Degradation Efficiency Of RhB Research Articles

Bi2MoO6/MgIn2S4 S-scheme heterojunction with rich oxygen vacancies for effective organic pollutants degradation: Degradation pathways, biological toxicity assessment, and mechanism research

Designing and constructing novel photocatalysts for organic pollutant degradation is of critical significance for water environment treatment. Constructing a Bi2MoO6/MgIn2S4 (BMO/MIS) S-scheme heterojunction with oxygen vacancies, which efficiently removed RhB within visible light irradiation. Oxygen vacancies regulated the band structure of Bi2MoO6 (BMO) and enhanced the adsorption of RhB on the catalyst's surface. The S-scheme heterojunctions contributed to the separation and transfer of photo-generated charge, retained the optimal redox ability of Bi2MoO6-Vo (BMO-Vo) and MgIn2S4 (MIS) at the same time. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) further confirmed the S-scheme charge transfer mechanism and the presence of oxygen vacancies. Within 30 min of visible light irradiation, RhB was completely degraded by BMO/MIS-8%, while the degradation efficiency of RhB by BMO-Vo and MIS were only 39.93 % and 80.87 %, respectively. The kinetics constant is 0.1035 min−1 of BMO/MIS-8%, which was 20.29 and 1.95 times that of BMO-Vo and MIS, respectively. At the same time, BMO/MIS-8% achieved removal efficiency of 24.28 %, 56.53 %, 59.15 % and 100 % for MO, TC,H-TC and MB, respectively. Compared to the previously synthesized Bi-ZFO/BMO-Vo photocatalyst, BMO/MIS-8% demonstrated superior degradation efficiency, exhibiting a degradation kinetic constant that was 2.12 times greater than that of Bi-ZFO/BMO-Vo under visible light irradiation. To improve the practical application of BMO/MIS, the effects of pH, co-existing ions and types of pollutants on degradation efficiency were evaluated. In addition, the biological toxicity assessment showed a significant decrease in the toxicity of RhB degradation products. This work provides a feasible avenue for constructing Bi2MoO6-based heterojunctions to treat dye wastewater.

Highly dispersed g-C3N4 on one-dimensional W18O49/carbon nanofibers for constructing well-connected S-scheme heterojunctions with synchronous H2 evolution and pollutant degradation performance

Synchronous dual-functional photocatalytic reaction can simultaneously consume photogenerated electrons and holes, leading to redox reaction, which is a promising photocatalytic reaction system model. However, the severe recombination of photogenerated charge carriers in photocatalysts limits their photocatalytic performance. In this work, W18O49/C@g-C3N4 S-scheme heterojunctions nanofibers with core-shell structure were prepared through electrospinning combined with the vapor deposition method, for high-performance synchronous photocatalytic H2 evolution and pollutant degradation. The X-ray photoelectron spectroscopy and Mott-Schottky results demonstrated that the S-scheme heterojunctions effectively separate charges while maintaining high redox capacity. The UV-vis-NIR absorption spectra results revealed the LSPR effect in W18O49, which can generate “hot electrons”. The scanning electron microscope images showed that the unique core-shell structure independently consumes electrons and holes, thereby enhancing charge separation and accelerating carrier kinetics. Specifically, the synchronous H2 evolution and RhB degradation efficiency of W18O49/C@g-C3N4 nanofibers were approximately 5.60 and 3.51 times higher than that of W18O49/C, and 2.45 and 22.55 times higher than that of C@g-C3N4 nanofibers, respectively. Furthermore, the ultra-long one-dimensional network structure of W18O49/C@g-C3N4 nanofibers enables easy recycling after liquid reactions. This study presents a novel approach for customizing band structures and unique surface morphology to improve synchronous dual-functional photocatalytic activity.

Designing a hollow MoSe2/CuS nanospheres type-II heterojunction photocatalyst with superior UV-vis-NIR absorption for photocatalytic degradation of organic pollutants.

