Degradation Efficiency Of Methyl Orange Research Articles

Elimination of synthetic dyes by clamshell derived photo-active hydroxyapatite

Herein, a novel designed hydroxyapatite (HAp) derived from freshly calcined clamshell waste through the wet precipitation method was synthesized. HAp has been developed as a heterogeneous photocatalyst for the anionic dye methyl orange (MO) degradation. The pH on synthesizing HAp was varied in basic conditions. The results show HAp formed at pH more than 10. The MO photodegradation was done under UV-light irradiation for 120 min. HAp catalyst showed the optimum MO degradation efficiency using rod-like structure HAp synthesized at pH 12. HAp with optimum photodegradation efficiency was optimized for the catalyst loading and the pH of the MO solution. MO at pH 6 with 0.05 g catalyst loading showed the highest degradation efficiency around 97 % using HAp prepared at pH 12 with band gap at 4.990 eV. This finding brings a new insight on natural sources materials as photo-active in sustainable of persistent water pollutants.

Bimetal Cu/Ni-BTC@SiO2 metal-organic framework as high performance photocatalyst for degradation of azo dyes under visible light irradiation

There has been significant attention on the efficient degradation of pollutants in wastewater using metal-organic frameworks (MOFs) photocatalytic methods over the past decade. Herein, we examined the elimination of two different types of water-contaminating dyes, specifically cationic dye methylene blue (MB) and anionic dye methyl orange (MO), through the application of bimetal Cu/Ni-BTC@SiO2 MOF as high performance photocatalyst. The bimetal Cu/Ni-BTC@SiO2 photocatalyst was synthesized and characterized by XRD, FTIR, SEM, TEM, TGA, BET, DRS, and VSM techniques. The examination of the impact of different operational factors on the elimination of pollutants involved a comprehensive analysis of variables including the photocatalyst type, initial pollutant concentration, quantity of photocatalyst, and pH levels. The highest removal efficiency for MO and MB dyes by the photocatalyst was found to be 98 and 71%, respectively, within 60 min. In the fifth reaction stage, degradation efficiency for MO and MB was 76 and 56% respectively. Kinetic investigations demonstrated that, in the context of the uptake of MB and MO dyes, the interparticle diffusion, and pseudo-second-order models emerged as possessing the most robust correlation coefficients with the experimental data, registering values of 0.988 and 0.961, respectively. The examination of isotherms reveals that the isotherm models proposed by BET, and Anderson (V) demonstrate the highest level of conformity with the empirical data for the decomposition of MB and MO dyes, correspondingly. The TOC levels decreased significantly from 51 to 14 and 47 to 3 mg/L for MB and MO dyes, indicating the effective mineralization process using Cu/Ni-BTC@SiO2.

Cellulose-based materials in tailoring a novel defective titanium‑carbon‑phosphorus hybrid composites for highly efficient photocatalytic activity

Until now, black titania has attracted much interest as a potential photocatalyst. In this contribution, we report the first demonstration of the effective strategy to fundamentally improve the photocatalytic performance using a novel sustainable defective titanium‑carbon-phosphorous (TCPH) hybrid nanocomposite. The prepared TCPH was used for photocatalytic degradation of the main organic pollutants, which is methyl orange (MO) dye. The physico-chemical properties of as-prepared samples were characterized by various techniques to observe the transformations after carbonization and the interaction between different composite phases. The existence of Ti+3 and oxygen vacancies at the surface, and a notable increase in surface area, are all demonstrated by TCPH, together with the distinct core-shell structure. These unique properties exhibit excellent photocatalytic performance due to the boosted charge transport and separation. The highest degradation efficiency of methyl orange (MO) was attained in the case of TCPH when compared with titanium-cellulose-phosphorous (TCeP) and titanium‑carbon-phosphorous (TCPN). Accordingly, the highest degradation efficiency was achieved by applying the optimal operational conditions of 1 g/L of TCPH catalyst, 10 mg/L of MO, pH of 7 and the temperature at 25 ± 3 °C after 3 min under LED lamp (365 nm) with light intensity 100 mW/cm2. The degradation mechanism was investigated, and the trapping tests showed the dominance of hydroxyl radicals in the degradation of MO. TCPH showed high stability under a long period of operation in five consecutive cycles, which renders the highly promising on an industrial scale. The fabrication of highly active defective titanium‑carbon-phosphorous opens new opportunities in various areas, including water splitting, and CO2 reduction.

