Fabrication of CDs/CdS-TiO2 ternary nano-composites for photocatalytic degradation of benzene and toluene under visible light irradiation

Recent Progress of Carbon Dots for Air Pollutants Detection and Photocatalytic Removal: Synthesis, Modifications, and Applications

Rapid industrialization has inevitably led to serious air pollution problems, thus it is urgent to develop detection and treatment technologies for qualitative and quantitative analysis and efficient removal of harmful pollutants. Notably, the employment of functional nanomaterials, in sensing and photocatalytic technologies, is promising to achieve efficient in situ detection and removal of gaseous pollutants. Among them, carbon dots (CDs) have shown significant potential due to their superior properties, such as controllable structures, easy surface modification, adjustable energy band, and excellent electron-transfer capacities. Moreover, their environmentally friendly preparation and efficient capture of solar energy provide a green option for sustainably addressing environmental problems. Here, recent advances in the rational design of CDs-based sensors and photocatalysts are highlighted. An overview of their applications in air pollutants detection and photocatalytic removal is presented, especially the diverse sensing and photocatalytic mechanisms of CDs are discussed. Finally, the challenges and perspectives are also provided, emphasizing the importance of synthetic mechanism investigation and rational design of structures.

The structure-activity relationship of aromatic compounds in advanced oxidation processes：a review

Advanced oxidation processes (AOPs) are widely used as efficient technologies to treat highly toxic and harmful substances in wastewater. Taking the most representative aromatic compounds (monosubstituted benzenes, substituted phenols and heterocyclic compounds) as examples, this paper firstly introduces their structures and the structural descriptors studied in AOPs before, and the influence of structural differences in AOPs with different reactive oxygen species (ROS) on the degradation rate was discussed in detail. The structure-activity relationship of pollutants has been previously analyzed through quantitative structure-activity relationship (QSAR) model, in which ROS is a very important influencing factor. When electrophilic oxidative species attacks pollutants, aromatic compounds with electron donating groups are more favorable for degradation than aromatic compounds with electron donating groups. While nucleophilic oxidative species comes to the opposite conclusion. The choice of advanced oxidation processes, the synergistic effect of various active oxygen species and the used catalysts will also change the degradation mechanism. This makes the structure-dependent activity relationship uncertain, and different conclusions are obtained under the influence of various experimental factors.

Synthesis and application of CdS nanoparticles-decorated core-shell Ag@Ni nanohybrids for visible-light spectrophotometric assay of sulfide in aqueous sample

Novel Ag@Ni nanosphere decorated with CdS NPs (Ag@Ni-CdS NCs) was synthesized by one step chemical synthesis method. The fabricated NCs were characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), fourier transfer infra-red spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta sizer and particle size analyzer. TEM and XRD confirmed the Ag in core and Ni in shell for the effective formation of Ag@Ni core shell nanosphere. EDAX and XPS spectra of NCs confirms the formation of Ag@Ni-CdS NCs. Zeta potential and particle size of the NCs was found to be 29.5 ± 1.5 mV and 24 ± 1 nm respectively. The complete loss in the peak intensity of Ag@Ni-CdS NCs (localized surface plasmon resonance (LSPR)) at ∼410 nm in presence of S^2- ions was observed which indicates its selective detection towards S^2- ions. The sulfide ion sensing by Ag@Ni-CdS NCs was due to the successive oxidation of Ag results in the formulation of Ag²⁺ ions in the system, which causes the diminishing of LSPR band of NCs. The limit of detection (LOD) of S^2- ions by Ag@Ni-CdS NCs was calculated to be of 2.66 nM. The combination of CdS NPs with core-shell Ag@Ni nanosphere guides a promising strategy for S^2- ions detection from environmental polluted samples.

Efficient Photocatalytic Degradation of Gaseous Benzene and Toluene over Novel Hybrid PIL@TiO2/m-GO Composites

In this work, the PIL (poly ionic liquid)@TiO2 composite was designed with two polymerized ionic liquid concentrations (low and high) and evaluated for pollutant degradation activity for benzene and toluene. The results showed that PIL (low)@TiO2 composite was more active than PIL (high)@TiO2 composites. The photodegradation rate of benzene and toluene pollutants by PIL (low)@TiO2 and PIL (high)@TiO2 composites was obtained as 86% and 74%, and 59% and 46%, respectively, under optimized conditions. The bandgap of TiO2 was markedly lowered (3.2 eV to 2.2 eV) due to the formation of PIL (low)@TiO2 composite. Besides, graphene oxide (GO) was used to grow the nano-photocatalysts’ specific surface area. The as-synthesized PIL (low)@TiO2@GO composite showed higher efficiency for benzene and toluene degradation which corresponds to 91% and 83%, respectively. The resultant novel hybrid photocatalyst (PIL@TiO2/m-GO) was prepared and appropriately characterized for their microstructural, morphology, and catalytic properties. Among the studied photocatalysts, the PIL (low)@TiO2@m-GO composite exhibits the highest activity in the degradation of benzene (97%) and toluene (97%). The ultimate bandgap of the composite reached 2.1 eV. Our results showed that the as-prepared composites hold an essential role for future considerations over organic pollutants.

Dual-function surface hydrogen bonds enable robust O2 activation for deep photocatalytic toluene oxidation

Extensive hydrogen-bonds between the hydroxyl-rich BiOCl surface and phosphoric acid significantly facilitate oxygen vacancy formation, O₂ activation, and deep toluene oxidation.

Oxygen vacancy-induced donor–acceptor-conjugated microporous poly(triphenylamine–benzothiadiazole)/TiO2 as a Z-scheme heterojunction photocatalyst towards a visible-light-driven degradation of bisphenol A

A Z-scheme TPABT/TiO₂ heterostructure induced by oxygen vacancies exhibited high photocatalytic performance for the degradation of bisphenol A under visible light irradiation.

Photocatalytic membrane combined with biodegradation for toluene oxidation

Photocatalytic membrane coupled to biodegradation offers potential for degrading volatile organic compounds (VOCs) in photocatalytic membrane biofilm reactor. An intimately coupled photocatalysis and biodegradation reactor was operated in continuous operation for 500 days to treat simulated waste gas containing toluene. Toluene removal efficiency obtained 99%, with the elimination capacity of 550 g m^-3·h^-1. Membrane photocatalysis coupled to biodegradation was created to improve toluene removal from 11 to 20%. The dominant genera were Lysinibacillus, Hydrogenophaga, Pseudomonas at 30 d, Rudaea, Dongia, Litorilinea at 230 d xyl, Tod, Tcb, Bed, Tmo, Tbu, Tou, Dmp, Cat were functional genes of toluene metabolism, as shown by16S rDNA and metagenomic sequencing. Photocatalysis destroyed part of the toluene into biodegradable intermediates that were immediately mineralized by microorganisms in biofilm, some toluene was directly degraded by toluene degrading bacterial community into carbon dioxide and water. The novel hybrid photocatalytic membrane biofilm reactor is a cost-effective and robust alternative to VOCs treatment.