In this work, a hollow MoSe2/CuS type-II heterojunction was fabricated using hollow MoSe2 nanospheres as the basis for structural design. UV-Vis-NIR diffuse absorption tests show that MoSe2/CuS has a broad spectral absorption to extend the optical response range from UV-Vis to NIR. The light source utilization rate and interfacial area are increased by the hollow MoSe2/CuS core-shell structure. The broad absorption ability of MoSe2/CuS can facilitate the photocatalysis process. As the electrochemical impedance of MoSe2/CuS is lower than that of the MoSe2, MoSe2/CuS has a good photogenerated carrier separation efficiency. Benefiting from the synergistic facilitation effect of the multi-level 3D hollow nanosphere and the significant space charge region in type-II heterojunction, the RhB degradation efficiency of MoSe2/CuS reached 96.0% in 120.0minunder Xe (350W) broadband spectrum light irradiation. The photocatalysis mechanism of the hollow MoSe2/CuS core-shell structure was investigated. This work provides an insight into the application of broad spectrum semiconductor heterojunctions to solve environmental problems.

A high-flux, photocatalytic wood-derived filter for high-efficiency water purification

Wastewater purification has evolved into a global problem in the face of increasing scarcity of freshwater resources. Photocatalysis technology possesses prominent advantages in treating pollutants in water because of its low cost and mild reaction conditions, which provides an effective way to treat multiple pollutants and reduce membrane fouling. Herein, we combine photocatalysis technology with filtration technology via in situ reduction Bi0 with Bi2SiO5 strategy incorporating a carbonized wood filter to synthesize carbon/Bi2SiO5@Bi bi-functional composite. Thus, simultaneous filtration and photocatalytic degradation of Rhodamine B and tetracycline were achieved. After filtrating for 30 min, the degradation rate of RhB and TC were 94.23 % and 81.39 %, respectively. Especially, the flux of RhB and TC were up to 2162.16 L m−2 h−1 and 1811.32 L m−2 h−1. In addition, the composite filter also has good recyclability and reusability, after 5 cycles, the degradation efficiency of RhB remains at 91 %. This study utilized photocatalytic technology combined with membrane filtration technology to successfully solve the contradiction between catalytic efficiency and water flux, which realized rapid and dynamic removal of organic pollutants from water. Besides, the use of carbonized wood-based materials provides a potential biomass technology for the preparation of bifunctional photocatalytic filters.

Boosting nitrogen photofixation through interface electron reconstruction using mixed-valent copper as mediator

Solar energy as the inexhaustible and pollution-free renewable energy is widely accepted. Photocatalysis is an efficient green process to store solar energy in the form of chemical energy or utilize it for NH3 production or water treatment reactions. Herein, CeO2–CeCO3OH all-solid-state heterojunctions with Cu2O/Cu Schottky barrier medium are assembled firstly, and the remarkable photo-catalytic performances are obtained. The heterojunction structure can promote the separation efficiencies of photo-induced electron-hole pairs. Otherwise, the as-prepared catalysts also have more visible light absorption capacities and photo-generated oxygen vacancies. In this photocatalytic system, the NH3 yield rate can reach above 597 or 992 μmol·gcal−1·h−1 under the vis-light or full-spectrum lighting without any sacrificial additives, and increase at least 3 times compared to the initial materials. The AQE at 420 nm also reaches more than 0.8 %. Furthermore, the RhB degradation efficiency for the modified sample is approximately 90 %, and the kinetic constant significantly exceeds that of initial sample by 2.7 times. It is the photo-introduced h+ and·O2− species working together to further improve the dye degradation process. This research provides a new insight for the fabrication strategy of photo-catalytic N2 fixation materials.

