Visible-light Photocatalyst Research Articles

Smart chitosan Schiff base ferrite: a dual-action visible light photocatalyst for dye degradation and antimicrobial defense

This study presents the synthesis and applications of visible-light photocatalyst for environmental remediation.

Si@SbN: a promising solar photocatalyst for the reduction of NO.

Si@SbN, a highly promising visible-light photocatalyst for the NO reduction reaction (NORR), was studied by performing first-principles calculations. A novel design concept of the Si electron configuration applied to metal-free active sites has been explored. This Si-altered SbN enhances chemical NORR activity without taking into account complicated reaction mechanisms, facilitating the development of catalysts.

Ferrocenylselenoether and its cuprous cluster modified TiO2 as visible-light photocatalyst for the synergistic transformation of N-cyclic organics and Cr(vi).

In this study, fcSe@TiO2 and [Cu2I2(fcSe)2]n@TiO2 nanosystems based on ferrocenylselenoether and its cuprous cluster were developed and characterized by X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), and electron paramagnetic resonance (EPR). Under optimized conditions, 0.2 g L-1 catalyst, 20 mM H2O2, and initial pH 7, good synergistic visible light photocatalytic tetracycline degradation and Cr(vi) reduction were achieved, with 92.1% of tetracycline and 64.5% of Cr(vi) removal efficiency within 30 minutes. Mechanistic studies revealed that the reactive species ˙OH, ˙O2-, and h+ were produced in both systems through the mutual promotion of Fenton reactions and photogenerated charge separation. The [Cu2I2(fcSe)2]n@TiO2 system additionally produced 1O2 from Cu+ and ˙O2-. The advantages of the developed nanosystems include an acidic surface microenvironment provided by Se⋯H+, resourceful product formation, tolerance of complex environments, and excellent adaptability in refractory N-cyclic organics.

Construction of novel dual Z-scheme heterojunction of ternary CdS/g-C3N4/NiFe2O4 magnetically retrievable nanocomposite for boosted photocatalytic and energy storage applications

A novel CdS/g-C3N4/NiFe2O4 (CGN) ternary nanocomposite photocatalyst was rationally developed via a simple wet-impregnation technique. Looking at the band structure of the components of the catalyst, a novel dual Z-scheme heterojunction can be successfully developed, generating more active sites that rapidly encourage the separation of the photo-generated species, contributes to preventing the aggregation of the synthesized nanocomposite, and enhance the light absorption efficiency. Remazol Brilliant Blue R (RBBR) was photocatalytically degraded by the nanocomposite in the presence of visible light to assess its photocatalytic effectiveness. The CGN 2 ternary nanocomposite had the maximum photocatalytic activity (96 %) if compared to the other prepared photocatalysts, as the rate of degradation of pure CdS, CdS/g-C3N4, CGN 1, and CGN 3 nanocomposites were only around 53.4, 85, 87.5, and 92 %, respectively, keeping the irradiation time. Based on trapping tests, •OH, •O2− and h+ radicals are the main active species that play a vital role in the photocatalytic oxidation process. Even after the fourth cycle, the CGN 2 composite remained efficient in the successive photocatalytic degradation of RBBR , maintaining over 91 % of its first degradation efficiency. The CdS/g-C3N4/NiFe2O4 nanocomposite revealed outstanding cycling stability due to its inherent magnetic property, making it a promising choice as a visible light photocatalyst. The electrochemical energy-storage behavior of CGN 2 as active electrode material exhibited a remarkable specific capacitance of 195 F g−1 (67 C g−1) at 1 A g−1. It delivered an outstanding cycling stability of 91 % capacity retention after 2000 charge–discharge cycles. The obtained remarkable results indicate that the CGN 2 nanocomposite is a promising active electrode material for high-performance energy-storage supercapacitors.

