Per- and polyfluoroalkyl substances (PFAS) are fluorinated and refractory pollutants that are ubiquitous in industrial wastewater. Photocatalytic destruction of such pollutants with catalysts such as TiO2 and ZnO is an attractive avenue for removal of PFAS, but refined forms of such photocatalysts are expensive. This study, for the first time, utilized milled unrefined raw mineral ilmenite, coupled to UV-C irradiation to achieve mineralization of the two model PFAS compounds perfluorooctanoic acid (PFOA) and perfluoro octane sulfonic acid (PFOS). Results obtained using a bench-scale photocatalytic reactor system demonstrated rapid removal kinetics of PFAS compounds (>90% removal in less than 10 h) in environmentally-relevant concentrations (200-1000 ppb). Raw ilmenite was reused over three consecutive degradation cycles of PFAS, retaining >80% removal efficiency. Analysis of degradation products indicated defluorination and the presence of shorter-chain PFAS intermediates in the initial samples. End samples indicated the disappearance of short-chain PFAS intermediates and further accumulation of fluoride ions, suggesting that original PFAS compounds underwent mineralization due to an oxygen-radical-based photocatalytic destruction mechanism induced by TiO2 present in ilmenite and UV irradiation. The outcome of this study implies that raw ilmenite coupled to UV-C is suitable for cost-effective reactor operation and efficient photocatalytic destruction of PFAS compounds.

The environmental contamination caused by organophosphorus pesticides (for example, triazophos) is an escalating concern. To mitigate this issue, this study introduces a novel Al6Si2O13/WO2.72 (ASO/WO) nanocomposite photocatalyst, which markedly enhances the photocatalytic degradation of triazophos. The optimized nanocomposite material with a 60.0 % ASO loading (60-ASO/WO) achieves a degradation rate of 86.3 % for triazophos within 140.0 min, marginally exceeding 60-ASO/WO3 (72.6 %) and significantly outperforming individual ASO (65.0 %), WO (59.5 %), and WO3 (56.2 %). This catalyst retains 88.9 % of its activity after five cycles, showcasing exceptional efficiency and stability. Additionally, its electrochemical surface area (ECSA, 310.0 cm2), total organic carbon (TOC, removal rate of 73.7 %), photocurrent, and electrochemical impedance are all optimal. X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and theoretical calculations elucidate the critical role of oxygen vacancies and the S-scheme heterojunction in augmenting charge separation and photocatalytic performance, corroborating the synergistic effect of oxygen defects and the S-scheme. While individual factors can enhance photocatalytic activity, their combination results in a more pronounced effect. Liquid chromatography-mass spectrometry (LCMS) identifies the principal degradation intermediates, including 1-phenyl-3-hydroxy-1, 2, 4-triazole, diethyl thiophosphate, and 3, 5, 6-trichloro-2-pyridinol, underscoring the material\'s potential in environmental remediation.

The study presents Ag2CrO4/Fe2O3/CeO2 ternary nanocomposite, based on Fe2O3/CeO2 binary composites, which demonstrated excellent photocatalytic performance in the photodegradation of methylene blue under solar irradiation. The Ag2CrO4/Fe2O3/CeO2 nanocomposites was orthorhombic, ilmenite, and cubic-fluorite phases of Ag2CrO4, Fe2O3, and CeO2, respectively, according to the XRD examination. A strong bond between Ag2CrO4, Fe2O3, and CeO2 within the nanocomposite was demonstrated by the SEM and TEM investigations. Moreover, it was discovered that the coupling of Ag2CrO4 and Fe2O3 caused a red shift and moved CeO2 absorption edge from the UV to the visible spectrum. The reason behind this is that the band gap of CeO2 reduced 2.85 to 2.69 eV and the absorbance band intensity increased in visible region. Utilizing visible light, Ag2CrO4/Fe2O3/CeO2 ternary nanocomposites exhibit enhanced photocatalytic properties (98.90%) for the degradation of methylene blue (MB) within 100 min. The long-term reliability and recyclability of the photocatalyst were explored through 3 successive cycles. An active radical quenching test was conducted to elucidate the involvement of O2 - and OH which are the primary reactive species in the photocatalytic breakdown of MB. Ag2CrO4/Fe2O3/CeO2 ternary nanocomposites displayed notable improvements in photodegradation activity, making them well suited for the effective removal of hazardous dyes present in textile effluents.

