Enhanced synchronous photocatalytic 4-chlorophenol degradation and Cr(VI) reduction by novel magnetic separable visible-light-driven Z-scheme CoFe2O4/P-doped BiOBr heterojunction nanocomposites

Construction of Dual Electric Field Synergistic and Magnetic Recyclable SnFe2O4/ZnO Photocatalyst

The recombination of photoinduced carriers hampers the photocatalysis process. Construction of the heterojunction and built-in piezoelectric field boosts the separation of electrons and holes. Herein, a novel magnetic recyclable SnFe2O4(SFO)/ZnO composite with enhanced photocatalytic performance based on the dual electric field synergism was proposed for the first time. This composite apparently alleviates the carrier recombination in SFO and extends the absorption spectrum of ZnO to the full spectrum. Consequently, 20%SFO/ZnO exhibits an excellent efficiency, which is 2.45 times that of ZnO and 4.61 times that of SFO, respectively. The differences in size and morphology between the SFO nanoparticles and the ZnO nanorods provide more contact areas, thus enlarging the deformation and enhancing the piezoelectric effect. The heterojunction and the piezoelectric field work together to modulate the transferring of carriers and elevate the photocatalytic activity. This design offers a plausible avenue for preparing efficient recyclable photocatalysts for application.

Bi-functional NiFe2O4/SrTiO3 S-scheme heterojunction for eminent performance photocatalytic treatment of sewage effluent and electrochemical hydrazine determination

Devising of materials that afforded dual applicability in decontamination and pollutant detection were still a towering challenge owing to the increasing flux of discharge toxic contaminants over the years. Herein, the NiFe2O4 nanoparticles-loaded on cube-like SrTiO3 (NiFe2O4/SrTiO3) composite was fabricated by a two-step hydrothermal approach providing remarkable photocatalytic treatment and electrochemical sensing of noxious pollutants in wastewater. The material traits of the fabricated composite were scrutinized by myriad characterization approaches. The NiFe2O4/SrTiO3 hybrid material demonstrated high surface area of 19.81 m2/g, adequate band gap energy of 2.75 eV, and prominent photoluminescence characteristics. In the presence of visible light, the NiFe2O4/SrTiO3 exhibited profound photocatalysis capability to eliminate sewage effluent-bearing chlortetracycline hydrochloride (CTCH) with 88.6% COD removal in 120 min, outperforming other pure materials. Meanwhile, the toxicity examination of effluent, the possible degradation pathway of CTCH and the proposed photocatalysis mechanism were also divulged. More importantly, the glassy carbon electrode was modified with synergized NiFe2O4/SrTiO3 (NiFe2O4/SrTiO3-GCE) was adopted for the precise quantification of Hydrazine (Hz). The NiFe2O4/SrTiO3-GCE obeyed first-order response for the Hz detection within the range of 1-10 mM: cyclic voltametric: limit of detection (LOD) of 0.119 μM with sensitivity of 18.9 μA μM-1 cm-2, and linear sweep voltametric: LOD of 0.222 μM with a sensitivity of 12.05 μA μM-1 cm-2. The stability and interference of modified electrode were also inspected. This work furnished valuable insights to yield a composite with the prominent S-scheme heterojunction system for quenching of charge carrier recombination and consequently contributing to the future realization into the domains of environmental clean-up and toxic chemical detection.

High Efficiency Removal Performance of Tetracycline by Magnetic CoFe2O4/NaBiO3 Photocatalytic Synergistic Persulfate Technology