Optimization of tetracycline antibiotic photocatalytic degradation from wastewater using a novel type-II α-Fe2O3-CeO2-SiO2 heterojunction photocatalyst: Performance, pathways, mechanism insights, reaction kinetics and toxicity assessment

The photocatalytic degradation of organic pollutants, especially tetracycline (TC), poses challenges in precisely targeting and selectively breaking down specific hazardous chemical groups. Herein, a new α-Fe2O3-CeO2-SiO2 (FeCeS) photocatalyst was synthesized and characterized by XRD, XPS, SEM, EDS, BET, PL, and TEM analyses. It was employed to optimize operational parameters, including photocatalyst dosage, TC concentration, pH levels, and visible irradiation time, in the photodegradation process of TC via the RSM-CCD method. The results indicate that the FeCeS heterojunction had a significant degradation efficiency (95.90 %) under optimum conditions (TC concentration: 25.1 mg/L, photocatalyst dose: 0.62 g/L, visible time: 94.2 min, and pH: 4.89) with the rate of 0.05 min−1. Additionally, a mineralization rate of >62 % was recorded for TOC, suggesting that the conversion of TC into environmentally safe compounds was successful. The degradation pathways of TC and its chemical intermediates were elucidated using HPLC/MS analysis. The results revealed the existence of two potential degradation routes. These findings offer valuable insights into the intricate mechanisms inherent in the photocatalytic process. The type-II FeCeS photocatalyst exhibits effective generation and separation of crucial reactive species, such as OH, O2−, and h+, which play essential roles in the degradation of TC. The synthesized photocatalyst significantly decreased the TC solution's toxicity and improved its biodegradability, according to the toxicity evaluation. This study presents a straightforward synthesis approach and impressive mineralization capability. Additionally, the recyclability of FeCeS enhances its potential as a viable option for widespread utilization as a visible light photocatalyst in removing antibiotics from natural water sources and controlling environmental contamination.

Catechol-formaldehyde resin microspheres@UiO-66-NH2@ CdS core-shell nanohybrids as robust visible-light photocatalyst for multifunctional applications

Well-defined zirconium based metal-organic frameworks (MOFs) coated polymer core-shell nanohybrid (CFR@MOF) was constructed using catechol formaldehyde resin (CFR) microspheres as a support, followed by encapsulating CdS nanoparticles (NPs) into MOF (UiO-66-NH2) shell layers to obtain CFR@UiO-66-NH2@CdS nanohybrids to enhance visible photosensitization for multifunctional photocatalytic applications including organic pollutant degradation, water disinfection and photoinduced atomic transfer radical polymerization (photoATRP). The CFR microspheres with a regular spherical morphology (200–400 nm) provided a versatile initial platform for the growth of MOF shells through mononuclear coating. The impact of different loadings of CdS NPs incorporated into CFR@UiO-66-NH2 shells on photocatalytic performance was systematically investigated. CFR@UiO-66-NH2 @CdS demonstrated robust dye degradation and antibacterial ability. Especially, a remarkable inhibitory efficiency of 99.99 % and 99.7 % was achieved for S. aureus and E. coli, with a low photocatalyst dosage (100 μg/mL) under visible light. Furthermore, by combining CFR@UiO-66-NH2@CdS with CuBr2/L catalysts, a high-efficiency red-light triggered photoredox catalytic polymerization system was established in photoinduced atom transfer radical polymerization (photoATRP), achieving high conversion rate (>90 %) for various monomers in a short time.

In situ reversible assembly of atomic interfacial structure in BiOI/Bi5O7I p-n heterojunctions to promote visible-light photocatalysis