Assembly of different metal-organic frameworks (MOFs) into hybrid MOF-on-MOF heterostructures has been established as a promising approach to develop synergistic performances for a variety of applications. Here, we explore the performance of a MOF-on-MOF heterostructure by epitaxial growth of MIL-88B(Fe) onto UiO-66(Zr)-NH2 nanoparticles. The face-selective design and appropriate energy band structure alignment of the selected MOF constituents have permitted its application as an active heterogeneous photocatalyst for solar-driven water splitting. The composite achieves apparent quantum yields for photocatalytic overall water splitting at 400 and 450 nm of about 0.9%, values that compare much favorably with previous analogous reports. Understanding of this high activity has been gained by spectroscopic and electrochemical characterization together with scanning transmission and transmission electron microscopy (STEM, TEM) measurements. This study exemplifies the possibility of developing a MOF-on-MOF heterostructure that operates under a Z-scheme mechanism and exhibits outstanding activity toward photocatalytic water splitting under solar light.

Herein, it is demonstrated that 0D/2D design of zinc sulfide quantum dots encapsulated with yttrium tungstate nanosheets, which were subsequently used to increase the removal of brilliant blue (BB), methyl red (MR) dyes and doxycycline drug using UV-visible light. The produced ZnS-Y2WO6 nanohybrids exhibited excellent catalytic activity, reaching degradation efficiencies of around 89.92%, 80% and 85.51 % for BB, MR dyes and doxycycline drug, respectively, with a minimum irradiation duration of 120, 60 and 125 min. These nanohybrids outperformed Y2WO6 in terms of photocatalytic efficacy due to enhanced light absorption, efficient charge transfer, and decreased charge carrier recombination between ZnS and Y2WO6 nanoparticles. The synergistic combination of ZnS and Y2WO6 nanoparticles resulted in multiple active sites on the composite surface. Furthermore, the ZnS-Y2WO6 nanohybrids maintained excellent degradation efficiencies of 79.45% and 70.12% for BB and MR dyes, respectively, even after five consecutive cycles, with no significant loss of catalytic activity. The produced ZnS-Y2WO6 nanohybrids were thoroughly analyzed utilizing a variety of analytical methods. Furthermore, the degradation of organic dyes and doxycycline drug related possible mechanism were examined using experimental data, indicating the potential of ZnS-Y2WO6 nanohybrids as excellent photocatalytic materials for oxidizing organic dyes and drugs in aquatic conditions.

The generation of hydrogen through photocatalysis is a fascinating technology for addressing environmental concerns and the energy crisis. Nevertheless, the quest for cost-effective, stable, and efficient photocatalysts in the realm of energy conversion remains a significant challenge. Herein, we designed novel InVO4/Ti3C2 MXene (IVTC) heterostructures by employing acid etching to produce Ti3C2 MXene with an accordion-like morphology, using the hydrothermal technique for the production of orthorhombic InVO4 nanoparticles (NPs), and integrating them through a self-assembly approach. Both field-emission scanning electron microscopy and HRTEM analyses revealed a consistent distribution of InVO4 NPs with an average size of 43.4 nm on both surfaces and between the sheets of Ti3C2 MXene. The intimate interface between the Ti3C2 MXene nanosheet and InVO4 suppressed carrier recombination and promoted charge transfer, thereby boosting photocatalytic H2 production. Under visible light exposure, the rate of hydrogen evolution is enhanced in IVTC heterostructures containing an optimized 10% loading of InVO4, exhibiting over a 3-fold increase compared to pristine InVO4 NPs, maintaining efficiency across four cycles. This research presents a promising method for designing and creating high-efficiency heterostructures possessing excellent visible-light-driven photocatalytic activity for H2 evolution.

