Photoinduced Carriers Research Articles

TiO2-x-MoS2 heterostructure: A study of kinetic, thermodynamic, and scavenging agents’ effects in photodegradation

Numerous applications for photocatalysis exist in the energy and environmental sectors. In this study, a heterojunction system comprising oxygen vacancies-mediated TiO2 nanorods (TiO2-x) modified with MoS2 nanosheets (TiO2-x-MoS2) was prepared using the hydrothermal method. The photocatalytic activity of TiO2-x-MoS2 heterostructure is about 3 times higher than that of pure TiO2. The heterostructure significantly improved the photoinduced charge carrier separation efficiency, resulting in an increase in active species including ˙OH, O2˙−, and h+. Additionally, the Langmuir-Hinshelwood (L-H) model was employed to model kinetic and equilibrium data. The results of scavenging studies indicated that the photocatalytic process heavily relies on superoxide radicals. Additionally, the sensitivity of photocatalytic rates to temperature through kinetic studies based on Arrhenius and transition state models was investigated, which yielded an activation energy of 23.01 kJ/mol for the process. A positive activation entropy (ΔS = +0.017 kJ/mol) was obtained, along with positive ΔH and ΔG values, for the Rhodamine B photodegradation. This work underscores the critical role of oxygen vacancies and heterostructures in advancing wastewater treatment approaches.

Improved photoresponse performance of self-powered solar-blind UV photodetectors based on n-Si/n-Ga2O3/p-Li:NiO dual-junction

The solar-blind photodetectors (SBPDs) based on the wide-bandgap semiconductor gallium oxide (Ga2O3) exhibit significant potential for applications in military, civilian, and medical fields. Although multiple structural designs of Ga2O3-based SBPDs have been proposed, their performance typically falls short of commercial standards. However, the photoresponse speed of most self-powered PDs decreases rapidly in the solar-blind region. To address this issue, we first prepared high-quality single-crystal β-Ga2O3 films using RF magnetron sputtering, which exhibit an average transmittance exceeding 85% across the 400–800 nm range and possess a relatively smooth surface. Subsequently, a superior performance self-powered SBPD of vertical structure of n-Si/n-Ga2O3/p-Li:NiO dual-junction was fabricated, which possesses a responsivity of 0.18 mA/W, a photo-to-dark current ratio of 395, rapid rise/decay times of 132/148 ms, and a specific detectivity of 1.57 × 109 Jones at 0 V bias under 254 nm illumination. The photocurrent of the device fully recovered to its initial level after experiencing changes in ambient temperature [from room temperature (RT) to 100 °C and back to RT], demonstrating robust stability in harsh environments. In addition, the valence band structures of p-Li:NiO and n-Ga2O3 were investigated in detail using XPS, and the working mechanism of the devices was analyzed based on the Fermi level alignment. The excellent performance of PDs can be attributed to the increased depletion layer width, which generates more photogenerated carriers. Additionally, the separation and transmission of photo-induced carriers are enhanced by the superposition of a double built-in electric field. Our strategy offers a promising approach for achieving high-performance Ga2O3-based photovoltaic PDs.

LSPR-assisted W18O49/ZnO S-scheme heterojunction for efficient photocatalytic CO2N-formylation of aniline

Designing highly efficient photocatalyst for the valorization of CO2 is an ideal strategy to reduce greenhouse gas emissions and utilize solar energy. In this study, a S-scheme heterojunction photocatalyst is fabricated by solvothermal impregnation of ZnO on W18O49 for photocatalytic CO2N-formylation of aniline. The localized surface plasmon resonance effect of W18O49 improves the absorption capacity for long-wave light significantly, and the hot electrons generated in W18O49 with a high energy can migrate to the conduction band of ZnO and thus enhance the photocatalytic reduction ability. Meanwhile, the S-scheme heterojunction facilitates the separation of photoinduced charge carriers and preserves the redox ability of W18O49/ZnO composite photocatalyst. The conversion of aniline reaches 99.1% after 5 h reaction under visible light irradiation at room temperature with an N-formylaniline selectivity of 100%. A possible photocatalytic reaction mechanism is proposed. This study paves a promising way for the design of highly efficient photocatalyst and the sustainable utilization of CO2.

