO2 as the photo-catalyst for the first time in 1972, generating hydrogen and oxygen, many studies have been developed with different electrolytes (De la Piscina and Homs 2008) and photoelectrodes (Valdes et al 2012) to increase the hydrogen production (Ahmad et al 2015)
Many studies has been focused on the synthesis of suitable hetero-nanostructures based on TiNT and TiO2 nanotubes as substrates which can be decorated with different active catalysts leading to photocatalytic applications (Kukovecz et al 2016, Yang et al 2015)
By AuNPs decoration, we have been able to overcome the problem of large band gap of Titanate nanotubes (TiNts), a central issue that restricts the optical response in only UV range and thereby lowers the photocatalytic performance of these semiconductors and had been able to extend the application of this material in the wider visible range
Summary
After Fujishima and Honda (1972) reported the water oxidation with TiO2 as the photo-catalyst for the first time in 1972, generating hydrogen and oxygen, many studies have been developed with different electrolytes (De la Piscina and Homs 2008) and photoelectrodes (Valdes et al 2012) to increase the hydrogen production (Ahmad et al 2015). The usage of TiNts, as well as TiO2 as efficient photocatyst is limited due to their high band gap (3.4 eV) which restricts their capability to capture light beyond the UV region (Liu et al 2014) To overcome this barrier, many studies has been focused on the synthesis of suitable hetero-nanostructures based on TiNT and TiO2 nanotubes as substrates which can be decorated with different active catalysts leading to photocatalytic applications (Kukovecz et al 2016, Yang et al 2015). Well-dispersed AuNPs have been used to decorate TiNts in order to increase the efficiency of photocatalytic reactions in general and photocatalytic H2 production, in particular The reasons for this synergetic effect observed are: the strong absorption ability of AuNPs, owing to the SPR effect that improves the visible light response, and the fast electron transfer from TiNts to AuNPs, which traps the photogenerated electrons and prevent their recombination with holes (Yang et al 2015). By AuNPs decoration, we have been able to overcome the problem of large band gap of TiNts, a central issue that restricts the optical response in only UV range and thereby lowers the photocatalytic performance of these semiconductors and had been able to extend the application of this material in the wider visible range
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