Preparation and Spectrochemical characterization of Ni-doped ZnS nanocomposite for effective removal of emerging contaminants and hydrogen Production: Reaction Kinetics, mechanistic insights

In this study, we report the successful synthesis of Ni-doped ZnS nanocomposite via a green route using ethanolic crude extract of Avena fatua. The as-synthesized nanocomposite was comprehensively characterized using Dynamic light scattering (DLS), Zeta potential, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). These analyses provided detailed insights into the size, morphology, composition, surface properties, and structural characteristics of the nanocomposite. Subsequently, the synthesized nanocomposite was evaluated for their photocatalytic performance against the organic dye Methyl orange. Remarkably, the nanocomposite exhibited rapid and efficient degradation of Methyl orange, achieving 90 % degradation within only 30 min of irradiation under UV light. Moreover, the photocatalyst demonstrated an exceptional hydrogen production rate, reaching 167.73 µmolg-1h−1, which is approximately 4.5 times higher than that of its pristine counterparts. These findings highlight the significant potential of Ni-doped ZnS nanocomposite as highly efficient photocatalysts for wastewater treatment and hydrogen production applications.

Improved photocatalytic performance of Sn/Cl co-doped TiO2 nanoparticles via a novel volatilization solid solution method

Sn/Cl co-doped TiO2 nanoparticles were synthesized via a novel volatile solid solution method. The effect of SnCl2·2H2O concentration (0–35.4 mol.%) and calcination temperature on thermal effect, crystal structure, morphology, composition, light absorption and photocatalytic performance of TiO2 nanoparticles was investigated by TG-DSC, XRD, SEM, EDS, TEM, HRTEM, SAED, UV–Vis, PL, photocurrent test, EIS and XPS. Results indicate that Sn and Cl are co-doped into TiO2 crystal lattice forming a mixed anatase-rutile TiO2 phase without SnO2 phase when SnCl2·2H2O concentration is below 17.7 mol.%, and excess SnCl2·2H2O caused the rutile SnO2 generation and simultaneous rutile TiO2 disappearance. The degradation efficiency of methyl orange reaches 98.7 % using 17.7 mol.% SnCl2·2H2O modified TiO2 calcined at 380 °C after 2 h of 15 W UV light irradiation, which is 19.72 % and increases by two times compared with that of pure TiO2 (8.98 %) after 2 h of 15 W visible light irradiation, both showing the maximum photocatalytic performance possibly due to the simultaneous increased active surface sites, enhanced light absorption and improved separation efficiency of photogenerated electron-hole pairs resulted from small particle size, reduced energy band gap and formation of mixed anatase-rutile TiO2 phases. Reactive species scavenging experiments revealed that O.-2 and h+ play a dominant role in photodegradation process.

Efficient degradation of methyl orange in wastewater via bio‐electro‐Fenton system: optimization, pathway investigation and process evaluation

AbstractBACKGROUNDThe efficient and green technology of dye removal has been widely investigated. In this study, a bio‐electro‐Fenton system was used to degrade methyl orange (MO). For the system optimization, five experimental groups were detected, including pH (1–6), iron (Fe2+) concentration (3–15 mmol L−1), airflow rate (0–20 mL min−1), external voltages (0.2–1.0 V) and initial MO concentration (20–100 mg L−1).RESULTSOptimal conditions of pH 3, Fe2+ concentration 9 mmol L−1, air flowrate 12 mL min−1, external voltage of 0.6 V and MO concentration 60 mg L−1 were selected, resulting in a 92% efficiency. For the pathway investigation of MO degradation, under oxidization by ˙OH, demethylation, broken azo bonds and broken benzene ring structure were obtained. Intermediate products were predicted. For the system evaluation, energy consumption of 0.15–0.59 KWh was determined for 1 m3 MO wastewater. The total cost of degrading MO wastewater could decrease to US$470.0 m−3 by adjusting operational time.CONCLUSIONConsidering the Fe2+ regeneration and the low energy consumption, this bio‐electro‐Fenton system can be considered as one of the most environmentally‐friendly approaches for MO degradation; however, quantitative evaluation on sustainability needs to be further discussed via advanced assessment tools (such as life‐cycle assessment). © 2024 Society of Chemical Industry (SCI).

