Graphitic carbon nitride/SmFeO3 composite Z-scheme photocatalyst with high visible light activity

Synthesis of samarium orthoferrite-based perovskite nanoparticles as a turn-on fluorescent probe for trace level detection of picric acid

Picric acid (2,4,6-trinitrophenol, PA) is a common constituent of many powerful explosives, thus, development of the chemical probes for trace level detection of PA is a crucial current challenge in both public security and environmental protection. In this work, the applicability of the new perovskite-type oxide SmFeO₃ nanoparticles as an inorganic fluorescence turn-on probe for the selective and sensitive recognition of PA in organic and aqueous media was investigated. The synthesis of nanoparticles SmFeO₃ was carried out using the surfactant-assisted templating approach which proceeds through the sol-gel process based on nonionic surfactant Triton X-100. The synthesized SmFeO₃ nanoparticles exhibited strong solvent-dependent emission at 330 nm wavelength with absorption maxima at 225 nm. Among the tested explosives, the probe showed the highest sensitivity and selectivity for detecting PA in water and water/acetonitrile mixture. The response time for detecting PA was less than 5 s. The limits of detection for PA in acetonitrile and water/acetonitrile mixture were 2.1 µM and 1.1 µM, respectively. Furthermore, to investigate the nature of the fluorescence turn-on sensing mechanism, the experimental data of the dynamic light scattering (DLS) technique and zeta-potential were used. Both techniques confirmed the aggregation-induced emission (AIE) mechanism for detection of PA with the synthesized turn-on probe. The results of the present work will have a considerable impact on the development and applications of a new class of inorganic fluorescence turn-on probes for the detection of PA.

Application of perovskite oxides and their composites for degrading organic pollutants from wastewater using advanced oxidation processes: Review of the recent progress

In the recent years, perovskite oxides are gaining an increasing amount of attention owing to their unique traits such as tunable electronic structures, flexible composition, and eco-friendly properties. In contrast, their catalytic performance is not satisfactory, which hinders real wastewater remediation. To overcome this shortcoming, various strategies are developed to design new perovskite oxide-based materials to enhance their catalytic activities in advanced oxidation process (AOPs). This review article is to provide overview of basic principle and different methods of AOPs, while the strategies to design novel perovskite oxide-based composites for enhancing the catalytic activities in AOPs have been highlighted. Moreover, the recent progress of their synthesis and applications in wastewater remediation (pertaining to the period 2016-2022) was described, and the related mechanisms were thoroughly discussed. This review article helps scientists to have a clear outlook on the selection and design of new effective perovskite oxide-based materials for the application of AOPs. At the end of the review, perspective on the challenges and future research directions are discussed.

Encapsulation of spinel CuCo2O4 hollow sphere in V2O5-decorated graphitic carbon nitride as high-efficiency double Z-type nanocomposite for levofloxacin photodegradation

In this study, spinel CuCo₂O₄ (CCO) with a hierarchical hollow sphere morphology was encapsulated in V₂O₅-decorated ultra-wrinkled graphitic carbon-nitride (VO-UCN) for the first time via a facile glycerol-assisted solvothermal method in the interest of developing a novel high-efficiency double Z-type nano-photocatalyst (denoted as VO-UCN@CCO). The remarkable physicochemical features of the as-prepared nano-photocatalysts were verified using diverse characterization techniques including TGA, XRD, FT-IR, FE-SEM, TEM, BET, UV-vis DRS, PL, EIS, and transient photocurrent techniques. Herein, VO-UCN@CCO nanocomposite was employed for the photodisintegration of levofloxacin (LVOF) antibiotic under visible-light irradiation and the impact of certain operative reaction system variables was explored in an effort to optimize the photocatalytic capability. The 40% loading of CCO in VO-UCN@CCO nanocomposite was found to display maximum photocatalytic performance (about 95%) for LVOF photodecomposition, which was 9.3, 6.6, and 13.8 times greater when compared with pristine VO, UCN, and CCO, respectively. A high capability was observed for as-prepared photocatalyst during reusability tests and near 90% degradation efficiency was obtained in the sixth run. The complete mineralization of LVOF was achieved by the VO-UCN@CCO photocatalyst process after 300 min of reaction. An excellent synergy factor towards the degradation of LVOF was obtained for VO-UCN@CCO compared to each of its components alone. This peculiar design is envisaged to provide new inspirations for ameliorating the photocatalytic decontamination of tenacious and non-biodegradable species present in real wastewater.

