Zn2SnO4 ternary metal oxide for ultraviolet radiation filter application: a comparative study with TiO2 and ZnO.

Ultraviolet (UV) radiation causes serious health risks. Inorganic metal oxides, such as titanium dioxide (TiO2) and zinc oxide (ZnO), have long been recognized for their effectiveness as UV radiation filters/blockers in sunscreen formulations. TiO2 and ZnO as UV-blocking materials have some limitations and issues such as producing harmful radicals and toxicity, respectively. As a result, there is a growing need to develop efficient and safe UV-blocking materials to overcome these limitations associated with the conventional TiO2 and ZnO materials. Zinc stannate (Zn2SnO4), as a ternary metal oxide, is expected to be a promising candidate due to its optical properties and potential for UV-blocking capability. This study presents a comprehensive investigation into the development and characterization of Zn2SnO4 as a potential alternative UV filter to TiO2 and ZnO. The fundamental characteristics, including structural, optical, and photocatalytic characteristics, as well as cell viability, were investigated for two Zn2SnO4 morphologies: cubic aggregate Zn2SnO4 nanoparticles (ZTO CANP) and Zn2SnO4 nanoparticles (ZTO NP), which were compared with the performance of TiO2 nanoparticles (TiO2 NP) and ZnO nanoparticles (ZnO NP). Interestingly, in addition to their promising UVB and partial UVA blocking properties, ZTO CANP and ZTO NP were found to be relativity photocatalytically inactive materials, which means they produce less free radical species as in the case of TiO2 NP, and they cannot be considered as toxic materials as in the case of ZnO NP. To the best of our knowledge, this is the first direct comparison study examining the performance of Zn2SnO4 ternary metal oxide for its potential use as a UV filter. Further research and optimization need to be conducted on these materials, particularly on ZTO CANP as a promising alternative UV filter.

This study investigates the development and characterization of zinc stannate (Zn₂SnO₄) as a potential alternative UV-blocking material for sunscreen formulations. Despite their effectiveness as UV radiation filters, TiO₂ and ZnO have harmful radicals and toxicity, respectively. The study focuses on two Zn₂SnO₄ morphologies: cubic aggregate Zn₂SnO₄ nanoparticles (ZTO CANP) and Zn₂SnO₄ nanoparticles (ZTO NP). They showed promising UVB and partial UVA blocking. Their UV blocking range seems to be an average of the blocking profile of TiO₂ and ZnO. ZTO CANP and ZTO NP are found to be photocatalytically inactive, producing less free radical species and not being toxic. To the best of our knowledge, this is the first direct comparison study examining the performance of Zn₂SnO₄ ternary metal oxide for its potential use as a UV filter.

Solvothermally synthesized anatase TiO2 nanoparticles for photoanodes in dye-sensitized solar cells.

Many researchers working on the development of Dye-sensitized solar cells (DSCs) continue to focus on the synthesis of photoanode materials with high surface area, along with high light scattering ability to enhance light harvesting efficiency (LHE). On the other hand, dye packing density, which can also affect the LHE significantly, is often overlooked. Solvothermally synthesized anatase TiO2 nanoparticles (SANP) were obtained by a new and simple approach using a mixed solvent, ethanol and acetic acid. SANP were applied as a photoanodes material in DSCs using a metal-free organic dye (D149) or organometallic dye (N719) dyes. The dye loading (packing density) was examined in term of the isoelectric point (IEP) and the contribution of this, in addition to light scattering effects were shown to control the devices photovoltaic efficiency of the devices; specifically when compared with ones employing commercially available TiO2 nanoparticles (either transparent or a bilayer structure with a transparent layer and a scattering one). SANP photoanodes sensitized with D149 dye were found to be optimised at 10 µm, yielding photovoltaic conversion efficiencies of 6.9%, superior to for transparent or transparent + scattering films from the commercial source (5.6% and 5.9%, respectively). Further to this, an efficiency of 7.7% PCE was achieved using a SANP photoanode sensitized with N719 dye, with 7.2% seen for the transparent photoanode and 7.9% with a scattering layer. The high efficiencies of devices based on of SANP photoanode are attributed to the high dye loading capability in addition to good light scattering. A further point of interest is that even with the increased reactivity of the surface towards dye adsorption, we did not observe any significant increase in recombination with the redox mediator, presumably due to this increased dye loading providing better shielding.

Solvothermally Synthesized Hierarchical Aggregates of Anatase TiO2 Nanoribbons/Nanosheets and Their Photocatalytic-Photocurrent Activities.

Hierarchical aggregates of anatase TiO2 nanoribbons/nanosheets (TiO2-NR) and anatase TiO2 nanoparticles (TiO2-NP) were produced through a one-step solvothermal reaction using acetic acid or ethanol and titanium isopropoxide as solvothermal reaction systems. The crystalline structure, crystalline phase, and morphologies of synthesized materials were characterized using several techniques. According to our findings, both TiO2-NR and TiO2-NP were found to have polycrystalline structures, with pure anatase phases. TiO2-NR has a three-dimensional hierarchical structure made up of aggregates of TiO2 nanoribbons/nanosheets, while TiO2-NP has a nanoparticulate structure. The photocatalytic and photocurrent activities for TiO2-NR and TiO2-NP were investigated and compared with the widely used commercial TiO2 (P25), which consists of anatase/rutile TiO2 nanoparticles, as a reference material. Our findings showed that TiO2-NR has higher photocatalytic and photocurrent performance than TiO2-NP, which are both, in turn, higher than those of P25. Our developed solvothermal method was shown to produce a pure anatase TiO2 phase for both synthesized structures, without using any surfactants or any other assisted templates. This developed solvothermal approach, and its anatase TiO2 nanostructure output, has promising potential for a wide range of energy harvesting applications, such as water pollution treatment and solar cells.

The effect of amorphous TiO2 in P25 on dye-sensitized solar cell performance.

P25 is one of the most widely used forms of titanium(iv) oxide (TiO2), routinely utilised in dye-sensitised solar cells (DSCs), where it is often employed as a control, in spite of its poorly defined nature and the typically low device efficiency (or possibly because of this). Work by Park in 2000 and later by Lin et al. suggests that the rutile component might not be to blame for this, as has often been claimed. Recently it has been observed that P25 has quite a sizable amorphous content. A method to selectively remove this non-crystalline material has been developed, allowing for scrutiny of the role this amorphous material plays. Here we compare hydrothermally treated P25 (H-P25) with the as-received material, realizing solar-to-electric conversion efficiencies of 5.3% and 3.2% respectively. More importantly, this reveals important information about the detrimental effect of amorphous TiO2 on DSC performance, with broader implications, as most researchers do not actively examine their synthesized materials for the presence of an amorphous component.

Aggregated mesoporous nanoparticles for high surface area light scattering layer TiO2 photoanodes in Dye-sensitized Solar Cells.

Hierarchically structured aggregates, consisting of TiO2 nanoparticles were produced via one-step solvothermal syntheses with a mixed solvent system containing both acetic acid and ethanol. Two of the resulting structures, one ~700 nm and the other ~300 nm in diameter, were found to be comprised of 8.5 nm and 10.5 nm anatase crystals, and possess specific surface areas of 138 and 106 m2 g-1 respectively. These particles were incorporated into Dye-sensitized Solar Cells (DSCs) as high surface area scattering layers, along with a layer of a transparent material. Solar-to-electric conversion efficiencies (PCE) of 9.1% and 8.2% were recorded using these aggregated particles as compared to those of commonly used large particles scattering layer 7.4%.