Constructing efficient p-n heterojunctions holds great potential in the realm of photocatalysis for promoting the sustainable development of the environment and energy industries. However, traditional p-n heterojunctions suffer from limited interfacial interaction which severely restricts the effectiveness of the built-in electric field in boosting charge separation. Herein, we present an in situ reversible assembly approach to fabricate functional p-n junction in BiOI/Bi5O7I composites at room temperature. By controlling the reaction time or the amount of KI precursor added, we attain the as-designed BiOI@Bi5O7I and Bi5O7I@BiOI heterojunctions with large specific surface area and ample interfacial electric field. Subsequent application of the optimized heterojunction material as visible-light photocatalyst achieves efficient photoreduction of CO2 reactant into CO product (0.46 μmol g−1h−1), even without using any sacrificial agent in the gas–solid reaction system. This catalytic performance is notably ∼ 6.6 times and 15.3 times higher than that of standalone BiOI and Bi5O7I materials, respectively. In situ XPS, in situ Kelvin probe force microscopy, and theoretical calculations reveal that the built-in electric field induces directional charge transfer to greatly boosts the efficiency of separating photogenerated electron-hole pairs at the interface of BiOI and Bi5O7I. This study provides valuable insights for the rational design and straightforward fabrication of next-generation, integrated heterostructured photoelectronic materials for efficient energy, environmental, and chemical applications.

Machine learning aided design of Bi2WO6/MIL-53(Al) nanocomposites

It is a very rewarding work to quickly develop a new type of visible-light photocatalyst Bi2WO6/MIL-53(Al) (BWO/MIL) nanocomposites with desired property in enormous material synthesis space. In the work, the BWO/MIL predictor based on machine learning method was established by using the synthetic parameters to accelerate the design of BWO/MIL nanocomposites. The forward feature selection, genetic algorithm based on support vector regression (SVR), and genetic algorithm based on gradient boosting regression (GBR) were employed to screen the key features from candidate features related to synthetic parameters of BWO/MIL nanocomposites. The correlation coefficients (R) of the SVR model with radial basis function (RBF) were 0.904 and 0.929 for ten-fold cross validation and the external test, respectively. The two R values of the GBR model were slightly lower than the SVR model. The potential BWO/MIL nanocomposites with desired property were discovered by the SVR-RBF model and virtual screening from the huge synthesis space of BWO/MIL nanocomposites. An online web service (http://1.14.49.110/online_predict/BWO1) was developed to quickly predict photocatalysis activity of BWO/MIL nanocomposites. The methods mentioned here can accelerate the design of BWO/MIL nanocomposites and cut the cost of BWO/MIL synthesis.

Enhanced removal of perfluoroalkyl substances using MMO-TiO2 visible light photocatalyst

Exploration of easily produced visible light photocatalysts is still necessary. Thus, this study investigated the catalytic performance of a mixed metal oxide-titanium dioxide (MMO-TiO2) to remove perfluorooctanoic acid (PFOA), a typical and harmful perfluoroalkyl substance, under visible light conditions. Analysis of degradation efficiencies revealed that MMO-TiO2 exhibited a remarkable removal efficiency of 95.99 ± 1.49 %, surpassing other catalysts, including TiO2, ZnAl, MMO, and ZnAl-TiO2. MMO-TiO2, derived from ZnAl-TiO2 calcination, displayed a 5.66-fold higher apparent degradation rate constant (1.07 × 10−2 min−1) compared to ZnAl-TiO2 (1.89 × 10−3 min−1). These materials were characterized via X-ray powder diffractometry, Fourier transform infrared-attenuated total reflectance, N2 adsorption-desorption analysis, and field emission-scanning electron microscopy. Results revealed that O2•- radicals play a pivotal role as the predominant species that mediate PFOA removal. Comparative experiments using probe compounds confirmed increased O2•- production during MMO-TiO2 photoreaction under visible light. In addition, this study explored the effect of operational parameters, such as catalyst dose, initial PFOA concentration, solution pH, and water matrices on the photocatalytic removal process. These findings provide insight into the removal of PFOA using MMO-TiO2, highlighting the potential of this visible light catalyst for the eco-friendly removal of persistent organic pollutants in aquatic systems.

Pd@Bi2Ru2O7/BiVO4 Z-Scheme Heterojunction Nanocomposite Photocatalyst for the Degradation of Trichloroethylene.