Photocatalytic Activity and Self-Cleaning Effect of Coating Mortars with TiO2 Added: Practical Cases in Warm Sub-Humid Climates.

In this study, the photocatalytic activity of coating mortars with synthetized and commercial TiO2 nanoparticles added has been evaluated at 2, 3 and 5% by weight of cement by calculating the degradation efficiency of methyl orange and red wine dyes exposed to both visible-light and UV radiation; also, the self-cleaning effect of coatings exposed to weather conditions (warm sub-humid climate) was assessed. TiO2 nanoparticles were synthesized via the sol-gel method to a low synthesis temperature and characterized via X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The results show synthesized TiO2 particles in anatase phase with a crystallite size of 14.69 nm, and hemispherical particles with sizes of submicron order. The addition percentage with the best performance in the coating mortars was 3%, with both commercial and synthesized TiO2; however, coating mortars with synthesized TiO2 exhibited the highest degradation efficiency for both dyes when they were exposed to visible light, while mortars with commercial TiO2 exhibited the highest degradation efficiency when exposed to UV radiation. In addition, in coating mortars with synthesized TiO2, the self-cleaning effect was evident from the beginning of exposure to weather, reaching the largest dye-free surface at the end of exposure. The compressive strength increased significantly in mortars with TiO2 addition.

Insights into the photocatalytic role of glycine-assisted sol-gel auto-combustion synthesized (Co, Mn)(Co, Mn)2O4 nanostructures for efficient visible light-driven degradation of methyl orange

Research on the use of new materials and the improvement of existing fast ways for removal of water pollutants is still challenging. This work documented rational fabrication of (Co, Mn)(Co, Mn)2O4 nanoparticles as nano-photocatalyst materials with improved charge carrier separation and strong redox potential for efficient degradation of methyl orange (MO) in wastewater. This investigation illustrated that the Co/Mn molar ratio can greatly affect the textural and structural properties. From the point of view of size and shape, the optimum product with 1:3 M ratio of Co to Mn precursors was selected as a catalyst in the photocatalysis process. The prepared highly crystallized phase of tetragonal (Co, Mn)(Co, Mn)2O4 describe an optical band gap of 1.7 eV, according to the DRS data, which make them as efficient visible driven photocatalysts. The photodegradation experiments of spinel mixed structures were assessed by investigation of photocatalyst dosages and initial MO concentrations to unravel how these operational parameters affect Co-Mn-O photocatalysis. A remarkable discoloration capability of 68.07 % could result from the catalyst dosage of 0.04 g and dye concentration of 15 mg/L after 120 min of visible light. The kinetics survey further unveiled the maximum rate constant of 0.0080 min−1 for the MO degradation. In the scavenger trials, singlet oxygen (1O2) and superoxide (●O2−) radicals were principal reactive oxygen species (ROS) responsible for pollutant photodegradation in the presence of pure (Co, Mn)(Co, Mn)2O4 structures. In addition, the cyclic performance of catalyst depicted a removal efficiency of 60.1 % over 5 runs.