The widespread environmental contamination resulting from the misuse of tetracycline antibiotics (TCs) has garnered significant attention and study by scholars. Photocatalytic technology is one of the environmentally friendly advanced oxidation processes (AOPs) that can effectively solve the problem of residue of TCs in the water environment. This study involved the synthesis of the heterogeneous magnetic photocatalytic material of CoFe2O4/NaBiO3 via the solvothermal method, and it was characterized using different characterization techniques. Then, the photocatalytic system under visible light (Vis) was coupled with peroxymonosulfate (PMS) to explore the performance and mechanism of degradation of tetracycline hydrochloride (TCH) in the wastewater. The characterization results revealed that CoFe2O4/NaBiO3 effectively alleviated the agglomeration phenomenon of CoFe2O4 particles, increased the specific surface area, effectively narrowed the band gap, expanded the visible light absorption spectrum, and inhibited recombination of photogenerated electron-hole pairs. In the Vis+CoFe2O4/NaBiO3+PMS system, CoFe2O4/NaBiO3 effectively activated PMS to produce hydroxyl radicals (·OH) and sulfate radicals (SO4-). Under the conditions of a TCH concentration of 10 mg/L-1, a catalyst concentration of 1 g/L-1 and a PMS concentration of 100 mg/L-1, the degradation efficiency of TCH reached 94% after 100 min illumination. The degradation of TCH was enhanced with the increase in the CoFe2O4/NaBiO3 and PMS dosage. The solution pH and organic matter had a significant impact on TCH degradation. Notably, the TCH degradation efficiency decreased inversely with increasing values of these parameters. The quenching experiments indicated that the free radicals contributing to the Vis+CoFe2O4/NaBiO3+PMS system were ·OH followed by SO4-, hole (h+), and the superoxide radical (O2-). The main mechanism of PMS was based on the cycle of Co3+ and Co2+, as well as Fe3+ and Fe2+. The cyclic tests and characterization by XRD and FT-IR revealed that CoFe2O4/NaBiO3 had good degradation stability. The experimental findings can serve as a reference for the complete removal of antibiotics from wastewater.

Abatement of microbes and organic pollutants using heterostructural nanocomposites of rice straw CQDs with substituted strontium ferrite

Sustainable use of agricultural waste still remains a challenging task. Herein, we used rice straw as a carbon precursor to prepare carbon quantum dots (CQDs) for photocatalytic applications. Nanocomposites of CQDs with Ti4+ and Mg2+ substituted strontium ferrite (Sr0·4Ti0·4Mg0·2Fe2O4.4) nanoparticles (NPs) in varying w:w ratio was synthesized by ultrasonication method. The successful formation of nanocomposites was confirmed by various microscopic and spectroscopic techniques. The photocatalytic and antibacterial activity of NPs, CQDs and nanocomposites was comparatively evaluated using tetracycline hydrochloride, azure B, Staphylococcus aureus and Escherichia coli as model pollutants. The CQDs-Sr0.4Ti0·4Mg0·2Fe2O4.4 nanocomposite with a w:w ratio of 2:1 showed excellent photocatalytic and antibacterial activity, with the degradation and inactivation efficiency ranging from 97.1% to 99.0% in presence of visible light. The increased specific surface area (117.2 m2/g), and reduction in band gap (2.48 eV-2.09 eV) and decreased photoluminescence intensity of nanocomposites all corroborated these results. The impacting experimental parameters such as catalyst dose, pH and contact time were also examined. Quenching experiments confirmed that hydroxyl radicals (HO∙) radicals and holes (h+) played a vital role in the degradation of pollutants. The kinetics of photodegradation was explained by using the Langmuir-Hinshelwood model. Box-Behnken statistical modelling was used to optimize photocatalytic parameters. Results indicated that the nanocomposite of CQDs with Sr0·4Ti0·4Mg0·2Fe2O4.4 can serve as a promising photocatalyst for the removal of pollutants and microbes.

Strategies to attenuate ciprofloxacin inhibition on enhanced biological phosphorus removal from wastewater and its recoverability

The inhibiting effects of ciprofloxacin (CIP) on enhanced biological phosphorus removal (EBPR) were investigated with no change in reactor operation and with increased aeration rate and sludge retention time (SRT) to explore inhibition-alleviating solutions. Additionally, performance recoverability was evaluated. The results showed that the phosphorus removal efficiency in the presence of 0.002-0.092 mg/L CIP for 7 days was only 12.5%. Increasing the aeration rate relieved inhibition (33.5% phosphorus removal efficiency on Day 7), and increasing SRT slowed EBPR performance deterioration. The EBPR performance recovered from CIP inhibition and increases in the aeration rate and SRT resulted in different recovery phenomena. The maximum PO43--P release rate continued to decrease in the first 2 days of the recovery stage and then gradually increased. However, the maximum PO43--P uptake rate immediately increased at different rates among reactors, which might be attributed to variations in the microbial community structure, decreased poly-P content, and enhanced abundances of ABC transporters and quorum sensing. It was found that some microorganisms associated with phosphorus removal were more tolerant to CIP than glycogen accumulating organisms. Moreover, the increased relative abundance of the qepA gene indicated that the microorganisms in the EBPR system had strong antibiotic resistance capacity. The bacterial community structure was significantly affected by CIP and could not recover to the initial structure. The results help to provide technical support for the operation of the EBPR process in the presence of CIP and to increase the understanding of system recoverability.