Photocatalytic degradation of chlorinated persistent organic pollutants is a very challenging process due to the high redox potential of the C-Cl bond that requires wide band gap catalysts that are activated under UV light. Designing a Z-scheme heterojunction between visible light-activated metal oxides with compatible band gaps enables these redox potentials. Herein, we report the design of a pyrochlore/Aurivillius Z-scheme heterojunction to enhance the photocatalytic activity of BiVO4 for the degradation of trichloroethylene. We prepared Bi2Ru2O7/BiVO4 heterostructured photocatalysts by a controlled hydrothermal approach. Upon optimizing the Bi2Ru2O7 ratio to 1.0 wt %, the heterostructured photocatalyst demonstrated enhanced activity in the degradation of trichloroethylene (TCE) under simulated sunlight irradiation compared to bare BiVO4 and Bi2Ru2O7, respectively. Decorating the surface of the catalyst with palladium nanodomains to create the Pd@Bi2Ru2O7/BiVO4 nanocomposite showed a substantial increase in the photocatalytic degradation of TCE. The material characterization indicated that the architecture of the material provides a synergy of enhancing the redox potential of the photocatalyst and improving the charge carrier dynamics. Furthermore, the photoelectrochemical characterization confirmed that the dual heterojunctions in the Pd@Bi2Ru2O7/BiVO4 nanocomposite resulted in improved interfacial charge carrier transfer and enhanced the electron/hole separation efficiency compared to the nonpalladized catalysts. This work provides a promising approach for band gap engineering of visible light photocatalysts for the degradation of halogenated persistent organic pollutants.

Decoration of 0D Bi3NbO7 nanoparticles onto 2D BiOIO3 nanosheets as visible-light responsive S-scheme photocatalyst for photo-oxidation of antibiotics in wastewater

In this work, a new S-type hybrid composed of 2D BiOIO3 and 0D Bi3NbO7 was proposed and hybridized by a facile self-assembly strategy. The developed nanomaterials were characterized and identified by a series of sophisticated analyses, like XRD, SEM, EIS, XPS, PL, UPS, EDS, BET, M-S, TEM, HRTEM, and DRS. The photocatalytic behavior of BiOIO3/Bi3NbO7 was examined and optimized against amoxicillin (AMX) and other types of antibiotics under a variety of environmental conditions, such as visible light (150 W LED), direct sunlight, pH (3–11), catalyst dosages (20–80 mg), humic acid (0–24 mg/L), AMX concentration (10–40 mg/L), and different inorganic ions (0.05 M). The optimized BiOIO3/Bi3NbO7 hybrid attained exceptional AMX degradation activity (96.5%) under visible light (60 min), with a reaction constant of up to 0.04559 min−1, exceeding bare BiOIO3 and Bi3NbO7 by 5.57 and 5.3 folds, respectively. The obtained BiOIO3/Bi3NbO7 hybrid unclosed expanded light utilization behavior compared with neat catalysts, which originates from the powerful incorporation between BiOIO3 and Bi3NbO7 in the S-type system. The radical investigations confirmed the superiority of BiOIO3/Bi3NbO7 in generating both •OH and •O2− during the photoreaction. The novel Bi3NbO7-based heterojunction afforded robust photostability in five treatment cycles and simple charge transfer activity in the S-type route, boosting the photo-mechanism for antibiotic degradation in an efficient manner. The building of the S-scheme heterojunction between BiOIO3 and Bi3NbO7 stimulates the utilization of holes by the recombination process and promotes the overall stability of the composite. Our study introduces a new class of semiconductor heterojunctions that may contribute to the development potential of the photocatalysis sector in wastewater treatment.

Interface charge separation in Cu2CoSnS4/ZnIn2S4 heterojunction for boosting photocatalytic hydrogen production

The practical application of hexagonal ZnIn2S4 (ZIS) as a visible-light photocatalyst for hydrogen (H2) production is hindered by rapid internal charge recombination. In this study, we successfully synthesized Cu2CoSnS4 (CCTS) nanocrystals and loaded them onto the surface of ZIS nanosheets to create a p-n heterojunction photocatalyst. The optimized Cu2CoSnS4/ZnIn2S4 (CCTS/ZIS) heterojunction exhibited a significantly higher visible-light photocatalytic H2 evolution rate of 4.90 mmol·g−1·h−1 compared to ZIS and CCTS alone. The enhanced photocatalytic efficiency was attributed to improved electron transfer and charge separation at the heterojunction interface. The formation of p-n heterojunction facilitated the accumulation of valence band electrons in ZIS and conduction band holes in CCTS, effectively suppressing the recombination of photogenerated electrons and holes. Theoretical calculations, spectroscopic, and photoelectrochemical characterizations supported the findings. This work presents a promising approach for designing efficient p-n heterojunction semiconductor photocatalysts for practical applications in visible-light-driven hydrogen evolution.

