A porphyrin-conjugated TiO2/CoFe2O4 nanostructure photocatalyst for the selective production of aldehydes under visible light

A ZnTCPP-TiO₂/CoFe₂O₄ nanohybrid easily reusable using a permanent magnet without losing its reactivity for the selective production of aldehydes from a mechanistic point of view.

A facile synthesis of Cs loaded TiO2 nanotube photoelectrode for the removal of 4-chloroguaiacol

In this study, novel Cesium (Cs) doped TiO₂ nanotubes photoelectrode (Cs/TiO₂NTs) were synthesized by simple electrochemical anodization method and characterized by several physicochemical techniques. In particular, the photocatalytic (PC), electrocatalytic (EC) and photoelectrocatalytic (PEC) activity of newly synthesized Cs/TiO₂NTs electrodes was investigated using 4-Chloroguaiacol (4-CG). The effect of operating parameters like Cs concentration, electrolyte concentration, external current and pH on degradation efficacy was examined. PEC oxidation using Cs/TiO₂NTs lead to 92% degradation of 4-CG in 6 h of solar light irradiation under optimized conditions (2.5 mM Cs, 160 mg L^-1 Na₂SO₄, 0.03 A current and pH 3). A comparative assessment between PEC, PC and EC process manifested that PEC process was most efficient than the other two processes and Cs/TiO₂NTs exhibited higher PEC activity than bare-TiO₂ electrodes in terms of degradation and mineralization of organic pollutant. The generation of OH radicals was found to be highest in PEC when compared to EC and PC process. Possible intermediates/byproducts were identified by GC-MS technique and a corresponding tentative degradation pathway has been proposed. Cytotoxicity study showed that PEC has potential to detoxify 4-CG. Hence, combination of TiO₂ electrodes decorated with Cs metal can act as a highly efficient photoelectrode for the degradation of hazardous pollutants.

Rational design and synthesis of highly oriented copper-zinc ferrite QDs/titania NAE nano-heterojunction composites with novel photoelectrochemical and photoelectrocatalytic behaviors

This work reported that novel highly oriented and vertically aligned stoichiometric copper- and zinc-based ferrites, i.e., Cu0.5Zn0.5Fe2O4 quantum dots (QDs) anchored with TiO2 nanotube array electrode (NAE) composites, with n-n nano-heterojunctions and highly effective simulated solar light harvesting could be successfully achieved via electrochemical anodization followed by a vacuum-assisted impregnation strategy. It has been observed that Cu0.5Zn0.5Fe2O4 QDs/TiO2 NAE composites exhibit distinctly enhanced visible light photoelectrocatalytic (PEC) performance toward the degradation of typical pollutants including sulfamethoxazole (SMX) and methylene blue (MB) as compared to that of pristine TiO2 NAEs, which can be attributed to the synergistic effect of heterostructures with strong interfacial interaction and abundant 1D nanotube array structures to facilitate efficient spatial charge separation and interfacial transfers. The cocatalyst-anchoring of ternary oxides with derived spinel crystal structures onto nanotube arrays forming novel nanocomposites have obviously achieved remarkably enhanced photoelectrochemical (PE) conversion efficiencies, up to a dedicated value of 3.75%, under visible light irradiation as compared to that of 0.88% for aligned standalone TiO2 NAEs. Transient absorption spectroscopy quantitatively indicated long-lived photo-holes with lifetimes exceeding 72.23 μs generated among Cu0.5Zn0.5Fe2O4 QDs/TiO2 NAE nanocomposites. Electron spinning resonance (ESR) demonstrated that more ˙O2- species derived from molecular uptake played the predominant role in the PEC oxidations of SMX and MB species. Moreover, the binding energy of the onset edge (Evf) and Fermi level (Ef) of Cu0.5Zn0.5Fe2O4 QDs/TiO2 NAEs indicated that Cu0.5Zn0.5Fe2O4 QDs modification could considerably enhance the visible light harvesting and adsorption properties of TiO2 NTs. Furthermore, Cu0.5Zn0.5Fe2O4 QDs/TiO2 NAEs achieved up to 50% PEC degradation efficiency and 52.4% COD removal with regard to practical textile wastewater when irradiated by simulated sunlight. This work has provided new insights into the molecular tailing and coupling of multiple spinels with TiO2 NTs possessing remarkable visible light harvesting and sensitization characteristics, which would offer a prospective strategy toward designing highly efficient and easily recyclable photocatalytic materials for environmental remediation and solar energy utilizations and conversions both simultaneously and standalone.

Fabrication of highly visible-light-responsive ZnFe2O4/TiO2 heterostructures for the enhanced photocatalytic degradation of organic dyes

A novel visible-light-sensitive ZnFe₂O₄–TiO₂ photocatalyst was fabricated by coupling 0.2–2 wt% p-type ZnFe₂O₄ narrow bandgap material with n-type anatase TiO₂.