Designing Z-scheme In2O3 @ZnIn2S4 core-shell heterojunctions for enhanced photocatalytic multi-pollutant removal

In water bodies, the coexistence of and interaction between multiple pollutants complicate remediation. In this study, the In2O3 @ZnIn2S4 Z-scheme heterojunction with a stratified core-shell structure was constructed and used to remove multiple pollutants (tetracycline hydrochloride and Cr(VI)). The large number of active sites and the mechanism of photogenerated charge separation ensured the substantially enhanced catalytic activity of this photocatalyst, making it superior to In2O3 nanospheres and pure ZnIn2S4. The optimised In2O3 @ZnIn2S4 nano-flowers (In2O3 @ZnIn2S4 NFs) realised 99.8% removal of tetracycline hydrochloride and 100% removal of Cr(VI) within 60 min under visible-light. The material's high stability was demonstrated by five experiment cycles. Effects of organics, inorganics, and pH about the photocatalytic performance of the optimised In2O3 @ZnIn2S4 NFs when tetracycline hydrochloride and Cr(VI) coexist were also explored. Finally, the intermediates and degradation pathways were analysed, and the possible photocatalytic mechanism was also investigated by performing density functional theory calculations.

The activation mechanism of peroxymonosulfate and peroxydisulfate by modified hydrochar: Based on the multiple active sites formed by N and Fe

Modified hydrochar (NHC@Fe), with multiple functional groups and transition metal oxide-containing surface, was successfully synthesized by one-step hydrothermal method. The differences in its catalytic activity for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation were studied in detail. Experimental and DFT studies showed that abundant active sites, namely, transition metals and functional groups on NHC@Fe provided multiple effective pathways for the activation of persulfate (PS). The NHC@Fe/PMS and NHC@Fe/PDS systems could degrade about 80% of tetracycline hydrochloride (TC) in 120 min and were found to be better than those modified by iron or nitrogen alone. This emphasized the advantage of N-Fe co-modification in persulfate activation. Although the Fe2+/Fe3+ cycle accelerated the activation, the activation of PMS mainly relied on Fe3+, whereas that of PDS mainly relied on Fe2+. Moreover, Fe-N, pyrrolic N, pyridine N, C-O, and O-CO groups also played a key role in the activation process, but the dominant action sites were not the same. Multiple free radicals, such as SO4•-, •OH, O2•-, and 1O2 were generated in PMS and PDS activation systems. 1O2 induced non-free radical pathway was mainly involved in the degradation of TC in both activation systems, but the generation pathway of 1O2 was more direct and rapid in the PDS system. This study provides detailed DFT models of the active sites activated by PMS and PDS and discusses the activation pathways of PMS and PDS along with the similarities and differences in ROS reaction mechanisms.

Interface engineering of 0D/2D Cu2O/BiOBr Z-scheme heterojunction for efficient degradation of sulfamethoxazole: Mechanism, degradation pathway, and DFT calculation