High carrier mobility ZrSSe/SnX (X=S, Se, S2, Se2) vdW heterostructures for photocatalytic overall water splitting: A first-principles study

Recently, the assembly of novel two-dimensional materials via van der Waals (vdW) interactions to form heterostructures is considered an effective strategy for producing materials with enhanced photocatalytic activities. This study systematically explored the optoelectronic and photocatalytic properties and carrier mobilities of novel ZrSSe/SnX (X = S, Se, S2, Se2) vdW heterostructures using density functional theory. The formation energies, elastic constants, phonon dispersions, and results of ab-initio molecular dynamic simulations indicate structural, mechanical, dynamic, and thermal stability. The electronic band structure and optical properties are calculated using hybrid functional HSE06 for accurate calculations. The results of calculations using the bandgap center technique based on density functional theory show that ZrSSe/SnSe, ZrSSe/SnS2, and ZrSSe/SnSe2 heterostructures possess suitable band edges for photocatalytic overall water splitting. The optical absorption spectrum covers a broad range from 104 in the visible region and increases to 105 in the UV region. Furthermore, the ZrSSe/SnX (X = S, Se, S2, Se2) heterostructures have high carrier mobilities of the order of 105. High mobilities help carriers to move quickly and reduce the recombination rate of holes and electrons. The findings indicate that ZrSSe/SnX (X = S, Se, S2, Se2) heterostructures are potentially efficient visible-light photocatalysts for overall water splitting.

KCl mediated Ag/Co@Fe2O3/C3N4 heterojunction as a highly efficient visible photocatalyst for tetracycline degradation: Application of machine learning

In this work a new KCl mediated Ag/Co@Fe2O3/C3N4 heterojunction was synthesized by a simple coprecipitation method and was characterized. The band gap of the synthesized heterojunction was calculated as 2.1ev indicating its good potential for using as visible light photocatalyst. The synthesized heterostructure was used for photodegradation of tetracycline and the experimental conditions were optimized. The results showed with 0.04g of heterostructure catalyst, the degradation of tetracycline 50ppm can be perform in a short time (40 min ) with efficiency 100%. The enhanced photoactivity of this catalyst is due to unique structure of KCl mediated Ag/Co@Fe2O3/C3N4 heterojunction that can decrease the charge recombination and therefore, leading highly efficient visible light photocatalyst. Experimental data also were analyzed using various regression models based on machine learning techniques, particularly neural networks. The outcomes reveal the effectiveness of neural network models as they demonstrate negligible Mean Root Squared Error (MRSE) values and nearly perfect R-squared scores. This highlights the excellence and accuracy of the neural network models in capturing and predicting the patterns and trends within the experimental data.

Yellow TiO2 from titanium peroxo complexes: Verification of the visible light activity and a rational enhancement of its photocatalytic efficiency

