Solar photocatalysts: non-metal (C, N, and S)-doped ZnO synthesized through an industrially sustainable approach for environmental remediation applications.

One of the biggest issues the world is currently experiencing is the scarcity of pure water due to the contamination of pure water by human activities. Highly efficient, semiconducting photocatalytic materials have great potential as future catalytic materials for facilitating the clean-up process of contaminated water. Among the many semiconductor photocatalysts, non-metal-doped zinc oxide (ZnO) nanoparticles have attracted special attention in the scientific field for environmental remediation applications.

Probing Water and CO₂ Interactions at the Surface of Collapsed Titania Nanotubes Using IR Spectroscopy.

Collapsed titania nanotubes (cTiNT) were synthesized by the calcination of titania nanotubes (TiNT) at 650 °C, which leads to a collapse of their tubular morphology, a substantial reduction in surface area, and a partial transformation of anatase to the rutile phase. There are no significant changes in the position of the XPS responses for Ti and O on oxidation or reduction of the cTiNTs, but the responses are more symmetric than those observed for TiNTs, indicating fewer surface defects and no change in the oxidation state of titanium on oxidative and/or reductive pretreatment. The interaction of H₂O and CO₂ with the cTiNT surface was studied.

Effect of Dimensionality on the Photocatalytic Behavior of Carbon-Titania Nanosheet Composites: Charge Transfer at Nanomaterial Interfaces.

Due to their unique optoelectronic structure and large specific surface area, carbon nanomaterials have been integrated with titania to enhance photocatalysis. In particular, recent work has shown that nanocomposite photocatalytic performance can be improved by minimizing the covalent defect density of the carbon component. Herein, carbon nanotube-titania nanosheet and graphene-titania nanosheet composites with low carbon defect densities are compared to investigate the role of carbon nanomaterial dimensionality on photocatalytic response.

Minimizing graphene defects enhances titania nanocomposite-based photocatalytic reduction of CO2 for improved solar fuel production.

With its unique electronic and optical properties, graphene is proposed to functionalize and tailor titania photocatalysts for improved reactivity. The two major solution-based pathways for producing graphene, oxidation-reduction and solvent exfoliation, result in nanoplatelets with different defect densities. Herein, we show that nanocomposites based on the less defective solvent-exfoliated graphene exhibit a significantly larger enhancement in CO(2) photoreduction, especially under visible light.

Role of water and carbonates in photocatalytic transformation of CO2 to CH4 on titania.

Using the electron paramagnetic resonance technique, we have elucidated the multiple roles of water and carbonates in the overall photocatalytic reduction of carbon dioxide to methane over titania nanoparticles. The formation of H atoms (reduction product) and (•)OH radicals (oxidation product) from water, and CO(3)(-) radical anions (oxidation product) from carbonates, was detected in CO(2)-saturated titania aqueous dispersion under UV illumination. Additionally, methoxyl, (•)OCH(3), and methyl, (•)CH(3), radicals were identified as reaction intermediates.