Co-doped C3N5 with enhanced RhB degradation by activating PMS

The application of advanced oxidation processes in wastewater treatment has attracted wide attention, in the past year. With excellent photoelectric properties and catalytic stability, graphitic carbon nitride and its derivatives have high catalytic performance. Compared to traditional g-C3N4 materials, g-C3N5 has a narrower band gap (g-C3N5 has a band gap of about 2.0 eV and g-C3N4 has a band gap of about 2.6 eV) and better electron excitation distribution due to it has a higher proportion of N atoms. In this study, the composites of Co atom doped g-C3N5 were synthesized and characterized. Co atoms are successfully doped into g-C3N5, which is proved by TEM, XPS and XRD experimental results. PMS can be activated by Co-C3N5, and RhB degradation efficiency is as high as 95.8 % within 40 min. The experimental results show that the doping of metal Co can effectively improve the catalytic performance of carbon nitride materials. The degradation efficiency of RHB activated by C3N5, C3N4 and Co-C3N4 was 18.2 %, 11.2 % and 41.8 %, respectively, while the degradation efficiency of Co-C3N5 was as high as 95.8 %. RhB was effectively degraded over a wide pH range (3.0–10.9) and under various anion conditions, indicating the excellent environmental suitability of Co-C3N5. The results of free radical quenching experiments and EPR tests showed that the contribution of active species to RhB degradation was as follows: SO4•− >1O2 > O2•−. This paper provides a new perspective using Co-C3N5 as a catalyst for PMS-based Fenton reaction.

Charge transfer dynamics in C3N4 encapsulated Cs3Bi2Br9 nanocrystals heterojunction for photocatalytic application

Perovskite materials have shown great application prospects in the field of photocatalysis due to their excellent photoelectric properties. However, the toxicity of lead and material instability limit its application. In this work, the heterojunction based on C3N4 thin layer encapsulated lead-free Cs3Bi2Br9 nanocrystals was constructed by electrostatic self-assembly method. This combination way does not disrupt the electronic, crystalline and structural properties of C3N4 and Cs3Bi2Br9. Fluorescence quenching in C3N4/Cs3Bi2Br9 composite is ascribed to the charge transfer process, which could be directly observed by spatially and temporally resolved fluorescence mapping image. The synergistic effect between C3N4 and Cs3Bi2Br9 can significantly improve the photocatalytic degradation efficiency of RhB, 98 % at 1 h. The stability of the composite was enhanced due to the special encapsulation effect. This work will provide a guideline for the construction of two-dimensional materials and perovskite heterojunction systems in the field of photocatalysis.

Preparation and Performance Study of S-Doped g-C3N4 Photocatalyst

In order to further improve the photocatalytic performance of pure CN, SCN (1:1), SCN (1:2), and SCN (2:1) photocatalysts were prepared using a one-step thermal polymerization method. The morphology of the prepared pure CN and SCN was characterized using SEM, XRD, UV, PL, and XPS to identify the reasons for their improved performance. Proved the photocatalytic degradation effect of prepared CN and SCN on RhB solution. The photocatalytic degradation efficiency of RhB by SCN (1:1) is 90.3%, which is nearly 1.72 times higher than that of CN52.38%. After a series of characterization, it was found that the SCN photocatalyst layer is thinner than the CN photocatalyst layer, and a large number of micron sized pores are distributed on the surface of SCN, increasing the specific surface area of SCN. Introducing an appropriate mass ratio of S element will improve the crystallinity of SCN photocatalysts. An appropriate mass ratio of SCN can reduce the band gap, which decreases from 2.70 eV corresponding to CN to 2.62 eV (1:1) of SCN. The photoresponse range undergoes a red shift, which is beneficial for the photocatalytic reaction and thus improves the performance of the photocatalyst. SCN can inhibit the recombination of photo generated electrons and holes, and improve the activity of photocatalysts.