Facile preparation of ZnO/TiO2 nanocomposite photocatalysts and study of their photocatalytic performance

Due to its strong photocatalytic activity, chemical stability, resistance to chemical and optical corrosion, and non-toxic qualities, TiO2 has received a lot of attention as a significant semiconductor material. One of the main areas of research in the field of photocatalysis has always been the system made of ZnO, another significant semiconductor, which has stronger physical and chemical characteristics and photocatalytic activity than TiO2 and ZnO alone.The performance of the photocatalysts can be optimized by adjusting the ratio of the components in the complexes. It was found that the catalytic activity of the particulate ZnO nano photocatalysts could be improved by trace TiO2 addition and high TiO2 concentration in the complex, with higher degradation efficiency for methyl orange under simulated solar illumination. The enhanced performance was attributed to the high photogenerated electron-hole separation rate caused by the increased surface oxygen vacancy defects and the enhanced interfacial charge transfer of the pluralistic heterojunction structure. In addition, there is a certain selectivity of ZnO and TiO2 for the photocatalytic degradation of methylene blue and methyl orange, which is related to the charged nature of the catalyst surface and the ionic nature of the pollutant molecules. The inhibitor studies revealed that the degradation reactions of methylene blue and methyl orange involved the active species hydroxyl radicals, superoxide radicals, and photogenerated holes formed on the catalyst surface, with superoxide radicals dominating the methyl orange reaction. The produced photocatalysts' great stability was validated by cycling experiments. Further research on the impact of catalyst dosage and pH of the contaminant solution on the photocatalytic performance of the catalysts revealed that an increase in catalyst dosage resulted in a greater number of active sites for contaminant molecules and incident light, which increased the efficiency of contaminant degradation. In an alkaline environment, the efficiency of the catalyst for photodegradation of pollutants was significantly increased due to the high concentration of strongly oxidizing hydroxyl radicals contained in the alkaline solution.

V2C MXene–modified g-C3N4 for enhanced visible-light photocatalytic activity

Increasing the efficiency of charge transfer and separation efficiency of photogenerated carriers are still the main challenges in the field of semiconductor-based photocatalysts. Herein, we synthesized g-C3N4@V2C MXene photocatalyst by modifying g-C3N4 using V2C MXene. The prepared photocatalyst exhibited outstanding photocatalytic performance under visible light. The degradation efficiency of methyl orange by g-C3N4@V2C MXene photocatalyst was as high as 94.5%, which is 1.56 times higher than that by g-C3N4. This was attributed to the V2C MXene inhibiting the rapid recombination of photogenerated carriers and facilitating rapid transfer of photogenerated electrons (e−) from g-C3N4 to MXene. Moreover, g-C3N4@V2C MXene photocatalyst showed good cycling stability. The photocatalytic performance was higher than 85% after three cycles. Experiments to capture free radicals revealed that superoxide radicals (·O2−) are the main contributors to the photocatalytic activity. Thus, the proposed g-C3N4@V2C MXene photocatalyst is a promising visible-light catalyst.

Efficient degradation of methyl orange by heterogeneous Fenton reaction using modified bentonite by a simple method

Efficient degradation of methyl orange by heterogeneous Fenton reaction using modified bentonite by a simple method

Hybrid of carbon quantum dots modified g-C3N4 nanosheets and MoS2 nanospheres: Indirectly promote hydroxyl group production for efficient degradation of methyl orange

Azo dye molecules represented by methyl orange (MO), widely exist in industrial wastewater, and their efficient degradation requires hydroxyl groups with high oxidation activity. g-C3N4/MoS2 heterojunctions are widely used in many photocatalytic applications. However, typical type-II narrow bandgap heterojunctions have holes that cannot be directly oxidized to hydroxyl groups, which is an important barrier to MO degradation. In this work, g-C3N4 nanosheets were modified with carbon quantum dots (CQDs) and combined with spherical MoS2 nanoparticles to form CCN/MS composite photocatalysts. CQDs can be used as electronic reservoir to efficiently separate photogenerated carriers and facilitate the indirect generation of hydroxyl radicals. The results showed that the CCN/MS (10:1) sample had the most excellent degradation performance, with 93 % MO degradation in 120 min, while the control sample of CN/MS (10:1) without introducing CQDs had a degradation rate of only 24 % within the same time interval. In the mixed MO/MB degradation experiments, the degradation of MO was preferred to that of MB, suggesting the existence of a competitive mechanism between the two molecules. Our work proposes a possible pathway for the generation of hydroxyl groups using narrow bandgap semiconductor heterojunction catalysts, which provides a new perspective for understanding the degradation mechanism of pollutant molecules in real industrial wastewater.