Targeted Electron‐Hole Separation to Decoupled Redox‐Active Sites Over a PEA2PbBr4/CeO2 P‐N Heterojunction for Enhanced Photocatalytic Oxidation

AbstractPhotocatalytic selective oxidation of C(sp3)─H bonds into valuable carbonyl compounds offers a promising approach to advance green organic synthesis and contribute to a more sustainable chemical industry. However, significant challenges remain due to the low efficiency of photocatalysts, primarily caused by insufficient charge separation and the limited ability of intermixed surface redox‐active sites to precisely capture photoinduced charge carriers. Here, a PEA2PbBr4/CeO2 (PPB/CeO2) p‐n heterojunction is designed and fabricated. Experimental characterizations and theoretical calculations reveal that a strong internal electric field (IEF) is formed at the interface within the p‐n heterojunction, which drives targeted accumulation of holes on PPB and electrons on CeO2. Importantly, CeO2 displays superior oxygen affinity facilitating O2 reduction, while PPB validates stronger adsorption and activation capability to toluene molecule promoting C─H bond dissociation. In this context, the photoinduced electrons and holes are directionally separated and transported to the decoupled reduction and oxidation sites in the PPB/CeO2, thereby significantly accelerating the aerobic oxidation of C(sp3)─H bonds. Toward photocatalytic oxidation of model substrate toluene, the optimized PPB/CeO2‐5% composite exhibits a toluene conversion rate of 10 050 µmol g−1 h−1, which is nine times enhanced in comparison with blank PPB (1160 µmol g−1 h−1).

Facile Synthesis of Bandgap-Engineered N-Doped MgO/g-C3N4 Nanocomposites for Enhanced Sunlight-Driven Photocatalytic Degradation of Organic Dyes

This study tests the theory of using a p-n junction to inhibit the recombination of photo-generated electrons and holes in N-MgO/g-C3N4 for the photocatalytic degradation of methylene blue (MB) dye. While the use of n-type semiconductor junctions with g-C3N4 for bandgap narrowing is well-studied in dye degradation, this research explores the innovative application of nitrogen (N)-doped MgO to create a p-type junction with n-type g-C3N4. The N-MgO/g-C3N4 nanocomposites were designed and synthesized to leverage both the bandgap narrowing effect and the formation of a p-n junction. The results demonstrate that these nanocomposites can effectively degrade MB dye under sunlight, achieving over 90% degradation efficiency with a bandgap of 2.63 eV. Under high pH conditions, the degradation efficiency further increased to 94%. The enhanced photocatalytic activity of the N-MgO/g-C3N4 composite is attributed to the formation of a heterojunction, which facilitates efficient separation and transmission of photo-induced charge carriers. This study discusses the detailed mechanism of this enhanced activity, emphasizing the role of the p-n junction in promoting effective charge separation and transfer, thereby improving the photocatalytic performance under sunlight.

Targeting active sites nickel-porphyrin over BiOBr nanosheets with excellent charge separation for accelerated photoreduction reactions

The energy crisis and environmental pollution severely constrained the sustainable development of society. Herein, nickel-porphyrin active sites have been integrated over BiOBr for enhanced photocatalytic CO2 reduction and Cr(VI) removal. The optimized NiTMCPP/BiOBr-2 photocatalyst exhibits CO generation rate of 14.14 μmol g−1 under irradiation for 5h, which is around 2 times compared with BiOBr. Meanwhile, Cr(VI) removal efficiency over NiTMCPP/BiOBr-2 is 97.72% under visible light irradiation for 40min, which shows enhanced photoreduction ability compared with BiOBr (77.31%). Numerous experimental results indicate that the improved photocatalytic activity for NiTMCPP/BiOBr-2 is mainly owing to the enhanced transport efficiency of photoinduced carriers after the loading of Ni-porphyrin. Especially, the central Ni2+ active site of porphyrin can accept excitation electrons, thus enhancing photoreduction performance. Furthermore, the mechanisms for photocatalytic CO2 and Cr(Ⅵ) reduction were further discussed via in-situ FT-IR and capture experiments. This work gives a promising way to design hybrid photocatalysts for energy conversion and environmental treatment.

