Tailoring Noble Metal-Free Ti@TiO2 Photocatalyst for Boosting Photothermal Hydrogen Production

Abstract

In this work, we provide new insights into the design of Ti@TiO2 photocatalyst with enhanced photothermal activity in the process of glycerol reforming. Ti@TiO2 nanoparticles have been obtained by sonohydrothermal treatment of titanium metal nanoparticles in pure water. Variation of sonohydrothermal temperature allows controlling nanocrystalline TiO2 shell on Ti0 surface. At 100 < T < 150°C formation of TiO2 NPs occurs mostly by crystallization of Ti(IV) amorphous species and oxidation of titanium suboxide Ti3O presented at the surface of Ti0 nanoparticles. At T > 150°C, TiO2 is also formed by oxidation of Ti0 with overheated water. Kinetic study highlights the importance of TiO2 nanocrystalline shell for H2 generation. Electrochemical impedance spectroscopy points out more efficient electron transfer for Ti@TiO2 nanoparticles in correlation with photocatalytic data. The apparent activation energy, Ea = (25–31) ± 5 kJ·mol−1, assumes that photothermal effect arises from diffusion of glycerol oxidation intermediates or from water dynamics at the surface of catalyst. Under the heating, photocatalytic H2 emission is observed even in pure water.

Photocatalytic and Sonocatalytic Degradation of EDTA and Rhodamine B over Ti0 and Ti@TiO2 Nanoparticles

“…As also reported in our previous work [18], diffuse reflectance spectra for both Ti 0 and Ti@TiO 2 NPs exhibit a broad band in the UV-NIR spectral range corresponding to the interband transitions of metallic Ti 0 . The presence of TiO 2 on the surface of the metallic NPs promotes the formation of a characteristic absorption peak around 298 nm.…”

“…Recently, it has been reported [18] that the XPS spectrum of air passivated Ti NPs exhibits the presence of Ti 0 and lower oxidation states of titanium (TiO, Ti x O y and Ti 2 O 3 ) at the particle surface in agreement with the XRD analysis revealed the presence of titanium suboxide in Ti 0 NPs. SHT treatment causes disappearance of Ti 0 , TiO, Ti x O y and Ti 2 O 3 peaks, and the experimental XPS spectrum of Ti@TiO 2 NPs can be fitted by defect-free TiO 2 spectrum, indicating effective coating of metallic titanium core.…”

“…1 Table 1. Variation in the composition of air passivated Ti 0 NPs and Ti@TiO 2 obtained from the Rietveld refinement of their XRD patterns [18].…”

“…In addition, recent EIS study indicated a faster charge transfer at the interface of the particle and electrolyte for Ti@TiO 2 compared to Ti 0 NPs. In general, the presence of TiO 2 enhances the charge transfer in such materials, which explains the higher photocatalytic activity of Ti@TiO 2 NPs compared to that of Ti 0 NPs [18].…”

Thermocatalytic Hydrogen Production Through Decomposition of Methane-A Review

“…These include metals like Ni, Fe, and Co, and others. Various studies ( Khan et al, 2016 ; Abdullah et al, 2017 ; Chen et al, 2020b ; Baig et al, 2021 ) have shown the effects of different metal oxide supported catalysts like La 2 O 3 , ZiO 2 , Al 2 O 3 , SiO 2 , and TiO 2 involved in producing hydrogen ( Kim et al, 2011 ; El Hakim et al, 2021 ). In a study by Ibrahim et al , it was found that Fe over La 2 O 3 showed promising results for TMD at temperatures ranged between 500 and 700°C.…”