Enhanced photocatalytic activity of ZnO microflowers by a trace amount of Ti3C2 MXene

As a novel metal compound with a narrow bandgap and excellent conductivity, two-dimensional (2D) layered Ti3C2 MXene has received growing attention from researchers. In this work, microflower-like ZnO/Ti3C2 composite photocatalysts were prepared by a one-pot method and characterized by XRD, SEM, TEM and XPS techniques. The photocatalytic performances of the ZnO/Ti3C2 photocatalysts were evaluated by the degradation of methyl orange (MO) under UV–visible light irradiation. The photocatalytic activity of ZnO was obviously enhanced with a trace amount of Ti3C2. The pseudo-first-order rate constants of the ZnO/Ti3C2-0.05 and ZnO/Ti3C2-0.5 with Ti3C2 mass percentages of 0.041% and 0.41%, respectively, were 2.9 and 4.2 times higher than that of the ZnO. The enhanced photocatalytic activity of ZnO/Ti3C2 composite was due to the increased transfer of photo-generated charge carriers. Furthermore, the ZnO/Ti3C2-0.5 composite also showed good stability, the degradation efficiency of MO was still maintained 99% even after 10-cycle of reutilization. ZnO/Ti3C2 and other Ti3C2-containing composites may have potiential application in wastewater treatment and environment remediation.

Direct fabrication of metal-free graphene nanohairs/polyimide heterojunction for the highly efficient photocatalytic degradation of industrial dyes

A single-step three-dimensional graphene nanohairs/polyimide heterojunction (GPH) is fabricated using a CO2 laser-assisted method. An optimization process has been systematically carried out to obtain high-quality graphene nanohairs on polyimide. The obtained GPH was characterized by X-Ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. Using the fabricated GPH as a photocatalyst, the photocatalytic degradation of three industrial dyes namely, methyl orange (MO), methylene blue (MB), and Rhodamine B (RhB), was studied under UV irradiation. The decolorization of the samples was studied by UV–vis absorbance spectrometer. Starting from 5 ppm dye solutions with GPH, the degradation efficiencies of 97 % for MO in 60 min, 98 % for RhB in 90 min, and 88 % for MB in 170 min, were achieved. Furthermore, the stability of GPH was evaluated and after five runs, the degradation efficiency of MO, RhB and MB is decreased to 85 %, 91 % and 75 % from 98 %, 97 %, and 88 %, respectively. The mechanism for the degradation of dyes using GPH was proposed. The simple and feasible fabrication of GPH with excellent photocatalytic dye degradation efficiency would create the new insight into the flexible heterostructures for degrading the industrial wastewater treatment process.

Tungsten Oxide Morphology-Dependent Au/TiO2/WO3 Heterostructures with Applications in Heterogenous Photocatalysis and Surface-Enhanced Raman Spectroscopy

Developing highly efficient Au/TiO2/WO3 heterostructures with applications in heterogeneous photocatalysis (photocatalytic degradation) and surface-enhanced Raman spectroscopy (dye detection) is currently of paramount significance. Au/TiO2/WO3 heterostructures were obtained via heat or time-assisted synthesis routes developed by slightly modifying the Turkevich–Frens synthesis methods and were investigated by TEM, SEM, XRD, Raman spectroscopy, XPS, photoluminescence, and UV–vis DRS techniques. Structural features, such as WO3 crystalline phases, TiO2 surface defects, as well as the WO3 (220) to TiO2-A (101) ratio, were the key parameters needed to obtain heterostructures with enhanced photocatalytic activity for removing oxalic acid, phenol, methyl orange, and aspirin. Photodegradation efficiencies of 95.9 and 96.9% for oxalic acid; above 96% (except one composite) for phenol; 90.1 and 97.9% for methyl orange; and 81.6 and 82.1% for aspirin were obtained. By employing the SERS technique, the detection limit of crystal violet dye, depending on the heterostructure, was found to be between 10−7–10−8 M. The most promising composite was Au/TiO2/WO3-HW-TA it yielded conversion rates of 82.1, 95.9 and 96.8% for aspirin, oxalic acid, and phenol, respectively, and its detection limit for crystal violet was 10−8 M. Au/TiO2/WO3-NWH-HA achieved 90.1, 96.6 and 99.0% degradation efficiency for methyl orange, oxalic acid, and phenol, respectively, whereas its limit of detection was 10−7 M. The Au/TiO2/WO3 heterojunctions exhibited excellent stability as SERS substrates, yielding strong-intensity Raman signals of the pollutant molecules even after a long period of time.