It is widely believed that colored TiO2 materials (yellow, blue, black, violet, etc.) are visible-light active photocatalysts. In this article, we verify this claim with respect to the yellow TiO2 photocatalyst that has been synthesized using peroxo-titanium complexes formation route. The surface oxygen species, the electronic structure, the photoelectrochemical properties, and the photoactivity of yellow TiO2 have been investigated. FT-IR and XPS analysis confirms the presence of surface peroxo-species that caused the yellow color. Spectroelectrochemical measurements confirmed the absorption of violet light (400–430 nm). The reduced band gap energy (3.05 eV) has resulted from the anodic shift of both conduction and valence band edges by 0.30 and 0.15 eV, respectively. However, the wavelength-dependent photocurrent generation by yellow TiO2 in the presence of oxygen and under deaerated conditions proved that it does not contribute to the photoactivity enhancement in the visible region (λ > 400 nm). The proposed mechanism has shown that although the driving force at the oxidation side is theoretically improved, the reduction counterpart is parallelly weakened and the photoinduced electrons cannot efficiently reduce regular electron acceptors in aqueous systems (e.g., O2, H2O). Adding a low amount of a stronger electron acceptor (e.g., H2O2) into the system provides extra HO• radicals through the reductive mechanism. At higher concentrations of H2O2, the oxidation of H2O2 is more favorable. The hydroxylation of terephthalic acid via the oxidative and reductive pathway along with the bleaching of Congo Red indicates improved photocatalytic activity due to enhanced hydrogen peroxide activation. Although yellow TiO2 is active only upon UV light irradiation, this paper reports how to boost the photocatalytic activity of this material.

Fabrication of WO3 photocatalyst by plasma assisted ball milling under different discharge atmospheres

A convenient method for producing single oxide WO3-x at room temperature through plasma milling was reported, resulting in a highly efficient visible-light photocatalyst. By altering the discharge atmosphere during plasma milling from ammonia and nitrogen to argon, the color of the milled monoclinic WO3 powders deepens from blue to dark blue, indicating an increased concentration of oxygen vacancies. The morphological and structural properties of the monoclinic WO3 powders, prepared using different ball milling techniques, are characterized using XRD, SEM, TEM, Raman, XPS, EPR, and UV–vis. These results reveal that plasma milling leads to a higher surface area, increased presence of oxygen vacancies, and more defects compared with conventional milling, resulting in a greater number of more reactive sites and a larger contact area between monoclinic WO3 nanoparticles and RhB solution. Consequently, monoclinic WO3 samples fabricated through Ar-P-milling exhibit the highest photocatalytic activity. This is attributed to the reduction of the WO3−x band gap to 2.28 eV by Ar-P-milling with high oxygen vacancies. This lower bandgap markedly improves the light utilization rate, thereby enhancing the overall photocatalytic efficiency. The Ar-P-milled WO3 shows the highest degradation rate constant of 0.037 min−1, which is 4 times higher than that of pure monoclinic WO3.

Step-by-step tuning of morphology and band gap of ZnS/MoS2 photocatalyst for enhanced visible light to hydrogen fuel conversion

To address the inherent limitations of ZnS and MoS2 as visible light photocatalysts, herein, we report a step-by-step tuning of mixed sulfide composite system (ZnS/MoS2) to achieve enhanced visible light to hydrogen fuel conversion efficiency in the absence of any sacrificial agents. In the first stage, ZnS/MoS2 composite was synthesized by using a single step hydrothermal route and the photocatalytic activity of the synthesized ZnS/MoS2 composite was tuned by varying the ratio of Zn and Mo in the composite. In the second stage, the photocatalytic efficiency of the composite was further enhanced by tuning the band gap and visible light absorption characteristics of the material through cobalt doping (Co-doping) in the MoS2 co-catalyst. The hydrogen generation activity of the tuned composition (1:1.3 ratio of Zn and Mo) of the ZnS/MoS2 composite with 3% Co-doping is obtained as the best (1256 μmol of H2 in 1 h) as compared to the other compositions of the doped composites (1%, 3% and 5% Co doping). The enhanced hydrogen generation through visible light induced water splitting of the developed mixed sulfide composite systems (ZnS/MoS2 and ZnS/Co-doped MoS2) even in the absence of any sacrificial agents is ascribed to their tuned band gap and low electron-hole recombination rate.