Constructed heterojunction has been considered an efficient strategy to enhance the migration and transfer of photoinduced charge carriers. Herein, a Z-scheme Cu2O/BiOBr heterojunction with 0D/2D structure was fabricated by microwave hydrothermal method. It was found that the optimal composites photocatalyst showed excellent activity for sulfamethoxazole (SMZ) illumination, and the removal rate reached 90.7%, which was higher than pristine Cu2O (53.0%) and BiOBr (60.0%). Subsequently, the operational parameters such as catalyst dosage, concentrations of pollutants, and pH of solution were investigated. According to the ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRs), Mott-Schottky curve, and density functional theory (DFT) analysis, the Z-scheme degradation mechanism of Cu2O/BiOBr heterostructure was proposed. Among them, the interface structure of 0-dimensions/2-dimensions (0D/2D) can significantly increase the number of heterojunctions in the composite catalyst, and Z-scheme heterostructures can accelerate the generation and migration of photoinduced charge carriers, which has a facilitation effect on improving the decomposition activity of the photocatalyst. Moreover, three possible pathways for SMZ degradation were inferred. This study provides a promising strategy for constructing novel heterojunctions with high photocatalytic performance.

Eminent destruction of organics and pathogens concomitant with power generation in a visible light-responsive photocatalytic fuel cell with NiFe2O4/ZnO pine tree-like photoanode and CuO/Cu2O nanorod cathode

Environmental conservation and energy scarcity have become two core challenges with the ever-increasing advancement of industry, particularly chemical energy rich wastewater comprising refractory organics and pathogenic microbes. Here, a multifunctional photocatalytic fuel cell (PFC) was devised using NiFe2O4 nanoparticle-loaded on pine tree-like ZnO/Zn (NiFe2O4/ZnO/Zn) photoanode and CuO/Cu2O nanorods-loaded on Cu (CuO/Cu2O/Cu) cathode for extracting electricity upon wastewater treatment. When fed with Rhodamine B (RhB) dyestuff, the NiFe2O4/ZnO/Zn-PFC provided the maximum power density (Pmax) of 0.539 mW cm-2 upon visible light irradiation with an average RhB degradation of 85.2%, which were 2.8 and 2.7 times higher than ZnO/Zn, respectively. The remarkable enhanced NiFe2O4/ZnO/Zn-PFC performance was owing to the synergistic effect of pine tree-like structure and Z-scheme heterostructure. The pine tree-like with high surface area was not only for effective harnessing photon energies but also provided more directional routes for rapid segregation and transport of carriers and higher interface contacting areas with electrolyte. Through a series of systematic characterizations, the Z-scheme heterostructure mechanism of the system and organics degradation pathway were also speculated. Additionally, the performance of the NiFe2O4/ZnO/Zn-PFC in industry printing wastewater showed Pmax of 0.600 mW cm-2, which was considerably impressive as real wastewater was challenging to accomplish. The phytotoxicity outcome also manifested that the comprehensive toxicity of RhB was eradicated after PFC treatment. Lastly, the excellent recyclability and the pronounced bactericidal effect towards Escherichia coli and Staphylococcus aureus were other attributions which enabled the NiFe2O4/ZnO/Zn-PFC for possible practical application.

A Fresh Perspective on the Impact of ZnTiO3 Coupling on the Microstructure and Photocatalytic Properties of TiO2 Fabricated at Varied Temperatures

ZnTiO3/TiO2 composite photocatalysts were synthesized via the sol-gel technique, and the impact of varying heat treatment temperatures (470, 570, 670 °C) on their crystalline arrangement, surface morphology, elemental composition, chemical state, specific surface area, optical characteristics, and photocatalytic efficacy was systematically investigated. The outcomes revealed that, as the temperature ascends, pure TiO2 undergoes a transition from anatase to rutile, ultimately forming a hybrid crystal structure at 670 °C. The incorporation of ZnTiO3 engenders a reduction in the TiO2 grain dimensions and retards the anatase-to-rutile phase transition. Consequently, the specimens manifest a composite constitution of anatase and ZnTiO3. In contrast, for pure TiO2, the specimen subjected to 670 °C annealing demonstrates superior photocatalytic performance due to its amalgamated crystal arrangement. The degradation efficacy of methylene blue (MB) aqueous solution attains 91% within a 60-min interval, with a calculated first-order reaction rate constant of 0.039 min-1. Interestingly, the ZnTiO3/TiO2 composite photocatalysts exhibit diminished photocatalytic activity in comparison to pristine TiO2 across all three temperature variations. Elucidation of the photocatalytic mechanism underscores that ZnTiO3 coupling augments the generation of photogenerated charge carriers. Nonetheless, concurrently, it undermines the crystalline integrity of the composite, yielding an excess of amorphous constituents that impede the mobility of photoinduced carriers. This dual effect also fosters escalated recombination of photogenerated charges, culminating in diminished quantum efficiency and reduced photocatalytic performance.