Performance evaluation of Fe3O4@ACF-supported bio-electro Fenton system for simultaneous sewage treatment and methyl orange degradation

The development of an integrated wastewater treatment system is a challenging endeavor in modernized cities. Herein, a four-electrode-based electro Fenton coupled bio-electrochemical system (EF-BES) was developed to take advantages of both bio-electrochemical system (BES) and electro Fenton (EF) process in wastewater treatment. For it, a polarizable Fe3O4@ACF cathode was synthesized by the wet-phase activation to enhance the degradation power of the electrochemical advanced oxidation process, i.e., EF system. The iron particles in Fe3O4@ACF were used as a bridge for electron transfer to polarize the cathode. After 25-days, polarization of activated sludge inoculated BES generated an approximate of 275.23 ± 9.35 mW cm−2 of power density. The power was utilized as an energy source with which the EF-BES could degrade Methyl orange (MO) containing wastewater. At the optimum operating condition, the MO degradation efficiency 82.5 ± 4.27% could be achieved over 40 h. In addition to MO degradation, organics and NH4+ in sewage could be removed simultaneously; the observed TOC, COD and NH4+-N removal efficiencies were 67.4 ± 3.6%, 71.2 ± 3.8% and 69.3 ± 3.7%, respectively. Overall, the coupled EF-BES system is a promising treatment technology for MO-containing wastewater.

Improved Adsorption and Photocatalytic Degradation of Methyl Orange by Onion-like Nanocarbon/TiO2 Nanocomposites

Waste cooking oil, a known environmental pollutant, has been used as a precursor for the synthesis of onion-like nanocarbons (OLNCs) using flame pyrolysis. The OLNCs were added to TiO2 to form TiO2/OLNC nanocomposites through hydrothermal treatment. The TiO2/OLNCs ratio was varied by increasing the mass of the OLNCs (10, 20, 30, and 50 mg), while the mass of TiO2 (100 mg) was kept constant at C to TiO2 molar ratios of 1:2, 1:4, 1:6, and 1:10, respectively. The surface area of the photocatalysts increased with an increase in the mass of OLNCs. The nanocomposites were applied in the photocatalytic degradation of methyl orange. The photocatalysts showed a degradation efficiency trend of TC-10 > (99.9%) TC-20 > (90%) TC-30 > (81%) TC-50 > (70%) TiO2 (44%) in 120 min. A similar trend was observed from the first-order kinetic rate data. The degradation efficiency of methyl orange was improved by adding 5% H2O2 (99.9%) in 30 min. The OLNCs were responsible for increased photocatalytic activity due to a high adsorption efficiency compared to pure TiO2. The OLNCs acted as an electron acceptor, while the TiO2 acted as an electron donor. The enhanced catalytic behavior was achieved by hindering the recombination of e−/h+ in the composite and increasing the adsorption capability of TiO2.

A facile and green synthesis of Mn and P functionalized graphitic carbon nitride nanosheets for spintronics devices and enhanced photocatalytic performance under visible-light