Synthesis of g-C3N4/HC composite and its visible light catalytic performance

Thermal polymerization prepared g-C3N4/HC composite with good visible light catalytic ability using corn stover and urea as raw materials. The structure of the g-C3N4/HC composite was characterized by XRD, and it was determined that the composite was composed of g-C3N4 and HC. The morphology of the g-C3N4/HC composite was characterized by SEM. g-C3N4 is dispersed in sheet form on HC tubes with a regular porous structure. The degradation efficiency of RhB by g-C3N4/HC reached 99.14% after 70 min irradiation by a 70 W metal halide lamp. The cyclic degradation experiments proved that g-C3N4/HC has good reusability. Compared with g-C3N4, the visible light absorption capacity of g-C3N4/HC is enhanced, and the electron-hole recombination rate is also reduced, which results in the higher photocatalytic capacity of g-C3N4/HC. The free radical trapping experiments confirmed that the hole free radical and the hydroxyl free radical are the primary active substances in the photodegradation reaction.

A Novel Synthetic 3D Interconnected Porous Carbon-Rich Graphitic Carbon Nitride for Boosting Visible Light Photocatalytic Hydrogen Production and Dye Contaminant Degradation

The use of photocatalysis to address environmental pollution and energy shortage is an attractive choice. Herein, we successfully synthesized a novel 3D interconnected porous carbon-rich g-C3N4 catalyst via facile thermal polymerization to enhance photocatalytic hydrogen production and photodegradation of dye contaminants. Enhanced hydrogen evolution (1956.23 μmol g−1 h−1) and photocatalytic RhB degradation (96.74%) efficiency were achieved with the as-obtained catalysts. Based on the photocatalytic experimental data and characterization analyses, an enhancement mechanism was proposed. The 3D interconnected porous structure endowed the g-C3N4 with numerous active sites and a large specific surface area, and the carbon modification facilitated the separation and transfer of the photoinduced charge carriers. Nanoshape engineering and the carbon-rich structure showed a synergetic effect in increasing photocatalytic performance. This study offers an applicable methodology for the exploitation of an economical catalyst to alleviate environmental pollution and energy shortages.

Designing advanced S-scheme CdS QDs/La-Bi2WO6 photocatalysts for efficient degradation of RhB.

Finding effective strategies to design efficient photocatalysts and decompose refractory organic compounds in wastewater is a challenging problem. Herein, by coupling element doping and constructing heterostructures, S-scheme CdS QDs/La-Bi2WO6 (CS/LBWO) photocatalysts are designed and synthesized by a simple hydrothermal method. As a result, the RhB degradation efficiency of the optimized 5% CS/LBWO reached 99% within 70min of illumination with excellent stability and recyclability. CS/LBWO shows improvement in the adsorption range of visible light and promotes electron-hole pair generation/migration/separation, attributing the superior degradation performance. The degradation RhB mechanism is proposed by a free radical capture experiment, electron paramagnetic resonance, and high-performance liquid chromatography-mass spectrometry results, indicating that h+ and •O2 - play a significant role during four degradation processes: de-ethylation, chromophore cleavage, ring opening, and mineralization. Based on in situ irradiated X-ray photoelectron spectroscopy, Mulliken electronegativity theory, and the work function results, the S-scheme heterojunction of CS/LBWO promotes the transfer of photogenerated electron-hole pairs and promotes the generation of reactive radicals. This work not only reports that 5% CS/LBWO is a promising photocatalyst for degradation experiments but also provides an approach to design advanced photocatalysts by coupling element doping and constructing heterostructures.