Enhanced photocatalytic degradation of 4-chlorophenol under visible light over carbon nitride nanosheets with carbon vacancies

Two-dimensional graphitic carbon nitride (g-C₃N₄, GCN) is considered as one of the promising visible light-responsive photocatalysts for energy storage and environmental remediation. However, the photocatalytic performance of pristine GCN is restricted by the inherent shortcomings of rapid charge carrier recombination and limited absorption of visible light. Vacancy engineering is widely accepted as the auspicious approach for boosting the photocatalytic activity of GCN-based photocatalysts. Herein, a magnesium thermal calcination method has been developed to reconstruct GCN, in which magnesium serves as a carbon etcher for introducing carbon vacancies and pores into GCN (V_c-GCN). The fabricated V_c-GCN demonstrates excellent photocatalytic performances of degrading hazardous 4-chlorophenol under visible light irradiation benefiting from the improved carrier separating and light absorption ability as well as rich reactive sites. The optimal V_c-GCN sample delivers 2.3-fold enhancement from the pristine GCN. The work provides a tactic to prepare GCN photocatalysts with controllable carbon vacancies and for a candidate for the degradation of organic pollutants from the environment.

Ultrathin S-doped graphitic carbon nitride nanosheets for enhanced sulpiride degradation via visible-light-assisted peroxydisulfate activation: Performance and mechanism

The wide use and distribution of sulpiride (SP) has caused potential threats to the water environment and human health. In this study, ultrathin S-doped graphitic carbon nitride nanosheets (US-CN) was successfully synthesized and characterized, and its SP removal efficiency was evaluated under various conditions via the visible-light-assisted peroxydisulfate (PDS) activation method. The degradation pathways and mechanism were also discussed through quenching experiments, density functional theory (DFT) calculations, and intermediate products detection. After sulfur doping and ultrasonic treatment, graphitic carbon nitride (CN) possessed an ultra-thin and porous structure, which facilitated the electronic distribution and more photocurrent, thus resulting in the excellent stability and removal efficiency for SP via PDS activation upon visible light irradiation. The singlet oxygen (¹O₂) generated by the US-CN/PDS/VL system played a significant role in SP degradation. Based on the bonds of electron-rich atoms fracturing and the SO₂ extrusion, the SP degradation pathway was proposed. This work provides a useful information for the SP photocatalytic degradation via PDS activation.

Emerging Hybrid Nanocomposite Photocatalysts for the Degradation of Antibiotics: Insights into Their Designs and Mechanisms

The raising occurrence of antibiotics in the global water bodies has received the emerging concern due to their potential threats of generating the antibiotic-resistive and genotoxic effects into humans and aquatic species. In this direction, the solar energy assisted photocatalytic technique offers a promising solution to address such emerging concern and paves ways for the complete degradation of antibiotics with the generation of less or non-toxic by-products. Particularly, the designing of hybrid photocatalyticcomposite materials has been found to show higher antibiotics degradation efficiencies. As the hybrid photocatalysts are found as the systems with ideal characteristic properties such as superior structural, surface and interfacial properties, they offer enhanced photoabsorbance, charge-separation, -transfer, redox properties, photostability and easy recovery. In this context, this review study presents an overview on the recent developments in the designing of various hybrid photocatalytic systems and their efficiency towards the degradation of various emerging antibiotic pharmaceutical contaminants in water environments.