Fe3O4/CuO/Chitosan Nanocomposites: An Ultrasound-Assisted Green Approach for Antibacterial and Photocatalytic Properties

The fundamental goal of this research was to use an environmentally friendly sonochemical method to synthesize a Fe3O4/CuO/chitosan magnetic nanocomposite. The nanocomposites featured particle sizes ranging from 50 to 90 nm, and structural characteristics were thoroughly examined. Moreover, the material displayed selective photodegradation capabilities with MB, achieving an impressive efficiency of nearly 98% within 180 min under specific conditions. Notably, the material's reusability was remarkable, maintaining an efficiency of approximately 88% even after five cycles. The possible photodegradation mechanism was proposed based on the evaluation of energy bands, along with a comprehensive analysis of the impacts on MB photodegradation. Concurrently, adsorption isotherms and kinetic models were evaluated. Additionally, this material exhibited promising antibacterial activity against Saccharomyces cerevisiae, Bacillus subtilis, and Escherichia coli. These findings suggested that the Fe3O4/CuO/chitosan material could be utilized in real-world scenarios for environmental purification due to its ability to function as a photocatalyst and antibacterial agent.

Metal ion endogenous cycles of CoFe2O4-x induced boosted photocatalytic/PMS degradation toward polycyclic aromatic hydrocarbons

The rational design of photocatalytic nanomaterials with unique structures is critical for remediating environmental problems and thus reducing ecological risks. In this work, we employed H₂ temperature-programmed reduction to modify MFe₂O₄ (M = Co, Cu, and Zn) photocatalysts for obtaining additional oxygen vacancies. After activation of PMS, naphthalene and phenanthrene degradation rates in the soil phase were increased by 3.24-fold and 1.39-fold, respectively, and 1.38-fold for naphthalene in the aqueous phase by H-CoFe₂O_4-x. The extraordinary photocatalytic activity is attributed to the oxygen vacancies on the H-CoFe₂O_4-x surface, which promote electron transfer and thus enhance the redox cycle from Co(III)/Fe(III) to Co(II)/Fe(II). In addition, oxygen vacancies are used as electron traps to hinder the recombination of photogenerated carriers and accelerate the generation of hydroxyl and superoxide radicals. Quenching tests showed that the addition of p-benzoquinone resulted in the greatest decrease in the degradation rate of naphthalene (inhibition of about 85.5%), demonstrating that O₂˙^- radicals are the main active species in the photocatalytic degradation of naphthalene. H-CoFe₂O_4-x showed improved degradation performance in synergy with PMS (82.0%, k_app = 0.00714 min^-1) while maintaining excellent stability and reusability. Hence, this work provides a promising approach for the design of efficient photocatalysts to degrade persistent organic pollutants in soil and aqueous environments.

Comparative Evaluation of Bioefficiency and Photocatalytic Activity of Green Synthesized Bismuth Oxide Nanoparticles Using Three Different Leaf Extracts

Nanotechnology has emerged as a promising method for wastewater recycling. In this line, the current study emphasizes the leaf-extract-mediated biosynthesis of bismuth oxide nanostructures (BiONPs) using three different plants, namely Coldenia procumbens Linn (Creeping Coldenia), Citrus limon (Lemon), and Murraya koenigii (Curry) through a greener approach and evaluates their biological properties as well as photocatalytic performance for the first time. As-synthesized BiONPs were physiochemically characterized using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray analysis (EDAX). Using the well diffusion method, research on the antibacterial efficiency of BiONPs against human pathogenic Gram-positive bacteria, such as Staphylococcus aureus and Enterococcus faecalis, and Gram-negative bacteria, including Escherichia coli and Klebsiella pneumonia, revealed that Gram-negative bacteria exhibited relatively strong activity. The larvicidal activity assessed against Aedes aegypti and Aedes albopictus mosquito larvae reveals promising larvicidal activity with a minimal dosage of BiONPs with LC₅₀ values of 5.53 and 19.24 ppm, respectively, after 24 h of exposure. The excellent photocatalytic activity of as-synthesized BiONPs was demonstrated through the photodegradation of malachite green (MG) and methylene blue (MB) dyes with respective degradation performance parameters of 70 and 90%. The biogenic synthetic approach reported here enables the scalable commercial synthesis of bismuth nanostructures for their widespread use in catalysis for wastewater treatment and environmental cleanup.