Constructing robust Z-type BiOBr/Br-doped g-C3N4 heterojunctions for visible light-assisted photocatalytic decontamination of norfloxacin

In order to remediate the environment in a green way, the development of new and effective photocatalytic heterojunctions has received great attention from researchers in recent years. Herein, we assembled BiOBr-decorated Br-doped g-C3N4 (BiOBr/BrCN) hybrid heterojunctions in different percentages (BiOBr content = 5–30 wt%) to achieve effective photocatalytic heterojunctions for visible-light-prompted degradation of antibiotic norfloxacin (NOR), in which reducing the photocarriers recombination rate. Obviously, BiOBr/BrCN composites endorsed greater photodecomposition performance of NOR under visible-light illumination. The 10 wt%BiOBr/BrCN photocatalyst decomposed 95.5 % of NOR in 1.5 h, which are approximately 2.5 and 1.7 times of enhancement compared with BrCN and BiOBr, respectively. The enlarged response to visible-light and the efficient separation of photo-induced carriers in the developed Z-system heterojunction between BiOBr and BrCN were behind the boosted photocatalytic activity. Besides, the trapping experiments demonstrated that both •O2− and h+ species take significant roles in the degradation of NOR antibiotic, which supports the proposed mechanism. In addition, the degradation efficiency displays an insignificant decrease after the fifth cycle, indicating that the synthesized BiOBr/BrCN photocatalyst system has a great stability for the practical applications.

Enhancing Internal Electric Field of Metal-Free Donor-Acceptor Conjugated Photocatalysts for Efficient Photocatalytic Degradation of Tetracycline and CO2 Reduction.

Constructing alternating donor-acceptor (D-A) units within g-C3N4 represents an effective strategy for enhancing photocatalytic performance through improved charge carrier separation while concurrently addressing energy shortages and facilitating wastewater remediation. Here, a series of D-A-type conjugated photocatalysts (CNBTC-X) are prepared using g-C3N4 as an acceptor unit and different masses of 5-bromo-2-thiophenecarboxaldehyde (BTC) as a donor unit by a one-step thermal polymerization. CNBTC-50 presents higher photocatalytic properties for CO2 reduction coupled with tetracycline (TC) removal than those of g-C3N4, CNBTC-10, CNBTC-30, and CNBTC-70. The introduction of the unique electron-donor-acceptor structure effectively drives the separation and transfer of photoinduced carriers while reducing the internal carrier transfer hindrance. Photocatalytic experiments reveal that the CNBTC-50 photocatalyst achieves up to 94.6% TC removal under visible light irradiation conditions. Compared with that of the pristine g-C3N4, the photocatalytic degradation reaction rate constant of CNBTC-50 is significantly increased by about 3.87 times. The study examines the influence of various reaction parameters on degradation activity, including catalyst concentration, pH, and TC concentration. Additionally, LC-MS is utilized to perform a comprehensive analysis of the intermediates and pathways involved in TC degradation. Furthermore, CNBTC-50 demonstrates remarkable photocatalytic CO2 reduction activity, achieving rates of 20.83 μmol g-1 h-1 (CO) and 9.36 μmol g-1 h-1 (CH4), which are 10.68 and 5.98 times more efficient than those of g-C3N4, respectively. This work aims to offer valuable guidance for the rational design of nonmetal D-A-structured catalysts and effectively integrates reaction systems to couple CO2 reduction with antibiotic removal.

Synergistic effect between amino functional group and graphene oxide in selective photocatalytic CO2 reduction to formic acid

Carbon dioxide (CO2) reduction to useful possible chemicals is of great significance to energy supply, while formic acid is one of the most desirable product among the many other chemicals. In this study, a novel reduced graphene oxide (rGO) coupled doped TiO2 with NH2-MIL-125(Ti)(TiM) composite photocatalysts TiO2@rGO@TiM was designed by using a solvent-thermal method to facilitate the photocatalytic CO2 reduction to formic acid under the visible light. Benefiting from the special structure of TiO2@rGO@TiM, up to a rate of 113 µmol•g−1•h−1 of formic acid was produced in a photochemical process, which is four times greater than that of pure TiO2 and TiM without any sacrificial agent. The results of structure and photoelectrochemical characterization demonstrated that the enhanced production of formic acid was attributable to the synergistic effect generated by the incorporation of the amino functional group and reduced graphene oxide, resulting in the effective photo-induced carrier spatial segregation and transfer and improving the catalytic activity.

Enhanced Charge Transfer in Poly(Heptazine Imide) Synergistically Induced by Donor-Acceptor Motifs and Ohmic Junctions for Efficient Photocatalytic CO2 Reduction.