Sn(IV)porphyrin-Anchored TiO2 Nanoparticles via Axial-Ligand Coordination for Enhancement of Visible Light-Activated Photocatalytic Degradation

A visible-light-active photocatalyst, SnP/AA@TiO2, was fabricated by utilizing the coordination chemistry between the axial hydroxo-ligand in the (trans-dihydroxo)(5,10,15,20-tetraphenylporphyrinato)Sn(IV) complex (SnP) and adipic acid (AA) on the surface of TiO2 nanoparticles. The SnP center was strongly bonded to the surface of the TiO2 nanoparticles via the adipic acid linkage in SnP/AA@TiO2, as confirmed by various instrumental techniques. SnP/AA@TiO2 exhibited remarkably enhanced photocatalytic activity toward the degradation of rhodamine B dye (RhB) in aqueous solution under visible-light irradiation. The RhB degradation efficiency of SnP/AA@TiO2 was 95% within 80 min, with a rate constant of 0.0366 min−1. The high degradation efficiency, low catalyst loading and high reusability make SnP-anchored photocatalysts more efficient than other photocatalysts, such as TiO2 and SnP@TiO2.

Preparation, catalytic efficiency and mechanism of Fe3O4/HNTs heterogeneous Fenton-like catalyst

In situ anchor of Fe3O4 nanoparticles (NPs) onto the external surface of natural halloysite nanotubes (HNTs) was achieved by a simple one-pot solvothermal method. The Fe3O4/HNTs composites were characterized by XRD, SEM, TEM, FT-IR, VSM, and N2 adsorption-desorption. Characterization results showed that the magnetic Fe3O4 NPs formed tightly on the external surface of HNTs with good dispersion. Fe3O4/HNTs composites exhibited typical ferromagnetic property determined by VSM tests and could be recovered by an external magnet. Degradation experiments were conducted using the active dye RhB as the target probe to evaluate the Fenton-like catalytic efficiency of Fe3O4/HNTs composites obtained under different preparation conditions. The experimental results indicated that the degradation efficiency of RhB could reach more than 98 % within 10 min reaction time, when the initial pH was 3.5, initial RhB concentration was 100 mg L−1, H2O2 concentration was 1.96 mmol L−1, and catalyst dosage was 0.5 g L−1, realizing the rapid degradation of high concentration dye. Comparative investigations revealed that the Fenton-like catalytic efficiency of Fe3O4/HNTs for degrading high concentration RhB was much higher than that of Fe3O4 NPs. The heterogeneous Fenton-like catalytic mechanism of Fe3O4/HNTs was elucidated. Hydroxyl radicals (•OH) and superoxides radicals (•O2-) dominated the RhB degradation in the Fe3O4/HNTs-H2O2 system.

Z‐Scheme TiO2/g‐C3N4 Activation of Peroxymonosulfate to Remove Organic Pollutants: Properties and Mechanism

AbstractTiO2/g‐C3N4 hybrids (TCNs) were constructed by an ammonium salt‐assisted hydrothermal‐high temperature calcination method and used to activate peroxymonosulfate (PMS) to degrade multiple simulated pollutants. The Z‐scheme heterojunction between TiO2 and g‐C3N4 can effectively promote the separation of electron‐hole pairs and improve the photocatalytic activation effect of TCN. The degradation efficiency of RhB in the TCN1/PMS system was 92.3 %, which was only 59.8 % and 63.2 % in g‐C3N4 /PMS the g‐C3 N4/PMS system and TiO2/PMS system, respectively, after 60 min of reaction under sunlight. The TCN1‐4 sample prepared by adding (NH4)2SO4 into the precursor of TCN1 has a higher specific surface area (116.44 m2/g), which provides a better photocatalytic activation effect on PMS: the degradation efficiency of RhB in the TCN1‐4/PMS system can reach 93.9 % after 30 min, which was similar to that of the TCN1/PMS system after 60 min (92.3 %), and the reaction efficiency was doubled. Radical quenching experiments showed that free radicals (⋅OH, SO4⋅−, ⋅O2−), nonradicals (1O2) and h+ existed in the TCN1‐4/PMS reaction system.