Waste-Extracted Zn and Ag Co-Doped Spent Catalyst-Extracted V2O5 for Photocatalytic Degradation of Congo Red Dye: Effect of Metal-Nonmetal Co-Doping

The current study applies the eco-friendly principle of “wastes treat wastes”. By swift methods, a composite photocatalyst was prepared from waste-extracted oxides, namely V2O5, Ag, and ZnO. The metal–lixiviant complexes were used as metal precursors, where the lixiviants act as auto-templates and increase the compatibility between the mixed metallic species, and their controlled thermal removal generates pores. The tri-constitute composite catalyst was doped with nitrogen. The constitution, surface composition, and optical properties of the doped catalysts were investigated by XRD, SEM, TEM, BET surface analysis, XPS, diffuse reflectance, and PL spectra. The as-prepared catalysts were employed in the photodegradation of Congo red dye (CR) under visible irradiation at ambient temperature. The degree of Ag dispersion had a significant effect on the bandgap, as did metal and metal-nonmetal co-doping. The efficiency of dye removal changes dramatically with time up to 120 min, after which it begins to decrease. According to the pH effect, the normal pH of Congo red dye (6.12) is optimal. At a catalyst dose of 1 g L−1 and an irradiation period of 120 min, photodegradation efficiency reached 89.9% and 83.4% over [Ag0.05 ZnO0.05 V2O5(0.90)] and [Ag0.05 ZnO0.05 V2O5(0.90)]N, respectively. The kinetic study depicted the significant role of mass transfer in the reaction rate. The obtained rate constants were 0.995 mole L−1 S−1 and 0.998 mole L−1 S−1 for [Ag0.05 ZnO0.05 V2O5(0.90)] and [Ag0.05 ZnO0.05 V2O5(0.90)]N, respectively.

Photocatalysis of carbamazepine via activating bisulfite by ultraviolet: Performance, transformation mechanism, and residual toxicity assessment of intermediates products

Carbamazepine (CBZ) as an extensively distributed emerging pollutant has menaced ecological security. The degradation performance of CBZ by UV driven bisulfite process was investigated in this work. The kinetics results indicated that CBZ was high-efficiently degraded by UV/bisulfite following a pseudo first-order kinetic model (K_obs = 0.0925 min^-1). SO₄^•- and •OH were verified as the reactive oxidants by EPR test and the radicals scavenging experiment using MeOH and TBA. SO₄^•- played a dominant role for CBZ degradation. The Density functional theory (DFT) and LC-qTOF-MS/MS clarified that hydroxylation, ketonation, ring opening reaction, and ring contraction were main transformation patterns of CBZ. As to influence factors, CBZ degradation was significantly hindered in presence of CO₃^2-, HPO₄^2- and NOM. Toxicological analysis derived from metabonomics suggested that the remarkable alteration of metabolic profile was triggered by exposure to intermediates mixture. CBZ intermediates interfered in several key metabolic pathways, including pentose phosphate, amino acids, lysine degradation, glycerophospholipid, glutathione, nucleotides and carbohydrate, which was alleviated after UV/bisulfite treatment. This work provided a meaningful support to potential risk of CBZ intermediates products, which shed light on the future application in eliminating drugs using UV /bisulfite.