Poly(heptazine imide) (PHI) has received widely interest in the photocatalytic CO2 reduction due to its good crystallinity and complete in-plane structure. However, its poor photo-induced carrier separation and migration efficiency and insufficient active sites results in undesirable photocatalytic CO2 reduction performance. Herein, we designed and constructed a novel ohmic junction photocatalyst by integrating melamine edge-modified PHI (mel-PHI) with extended π-conjugated system with TiN (TiN/mel-PHI) for enhancing the photocatalytic CO2 reduction activity. Strikingly, the photocayalytic CO2 reduction yield of the optimal TiN/mel-PHI is 62.64 µmol·g-1·h-1, which is 5.6 and 2.8 times higher than PHI (11.26 µmol·g-1·h-1) and mel-PHI (22.32 µmol·g-1·h-1), respectively. The superior photocatalytic CO2 reduction activity is attributed not only to the formation of D-A structure by the introduction of melamine, which extends the π-conjugation system, alters the electronic structure of PHI, and accelerates the charge separation and migration, but also to the induced internal electric field by ohmic junction further enhances the charge separation and migration efficiency. Meanwhile, the synergistic effect of mel-PHI and TiN enriched the electron number of TiN, reducing the CO2 reduction potential. This work highlights the synergistic enhancement of charge transfer between D-A motifs and ohmic junctions, confirming their potential in optimizing photocatalysts.

Ultrafast terahertz conductivity in epitaxial graphene nanoribbons: an interplay between photoexcited and secondary hot carriers

Abstract Optical pump-terahertz probe spectroscopy has been used to investigate ultrafast photo-induced charge carrier transport in 3.4 µm wide graphene ribbons upon scaling the optical pump intensity. For low pump fluences, the deposited pump energy is rapidly redistributed through carrier–carrier scattering, producing secondary hot carriers: the picosecond THz photoconductivity then acquires a negative sign and scales linearly with an increasing pump fluence. At higher fluences, there are not enough equilibrium carriers able to accept the deposited energy, directly generated (excess) carriers start to contribute significantly to the photoconductivity with a positive sign leading to its saturation behavior. This leads to a non-monotonic variation of the carrier mobility and plasmonic resonance frequency as a function of the pump fluence and, at high fluences, to a balance between a decreasing carrier scattering time and an increasing Drude weight. In addition, a weak carrier localization observed for the polarization parallel to the ribbons at low pump fluences is progressively lifted upon increasing the pump fluence as a result of the rise of initial carrier temperature.

Cu/S Co-anchoring junction boosted the photogenerated carrier separation efficiency in g-C3N5 for enhanced H2 evolution

C3N5 is emerging as an important visible light catalyst because of its narrow band gap, nontoxicity and thermal stability. Herein, sulfur-doped g-C3N5 (SCN) was prepared by copolymerization of thioacetamide (TAA) and 3-amino-1,2,4-triazole (3-AT). Then copper nanoparticles (Cu NPs) were anchored onto the SCN framework, resulting in the formation of Cu/SCN. It was found that the average H2 production rate of SCN and Cu/SCN was 0.76 and 1.34 mmol g−1 h−1, which was much higher than that of C3N5, respectively. Acting as a new active spots, sulfur doping effectively reduces the band gap of g-C3N5, and the formation of S-Cu bonds further creates an efficient electron transport pathway. As a result, Cu/SCN possesses a broader visible light absorption spectrum, stronger reduction capability, and greater efficiency in photo-induced carrier separation and transfer. Therefore, this work introduces a novel strategy for design of high efficiency photocatalytic H2 evolution carbon nitride through non-noble metal and sulfur anchoring junction.

Interfacial coupling mechanism for efficient degradation of tetracycline by heteroatom iodine (I)-doped BiOBr under visible light: Efficacy and driving force

Studies on photocatalytic materials frequently focus on two pivotal metrics: the generation and separation capabilities of photoinduced charge carriers. In this context, we developed a diverse range of BiOBrxI1-x solid solutions (x = 1, 0.75, 0.50, 0.25, 0) via a simple room-temperature synthesis. The BiOBr0.75I0.25 solid solution demonstrated a remarkable degradation ability (up to 88.4 %) for tetracycline (TC) within a span of 60 min under visible light. This efficiency was attributed to enhanced light absorption within the visible region and improved segregation of photoinduced charges. A systematic study was performed to determine the influence factors of the degradation efficiency and the roles of different reactive species. A comprehensive photocatalytic mechanism was proposed on the basis of the results of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. Finally, theoretical calculations were integrated with liquid chromatography-mass spectrometry (LC-MS) results to propose a degradation pathway for BiOBr0.75I0.25.