Energy storage performance and photocatalytic activity of Diamond-like ZnCo2O4 nanostructure

Diamond-Shaped ZnCo2O4 nanostructures were synthesized using a facile sodium hydroxide-mediated hydrothermal method. The size and crystallinity of the ZnCo2O4 nanodiamond structure were tuned by simply varying the reaction time and temperatures. The specific capacitance value of 560 Fg−1 has been obtained at the scanning rate of 10 mVs−1. The internal resistance of the material is 1.6 Ω. The GCD curve also reveals the ZCO-D electrode has good charge/discharge time and superior specific capacitance. The optical behavior of the synthesized sample was studied using UV-DRS technique and the band gap was found to be ∼ 3.5 eV. The photocatalytic degradation of diamond-like ZnCo2O4 nanostructure vaule for 88 % and 70 % degradation efficiency of MV and RhB, respectively.

High performance visible light response 0D/2D MoS2QDs/BiOCl photocatalyst with synergetic effects of up-conversion and direct Z-scheme heterojunction

Constructing Z-scheme heterojunction has been regarded as a fascinating method to enhance the charge carrier separation rate and retain the high photoredox ability. In this paper, a novel 0D/2D MoS2QDs/BiOCl Z-scheme heterojunction with outstanding visible-light photocatalytic performance has been successfully prepared by a facile one-step strategy. The MoS2QDs with a diameter of 5 nm were uniformly distributed on the surface of BiOCl nanosheets. The optimized MoS2QDs/BiOCl heterojunction showed the most robust CIP and RhB degradation efficiency, which was approximately 32.2 and 44.7 times higher than that of pure BiOCl under visible light irradiation, respectively. This result can be attributed to the synergetic effects of up-conversion and direct Z-scheme heterojunction of the MoS2QDs. The optical property, morphology and surface feature of the catalyst were analyzed through the UV–vis DRS, PL, XRD, Raman, FT-IR, XPS, SEM and TEM. The study of ESR characterization and free radical capture experiments confirmed the Z-scheme heterojunction electron transfer route. Finally, a rational photocatalytic mechanism for pollutants degradation over the MoS2QDs/BiOCl heterojunctions were proposed. This study may provide a reliable strategy for the construction of Z-scheme bismuth-based heterojunction and its potential application in photocatalytic organic pollutants degradation.

TiO2 nanotube/ZnIn2S4 nanoflower composite with step-scheme heterojunction for efficient photocatalytic H2O2 production and organic dye degradation

The intellectual design of photocatalysts to advance important photocatalytic goals such as pollutant degradation and hydrogen peroxide production is challenging. In the present work, a novel TiO2 NT/ZIS heterojunction photocatalyst was synthesized by a hydrothermal method and applied for photocatalytic RhB degradation and H2O2 generation. Prepared materials were characterized by different techniques concerning structural, optical, morphological, and electrochemical properties. At the same time, the electronic-structural features and photocatalytic mechanism were profoundly investigated by combining Tauc plots, Mott-Schottky curves, XPS analysis, and scavenging test results. The TiO2 NT/ZIS heterojunction displayed the best activity in H2O2 generation of 9.78 mmol/L after 30 min, which was about 5.1, 2.1, and 1.8 times higher than those of pure P25, TiO2 NT, and ZIS samples, respectively. In addition, the RhB degradation efficiency reached 90.2% on TiO2 NT/ZIS nanocomposite after 120 min, while 18.2%, 37.4%, and 38.6% on pure P25, TiO2 NT, and ZIS, respectively. An S-scheme mechanism was suggested to model and interpret the improved photocatalytic performance of the TiO2 NT/ZIS heterojunction composite. This work provides guidance for the design, development, and application of heterostructure photocatalysts in H2O2 production.

The Photocatalytic Performance of P, Cl Doped Carboxylated Multiwalled Carbon Nanotube Modified Graphitic Carbon Nitride.