A superficial, one step thermal polycondensation method has been employed for the manifestation of graphene like graphitic carbon nitride (g-C3N4) catalyst. The as synthesized g-C3N4 was well characterized by SEM and EDAX analysis, XRD, ATR-IR, FTIR, Fluorescence spectroscopy, Raman spectroscopy and UV-Visible spectroscopy which provide structural, morphological assemblage relating to the structure of g-C3N4. The g-C3N4 showed that an outstanding photochemical stability, morphology, conductive carbon framework and superior photocatalytic activity. The band gap value of g-C3N4 is 2.34 eV determined using Tauc plot. Due to low band gap (2.33 eV) and unique morphology which provides high separation and migration ability of the photogenerated charges, the g-C3N4 shows enhanced photocatalytic activity for the removal of many organic dyes such as Rhodamine B (RhB), Crystal Violet (CV), Methylene Blue (MB), Methyl Orange (MO), Naphthol Orange (NO) and a phenol derivative, p-Nitrophenol (p-NP). Among them, RhB dye was degraded almost 81 % at 90 min under sunlight irradiation in presence g-C3N4 while other dyes and p-NP was degraded at lower rate. From the experimental data, it was found that MO and p-NP degradation rate was least. The rate constant for degradation of Rh B is 1.1 × 10-2 min-1. Therefore, g-C3N4 can be used as an efficient photocatalyst for waste water treatment by the removal of such organic pollutants.

Atomically dispersed active sites in a photocatalyst offer unique advantages such as locally tuned electronic structures, quantum size effects, and maximum utilization of atomic species. Among these, asymmetric atomic dual-sites are of particular interest because their asymmetric charge distribution generates a local built-in electric potential to enhance charge separation and transfer. Moreover, the dual sites provide flexibility for tuning complex multielectron and multireaction pathways, such as CO2 reduction reactions. The coordination of dual sites opens new possibilities for engineering the structure-activity-selectivity relationship. This comprehensive overview discusses efficient and sustainable photocatalysis processes in photocatalytic CO2 reduction, focusing on strategic active-site design and future challenges. It serves as a timely reference for the design and development of photocatalytic conversion processes, specifically exploring the utilization of asymmetric atomic dual-sites for complex photocatalytic conversion pathways, here exemplified by the conversion of CO2 into valuable chemicals.

In the realm of solar energy utilization, there is a growing focus on designing and implementing effective photocatalytic systems, for the conversion of solar energy into valuable chemical fuels. The potential of Covalent Organic Polymers (COPs) as photocatalysts for visible-light-driven organic transformation has been widely investigated, positioning them as promising candidates in this field. In the design of COPs, introducing a donor-acceptor arrangement facilitates the transfer of electrons from the donor to the acceptor, creating a charge transfer complex and leading to enhanced conductivity and improved charge separation. Here we present a novel hydrazone-linked covalent organic polymer ETBC-PyHz containing TPE donor and pyridine acceptor. Utilizing this, an efficient method has been developed for an oxidative cross-coupling reaction involving C-S bond formation. This process involves arylhydrazines and arenethiols, and results in the production of unsymmetrical diaryl sulfides via the formation of aryl and thioarene radicals. This conversion holds significant importance because the byproducts produced during the process are nitrogen and water, making it environmentally benign.

Polyaniline (PANI), a typical organic photocatalyst, has an adjustable structure and good stability, can be easily synthesized on a large scale, and is economical. PANI is doped with ions to regulate its internal structure and improve its photocatalytic performance. However, its photocatalytic performance is limited by the doping concentration and its intrinsic properties, hindering its further application. Herein, PANI films with a piezo-photocatalytic function are fabricated to improve photocatalytic performance and explore their self-powered environmental purification property. PANI/poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) sandwich films, with PVDF-HFP as the interlayer, are prepared by introducing a piezoelectric field into PANI photocatalysts, thereby achieving excellent piezo-photocatalytic performance. The as-fabricated piezo-photocatalyst degrades methyl orange at a rate of 91.2% after 60 min under magnetic stirring. Owing to the low Young\'s modulus of the all-organic catalyst, self-powered purification is realized using the PANI/PVDF-HFP film. Leaf surfaces are functionalized by loading the film in them for removing pollutants under sunlight and water flow. Thus, this study proposes a common strategy, wherein a piezoelectric interlayer is introduced to load the organic photocatalyst for preparing an all-organic piezo-photocatalyst. This piezo-photocatalyst can be easily recycled and responds to weak forces, realizing its application for self-powered environmental purification.