A superlattice interface and S-scheme heterojunction for ultrafast charge separation and transfer in photocatalytic H2 evolution

The rapid recombination of photoinduced charge carriers in semiconductors fundamentally limits their application in photocatalysis. Herein, we report that a superlattice interface and S-scheme heterojunction based on Mn0.5Cd0.5S nanorods can significantly promote ultrafast charge separation and transfer. Specifically, the axially distributed zinc blende/wurtzite superlattice interfaces in Mn0.5Cd0.5S nanorods can redistribute photoinduced charge carriers more effectively when boosted by homogeneous internal electric fields and promotes bulk separation. Accordingly, S-scheme heterojunctions between the Mn0.5Cd0.5S nanorods and MnWO4 nanoparticles can further accelerate the surface separation of charge carriers via a heterogeneous internal electric field. Subsequent capture of the photoelectrons by adsorbed H2O is as fast as several picoseconds which results in a photocatalytic H2 evolution rate of 54.4 mmol·g−1·h−1 without any cocatalyst under simulated solar irradiation. The yields are increased by a factor of ~5 times relative to control samples and an apparent quantum efficiency of 63.1% at 420 nm is measured. This work provides a protocol for designing synergistic interface structure for efficient photocatalysis.

Fe-N Co-Doped BiVO4 Photoanode with Record Photocurrent for Water Oxidation.

Bismuth vanadate (BVO) ranks among the most promising photoanodes for photoelectrochemical (PEC) water splitting. Nonetheless, slow charge separation and transport, besides the sluggish water oxidation kinetics, are key barriers to its photoefficiency. Here, we present a co-doping strategy that significantly improves the charge separation performance of BVO photoanodes. We found that, under standard one sun illumination, the Fe-N co-doped BVO photoanode (Fe-N-BVO) by N-coordinated Fe precursor reaches a record photocurrent density of 7.01 mA cm-2 at 1.23 V vs RHE after modified a surface co-catalyst (FeNiOOH), and exhibits an outstanding stability. By contrast, much lower photocurrent density is obtained for the N-doped, Fe-doped and Fe/N-doped BVO photoanode with separated N and Fe precursors. The detailed experimental characterizations show that the high activity of the Fe-N co-doped BVO photoanode is attributed to the enhanced photo-induced bulk charge separation, as well as the accelerated surface water oxidation kinetics. XPS, EXAFS and DFT calculations clearly show that, instead of formation of deep trapping state in the individually doped BVO, the co-doping of Fe-N into BVO generates Fe-based electronic states just below the bottom of conduction band and N-derived states just above the top of valence band. Such modulations in electronic structure enable the efficient trap of the electrons and holes to enhance the separation of photo-induced carriers, but hinder the charge recombination originated from the deep trapping sites.

Direct photoelectrochemical detection of ethanol in complex biological sample

The development of advanced photoelectrochemical (PEC) technology for the direct detection of ethanol in complex biological sample, has become a hot topic. However, the photo-active nanomaterials, which could generate the photo-induced carriers under illumination, are susceptible to biofouling and interference in complex bio-matrices. In this work, the silica nanochannel-protected TiO2 nanomaterials was reported for the first time that enables the direct sensing of ethanol in real fruits and untreated whole blood. The modification of SNC enhanced the sensitivity of ethanol detection by promoting light absorption, electron-hole separation, and surface reaction rate of photo-active materials. Meanwhile, the biofouling macromolecules and interference signals can be effectively excluded due to the hydrophilic properties, size, and electrostatic exclusion of nanochannels. As a result, without any complex sample pretreatments, the proposed PEC sensor can be directly immersed in complex biological samples for ethanol detection, exhibiting a broad linear range (1.775 μM-20 mM) and a low detection limit (1.2 μM), as well as excellent reproducibility and stability. This work paves a new path for PEC sensors in real biomedical applications.

Novel Anodic TiO2 Synthesis Method with Embedded Graphene Quantum Dots for Improved Photocatalytic Activity

Photocatalytic degradation of pollutants have a high potential for sustainable and renewable uses. TiO2 is a widely studied photocatalyst due to its high chemical and photochemical stability and wide range of applications. However, the wide band gap and low capacity of photo-induced charge separation provide lower catalytic activity; thus, improvement of these properties must be found. The doping of TiO2 with other elements, such as carbon nanoparticles (CNP) in a quantum dot form, offers a promising pathway to improve the aforementioned properties. In addition, in situ doping methods should be investigated for practical scalability, as they offer the advantage of integrating dopants directly during material synthesis, ensuring a more uniform distribution and better interaction between the dopant and the host material, in turn leading to more consistent photocatalytic properties. Current technologies primarily involve nanoparticle combinations. This work focuses on the development of a novel in situ synthesis methodology by the introduction of three different graphene-based quantum nanodots into anodic TiO2 and the following investigation of structural, morphological, and photocatalytic properties. Results indicate that the introduction of CNP allows for the shift of a set of parameters, such as the optical band gap, increased photo-induced charge carrier density of TiO2/CNP composite, and, most importantly, the change of crystalline phase composition depending on added CNP material. Research indicates that not only a higher concentration of added CNP enhances higher photocatalytic activity as tested by the degradation of methylene blue dye, but also the type of CNP determines final crystalline phase. For the first time brookite and rutile phases were obtained in anodic titania synthesized in inorganic electrolyte by introducing hydrothermally treated exfoliated graphene.