Graphitized carbonitride (g-C3N4) is widely used in CO2 reduction, hydrogen production, and degradation of toxic chemical dyes and antibiotics. It is a kind of photocatalytic material with excellent performance, and it has the advantages of being safe and nontoxic, having a suitable band gap (2.7 eV), and having a simple preparation and high stability, but because of its fast optical recombination speed and low visible light overutilization, the multifunctional application of g-C3N4 is seriously hindered. Compared with pure g-C3N4, MWCNTs/g-C3N4 have a red-shift in the visible range and a strong absorption in the visible region. Melamine and carboxylated multiwalled carbon nanotubes were used as raw materials to successfully prepare CMWCNT modified g-C3N4 doped with P, Cl by a high temperature calcination method. The effect of the addition amount of P, Cl on the photocatalytic performance of modified g-C3N4 was studied. The experimental results show that the multiwalled carbon nanotubes can accelerate the electron migration, and the doping of P, Cl elements can change the energy band structure of g-C3N4 and reduce the band gap. Through fluorescence analysis and photocurrent analysis, it is known that the incorporation of P, Cl reduces the recombination efficiency of photogenerated electron-hole pairs. In order to explore the application in the degradation of chemical dyes, the photocatalytic degradation efficiency of RhB under visible light was studied. The photocatalytic performance of the samples was evaluated by photodecomposition of aquatic hydrogen. The results showed that when the amount of ammonium dihydrogen phosphate was 10 wt %, the photocatalytic degradation efficiency was the highest, which was 21.13 times higher than that of g-C3N4.

Enhanced triboelectric degradation of organics by tuning the synergy between ferroelectric polarization and illumination

It is urgently necessary to develop efficient and environmentally friendly catalysts to solve pollution problems faced by humankind. In this work, ferroelectric Ba2-xSr3+xLaNb7Ti3O30 (x = 0, 0.2, 0.4, 0.6) (BSLNT) tungsten bronze ceramics were prepared using a high-temperature solid-phase method and applied as tribocatalysts for degradation of organics. The built-in electric field in ferroelectric BSLNT was enhanced by modulating the ferroelectric polarization and by electrical poling. The degradation results show that better ferroelectric properties of the tribocatalysts led to better the catalytic capability with 92% RhB degradation after 2 h. The further enhanced polarization of the catalyst by electrical poling can improve the degradation efficiency of RhB to 96.8% in 2 h. Under the synergistic effect of illumination and friction, the degradation efficiency of RhB after 30 min reached 95.2%. Therefore, a highly efficient ferroelectric tribocatalyst with an enhanced built-in electric field for degradation of dye wastewater was demonstrated, expanding the application of ferroelectric materials in the catalysis field.

Heterostructure charge transfer dynamics on self-assembled ZnO on electronically different single-walled carbon nanotubes

The charge transfer kinetics of the catalyst particles play a key role in advanced oxidation processes (AOP) for the complete destruction of recalcitrant and persistent contaminants in water. Here, a significant improvement in the photocatalytic performance is observed in the Single-Walled Carbon Nanotube (SWCNT)-ZnO heterostructure photocatalyst. The charge transfer dynamics and factors affecting AOP are studied using ZnO nanoparticles self-assembled onto three electronically different SWCNTs (metallic, semiconducting, and pristine) via the precipitation method, introducing a heterojunction interface. The creation of the SWCNT/ZnO heterostructure interface improves charge transfer and separation, resulting in a charge carrier lifetime of 7.37 ns. Also, surface area, pore size, and pore volumes are increased by 4.2 times compared to those of ZnO. The nanoparticles-coated face-mask fabric used as the floating photocatalyst exhibited high stability and recyclability with 99% RhB degradation efficiency under natural sunlight and 94% under UV light after the 5th cycle. The surface and crystal defects-oxygen or zinc defects/interstitials open new reaction active sites that assist in charge carrier transfer and act as pollutant absorption and interaction sites for enhanced performance. The ideal band edge positions of the valence band and conduction band favor the generation of H2O/OH•, OH·/OH, and O2/HO2• reactive oxygen species. OH• radicals are found to play a vital role in this AOP by using ethanol as an OH• scavenger.