Interfacial engineering of novel inorganic-organic β-Ga2O3/COF heterojunction for accelerated charge transfer towards artificial photosynthesis

Semiconductor-based solar-driven CO₂ to fuels has been widely reckoned as an ingenious approach to tackle energy crisis and climate change simultaneously. However, the high carrier recombination rate of the photocatalyst severely dampens their photocatalytic uses. Herein, an inorganic-organic heterojunction was constructed by in-situ growing a dioxin-linked covalent organic framework (COF) on the surface of rod-shaped β-Ga₂O₃ for solar-driven CO₂ to fuel. This novel heterojunction is featured with an ultra-narrow bandgap COF-318 (absorption edge = 760 nm), which is beneficial for fully utilizing the visible light spectrum, and a wide bandgap β-Ga₂O₃ (absorption edge = 280 nm) to directional conduct electrons from COF to reduce CO₂ without electron-hole recombination occurred. Results showed that the solar to fuels performance over β-Ga₂O₃/COF was much superb than that of COF. The optimized Ga₂O₃/COF achieved an outstanding CO evolution rate of 85.8 μmol h^-1·g^-1 without the need of any sacrificial agent or cocatalyst, which was 15.6 times more efficient than COF. Moreover, the analyses of photoluminescence electrochemical characterizations and density functional theory (DFT) calculations revealed that the fascinate construction of β-Ga₂O₃/COF heterojunction significantly favored charge separation and the directional transfer of photogenerated electrons from COF to β-Ga₂O₃ followed by CO₂. This study paves the way for developing effective COF-based semiconductor photocatalysts for solar-to-fuel conversion.

Improved Cr (VI) adsorption performance in wastewater and groundwater by synthesized magnetic adsorbent derived from Fe3O4 loaded corn straw biochar

This work developed an easy method to utilize corn straw (CS) waste for sustainable development and reduce the volume of waste volume as well as bring value-added. The magnetic adsorbent was prepared by loading Fe₃O₄ onto biochar derived from corn straw (Fe@CSBC), then used for capturing Cr (VI) in groundwater and wastewater samples. The characterization of adsorbents showed that Fe3O4 was successfully loaded on corn straw biochar (CSBC) and contributed to the improvement of the surface area, and surface functional groups like Fe-O, Fe-OOH, CO, and O-H. The presence of iron oxide was further confirmed by XPS and XRD analysis and a magnetization value of 35.6 emu/g was obtained for Fe@CSBC. The highest uptake capacity of Cr (VI) onto Fe@CSBC and CSBC by monolayer were 138.8 and 90.6 mg/g, respectively. By applying magnetic adsorbent Fe@CSBC for the treatment of groundwater and wastewater samples, the chromium could be removed up to 90.3 and 72.6%, respectively. The remaining efficiency of Cr (VI) was found to be 84.5% after four times reused Fe@CSBC, demonstrating the great recyclable ability of the adsorbent. In addition, several interactions between Cr (VI) and Fe@CSBC like ion exchange, complexation, and reduction reaction were discussed in the proposed adsorption mechanism. This study brings an efficient method to turn corn straw biomass into an effective magnetic adsorbent with high adsorption performance and good reusability of Cr (VI) in groundwater as well as in wastewater.

Enhanced Photocatalytic Degradation of P-Chlorophenol by ZnIn2S4 Nanoflowers Modified with Carbon Quantum Dots

The removal of chlorophenol (CP) contaminants from water is a great challenge owing to their natural robustness and the toxic chlorinated by-products generated in degradation processes. In this work, a series of three-dimensional nanoflower-like structured photocatalysts (CQDs/ZnIn2S4-x, x = 1, 2, or 3 wt%) were fabricated via a facile hydrothermal approach. Excellent photocatalytic abilities toward 4-CP degradation under Xe lamp irradiation were achieved over the as-prepared composites. The removal efficiency of total organic carbon for 4-CP on the optimized CQDs/ZnIn2S4-2 was 49.1%, which was 16.0% higher than that of ZnIn2S4. The presence of CQDs could not only be used to adjust controllable band structures for enhancing light absorption, but it could also serve as an electron acceptor to promote the transition of electron–hole pairs. Moreover, a possible degradation mechanism of 4-CP was also proposed according to the analyses of active species, electron paramagnetic resonance characterization, degradation products, and attacked sites. Overall, this work unveils a superior function of an efficient photocatalyst for refractory organic pollutants.