Facile preparation of high-performance hydrochar/TiO2 heterojunction visible light photocatalyst for treating Cr(VI)-polluted water

In order to remedy the shortcomings of narrow absorption wavelength range and low photogenerated carrier separation efficiency of TiO2 photocatalyst, hydrochar (HC) was chosen to modify TiO2 by constructing HC/TiO2 heterojunction composite. HC/TiO2 composites were synthesized from glucose, tetrabutyl titanate and deionized water by a simple one-pot hydrothermal way, and their photocatalytic Cr(VI) reduction properties were studied. The results indicated that HC/TiO2 composites had tremendously improved photocatalytic Cr(VI) reduction activity, in comparison with TiO2, HC and a number of newly reported TiO2-based visible light photocatalysts. When the mass percentage of glucose to tetrabutyl titanate was 14, the obtained HC/TiO2-2 possessed the maximal photocatalytic activity, which was 19 times that of TiO2 and 14.3 times that of HC under visible light (wavelength > 420 nm) irradiation, and 3.2 times that of TiO2 under ultraviolet-visible light (Xenon lamp) irradiation. Furthermore, the photocatalytic stability of HC/TiO2-2 was also excellent. Additionally, proper choice of the photocatalysis experiment parameters could further raise the photocatalytic Cr(VI) reduction efficiency of HC/TiO2-2. The exceptionally elevated photocatalytic activity of HC/TiO2-2 was found to be due to its type-II heterojunction structure, which drastically heightened the separation and transfer efficiencies of photogenerated electrons and holes. Besides, HC/TiO2-2 also showed great potential for practical application in photocatalytic treatment of the Cr(VI) effluents discharged from freezing brine and black chromium plating industries.

Ni/Mn metal–organic framework decorated bacterial cellulose (Ni/Mn-MOF@BC) and nickel foam (Ni/Mn-MOF@NF) as a visible-light photocatalyst and supercapacitive electrode

Recently, metal–organic frameworks (MOFs) and hybrids with biomaterial are broadly investigated for a variety of applications. In this work, a novel dual-phase MOF has been grown on bacterial cellulose (BC) as a biopolymer nano-fibrous film (Ni/Mn-MOF@BC), and nickel foam (Ni/Mn-MOF@NF) using a simple reflux method to explore their potential for photocatalyst and energy storage applications. The studies showed that the prepared Mn and Ni/Mn-MOFs display different structures. Besides, the growth of MOFs on BC substantially changed the morphology of the samples by reducing their micro sized scales to nanoparticles. The nanosized MOF particles grown on BC served as a visible-light photocatalytic material. Regarding the high surface area of BC and the synergistic effect of two metal ions, Ni/Mn-MOF@BC with a lower band gap demonstrates remarkable photocatalytic degradation efficiency (ca. 84% within 3 h) against methylene blue (MB) dye under visible light, and the catalyst retained 65% of its initial pollutant removal properties after four cycles of irradiation. Besides, MOF powders deposited on nickel foam have been utilized as highly capacitive electrochemical electrodes. There, Ni/Mn-MOF@NF electrode also possesses outstanding electrochemical properties, showing a specific capacitance of 2769 Fg−1 at 0.5 Ag−1, and capacity retention of 94% after 1000 cycles at 10 Ag−1.

Degradation of multiple xanthates using highly efficient visible light-responsive BiOBr-TiO2 composite photocatalysts

BiOBr-TiO2 (BT) composite photocatalysts were synthesized by using a two-step method including hydrothermal synthesis and water-bath precipitation. The microstructural characterization analysis proved that high-crystallinity and high-purity binary BT materials were achieved without by-products. TiO2 nanoparticles with a diameter of approximately 15 nm were decorated on multi-layered BiOBr nanosheets. The results showed that BT had highly-improved adsorption capacity and photocatalytic efficiency in comparison to pristine BiOBr and TiO2. The reaction rate constant of the optimal BT-2 composite photocatalysts for the degradation of 20 mg/L sodium ethyl-xanthate could reach 0.06496 min−1, which was 2.7 and 40.3 times than pure BiOBr and TiO2, respectively. The free radical scavenger test demonstrated that photogenerated holes were the main active species in the photocatalytic degradation reaction process. A possible degradation pathway for SEX molecules was provided through the interaction of visible light and BT-2 photocatalyst. The as-prepared BT materials can be used as efficient photocatalysts to completely degrade various types of xanthates under visible light.