Application of NiS modified WS2/TiO2 heterostructure in photocathodic protection

Stainless steel, as a popular corrosion resistant material, is still vulnerable to pitting corrosion in the marine environment. Therefore, in order to ensure the safety of stainless steel in the marine environment, it is necessary to implement corresponding protective measures. Titanium dioxide (TiO2), as an N-type semiconductor with excellent photoelectric properties, is widely used in the field of cathodic protection. However, as a photogenerated cathodic corrosion protection material, TiO2has the disadvantages of low conductivity and high carrier recombination rate. Therefore, WS2and NIS were introduced in this paper to modify it. TiO2/WS2/NiS (TWN) composites with Type-Ⅱ heterojunction structure were prepared by hydrothermal method and titration method. The results reveal TWN5 showed the best photoelectrochemical (PEC) performance, and the photocurrent density was 69% higher than that of a pure TiO2photoanode, and the photochemical and photocathodic protection performance was significantly better than that of pure TiO2. Under simulated ocean conditions, the self-corrosion potential of 304ss combined with TW5 and TWN5 photoanodes is reduced to -0.64 V and -0.7 V, respectively. The main reason is that the contact surfaces of WS2and TiO2formed a Type II heterostructure, which accelerates the separation and diffusion processes of photoinduced carriers. In addition, the plasmon resonance effect of NiS improves the ability to absorb visible light, and the metallic-like feature of NiS also promotes charge separation.

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.

Spherical magnetic MgO-CeO2-Fe3O4@JB heterojunction for enhanced photodegradation of pesticide and complex anionic dyes: Understanding the degradation process and diverse water systems

Clothianidin (CLO) is a widely utilized pesticide recognized as an emerging pollutant capable of contaminating surface and subsurface water sources. Utilizing nanoparticles for photodegradation is a very ecological and cost-effective method for water treatment. This study involves the creation of a MgO-CeO2-Fe3O4@JB (Jute-Biochar) heterojunction with a mesoporous structure using hydrothermal process. The purpose of this design is to explore its potential for photocatalytic applications. PXRD (Powder X-ray Diffraction), FTIR (Fourier Transform Infrared), UV–DRS (Ultraviolet–Visible Diffuse Reflectance Spectroscopy), PL (Photoluminescence), TEM (Transmission Electron Microscopy), EDX (Energy Dispersive X-ray), XPS (X-ray Photoelectron Spectroscopy), VSM (Vibrating Sample Magnetometry), BET (Brunauer Emmett Teller), and SEM (Scanning Electron Microscopy) analysis confirmed the formation of a mesoporous MgO-CeO2-Fe3O4@JB heterojunction with preferred interface between MgO, CeO2, and Fe3O4 phases, extending the light-absorption insights to 700 nm. The photocatalytic performance of MgO-CeO2-Fe3O4@JB heterojunction was evaluated under visible-light using CLO as the target molecule. The degradation performances of CLO on MgO-CeO2-Fe3O4@JB were determined to be 95.24 ± 1.18 % after 35 min of exposure to light. The calculated rate constants for the degradation of CLO in presence of light using the MgO-CeO2-Fe3O4@JB composite were determined to be 0.0924 min−1. Furthermore, two complex dyes, Niagara Blue (NB) and Reactive Red (RR), photodegrade to 99.45 ± 1.24 % and 97.23 ± 1.41 % within 25 and 30 min, respectively. The excellent photocatalytic characteristics of the MgO-CeO2-Fe3O4@JB heterojunction were suggested to be primarily caused by the larger photo-response, aligned band-structure, and useful use of the photo-induced charge carriers of the photocatalyst. In addition, the recycling experiments have verified the exceptional photostability of the MgO-CeO2-Fe3O4@JB photocatalyst due to incorporation of nanoparticles into the biochar matrix. This leads to a synergistic mechanism for effectively eliminating these pollutants.