Manganese and phosphorus co-doped, graphitic carbon nitride (g-C3N4) nanosheet (Mn/P-g-C3N4) is prepared by facile and green calcination process of melamine (C3H6N6), manganese chloride tetrahydrate (MnCl2·4H2O), and ammonium dihydrogen phosphate ((NH4)H2PO4). The Mn/P co-doping significantly enhances magnetic values compared to pristine-g-C3N4, phosphorus-doped g-C3N4 (P-g-C3N4), and manganese-doped g-C3N4 (Mn-g-C3N4). We find that Mn/P-g-C3N4 is a half-metallic ferromagnetic material having a magnetic moment and Curie temperature of 4.51 μB and ∼ 800 K, respectively. The ultraviolet–visible (UV–vis) absorption spectrum of Mn/P-g-C3N4 reveals superior absorption in broader wavelength compared to pristine-g-C3N4, P-g-C3N4, and Mn-g-C3N4. The methyl orange degradation efficiency of Mn/P-g-C3N4 photocatalyst is 94 %, which is three times more than that of pristine-g-C3N4 (29 %) and more significant than the P-g-C3N4 (46 %) and Mn-g-C3N4 (58 %). Furthermore, density functional theory (DFT) calculation explains the origin of high magnetic behavior, the boosted photocatalytic efficiency of Mn/P-g-C3N4, and the essential material properties like structure, bandgap, the density of states (DOS), and atomic level interaction. This work may be helpful for reasonably designing ferromagnetic material for spintronics devices and boosting visible-light (VL) photocatalytic performance for environmental remediation.

G-C3N4/TiO2/ZnIn2S4 graphene aerogel photocatalysts with double S-scheme heterostructure for improving photocatalytic multifunctional performances

The construction of aerogel photocatalyst materials with heterostructure is a practical and effective strategy to remove heavy metal ions, degrade pollutants, and conduct hydrogen evolution reactions. Herein, the isoelectric point assisted calcination technique is used to prepare a g-C3N4/TiO2/ZnIn2S4 graphene aerogel (CTZA) photocatalyst with a double S-scheme heterostructure using graphene aerogel as carriers, which can improve photocatalytic multifunctional performances. Under simulated sunlight illumination, through the joint action of photocatalysis and adsorption, the reduction rate of Cr(VI) by CTZA composites reaches 98.3% within 70 min, and the degradation efficiency of methyl orange (MO) reaches 97.5% within 30 min, which are much higher than the photocatalytic performances of the single samples. The charge transfer mechanism of the double S-scheme heterostructure in the CTZA photocatalytic system is proposed and confirmed via the combination of the DFT theoretical calculations with a series of experiments. In addition, the CTZA photocatalyst also displays a high hydrogen evolution rate (6531.9 μmol g−1). The excellent photocatalytic performance of CTZA is mainly due to the advantages of both the heterojunction photocatalyst and the graphene aerogel framework. The formation of a double S-scheme heterostructure can more effectively reduce the recombination of photo-induced carriers and increase the reduction and oxidation abilities. The graphene aerogel skeleton provides more active sites, and the unique three-dimensional network provides abundant electron transport channels, which extend the lifetime of light and accelerate the transport rates of carriers. This study shows that the aerogel photocatalyst has potential applications in solving energy and environmental problems.

Ultrafine sulfur–doped carbon nanoparticles enhanced the transmembrane bioelectricity of Clostridium butyricum for biohydrogen production

Inorganic–biohybrid systems refer to the combination of inorganic nanoparticles with intact living cells, which have shown great potential in microbial fermentative hydrogen production. However, the typical whole–cell biohybrid systems often suffer from sluggish electron transfer and additional energy loss during transmembrane diffusion, which severely restrict the efficiency of hydrogen production. Herein, sulfur–doped carbon nanoparticles (SCNPs) are prepared by top–down laser–assisted synthesis. The inorganic–biohybrid system is constructed by assembling the SCNPs with the Clostridium butyricum cells. As expected, the biohybrid system has good viability and stability, and the H2 production of this biohybrid system is 12.5 times higher than that of the bare bacteria. Furthermore, the degradation efficiency of methyl orange by Clostridium butyricum is verified, while this hybrid system could reach over 90% in 12 h. In addition, the mechanism of enhancing hydrogen evolution is investigated. SCNPs engulfed by Clostridium butyricum have rich surface charges, which improve the efficiency of electron transduction in bacterial cells, accelerate the generation of pyruvate in bacteria, and enhance the activity of hydrogenase, thereby realizing H+ reduction and H2 generation. This method provides a simple and effective way to improve the electron transfer efficiency and reduce the energy loss in the transmembrane diffusion process to build a powerful whole–cell biohybrid system for hydrogen production.