Heterojunction Nanocomposites Research Articles

Engineering Heterostructured Piezoelectric Nanorods with Rich Oxygen Vacancy‐Mediated Piezoelectricity for Ultrasound‐Triggered Piezocatalytic Cancer Therapy

AbstractUsing piezoelectric bionanomaterials to promote the generation of reactive oxygen species (ROS) is being increasingly recognized in ultrasound (US)‐triggered tumor treatments. The mechanism underlying this innovative treatment involves US irradiation, which activates the built‐in electric field (BIEF) and induces energy‐band bending in piezoelectric materials (PEMs). In this study, Sr0.5Ba0.5Nb2O6 (SBN) nanorods (NRs) are synthesized using a molten salt method. Subsequently, oxygen‐vacancy (OV)‐rich SBN/Sr2Nb2O7 (SBN/SNO) heterojunction nanocomposites (NCs) are fabricated via H2 annealing of the SBN NRs. The engineering strategy focused on enhancing ROS generation, thereby augmenting the piezoelectric catalytic activity of the NCs. This configuration ensures that the BIEF and heterojunction‐induced field act synergistically to provide a sustained driving force for the separation of electron‐hole (e−‐h+) pairs. Importantly, the OVs on the surfaces of the H2‐annealed SBN NRs create electron‐rich sites, which substantially enhance their piezocatalytic capabilities. In vitro and in vivo analyses of hepatocellular carcinoma (HCC) models demonstrate the significant cytotoxic and tumor‐inhibitory capabilities of this rich OV‐mediated sonopiezoelectric therapy (SPT) and illustrate its potential as a promising therapeutic approach against cancer.

Ultrasonic-driven degradation of organic pollutants using piezoelectric catalysts WS2/Bi2WO6 heterojunction composites

Water pollution has been made worse by the widespread use of organic dyes and their discharge, which has coincided with the industry's rapid development. Piezoelectric catalysis, as an effective wastewater purification method with promising applications, can enhance the catalyst activity by collecting tiny vibrations in nature and is not limited by sunlight. In this work, we designed and synthesized intriguing WS2/Bi2WO6 heterojunction nanocomposites, investigated their shape, structure, and piezoelectric characteristics using a range of characterization techniques, and used ultrasound to accelerate the organic dye Rhodamine B (RhB) degradation in wastewater. In comparison to the pristine monomaterials, the results demonstrated that the heterojunction composites demonstrated excellent degradation and stability of RhB under ultrasonic circumstances. The existence of heterojunctions and the internal piezoelectric field created by ultrasonic driving work in concert to boost catalytic performance, and the organic dye's rate of degradation is further accelerated by the carriers that are mutually transferred between the composites.

Photo-Fenton Degradation of Tetracycline and Photoelectrochemical Properties of ZnFe2O4@ZnWO4 Heterostructure Composite Coupling.

Problems such as bacterial resistance caused by tetracycline antibiotics pose a serious threat to human production and life and ecosystems. We prepared ZnFe2O4@ZnWO4 heterojunction nanocomposites using hydrothermal and coprecipitation methods. The micromorphology, structure, and photoelectrochemical properties were analyzed. In combination with the presence of H2O2, the photo-Fenton activity of the antibiotic tetracycline at high concentration was tested under visible light irradiation, and its catalytic mechanism was investigated. The results showed that the composition of the composite heterojunction improved the catalytic activity of the catalyst. At a pollutant concentration of 50 mg L-1 and pH 5, 30% ZnWO4/ZnFe2O4 degraded 92.1% of tetracycline in 60 min with a degradation rate of 0.0295 min-1, which was 6.7 times higher than that of pure ZnFe2O4. The results of free radical trapping experiments and electron spin resonance techniques indicated that hydroxyl radical (•OH) and superoxide radical (O2-) played important roles in the photo-Fenton degradation of tetracycline. Notably, the catalyst maintained a high degradation rate (80%) after five cycles. ZnFe2O4 introduced in this article may provide a promising strategy for achieving strong light absorption and is authoritative in meeting future environmental requirements.

Exploring silver oxide-loaded yttrium vanadate nanocomposite for visible-light-driven photooxidation of ciprofloxacin antibiotic in water

As a sooner or later risk, antimicrobial resistance due to the overuse of antibiotics is considered a nightmare facing humankind. The visible-light mineralization of antibiotic waste over nanoceramic photocatalysts is an innovative expectant method. Concerning this, nanostructured yttrium orthovanadate (YVO4) is grown via an adapted sol-gel process tracked by loading of 1.0∼4.0 wt.% of silver oxide (Ag2O) to form heterojunction nanocomposite of Ag2O/YVO4. The as-prepared heterostructures were applied for visible-light photoelimination of ciprofloxacin (CF) in water. The presence of Ag2O has enhanced both light absorbance and photogenerated carrier separation of YVO4. The 3.0 to 4.0 wt.% loading of Ag2O designated the thinnest bandgap of 2.4 eV regardless of the minor decrease in their specific surface areas from 220 in bare YVO4 to 168 m2 g‒1 for 3.0% Ag2O/YVO4. The complete mineralization of CF over 3.0% Ag2O/YVO4 was achieved after 60 min of light illumination at an optimized dose of 1.6 mg mL‒1 and a reaction rate constant of 5.41×10‒2 min–1. This improved photocatalyst has also a recyclable ability of ∼95% of its initial photoactivity after the fifth experimental run. Therefore, the augmented light harvesting, surface texture, as well as superb carrier separation represent a key role in the performance of Ag2O/YVO4.

Hydrothermally synthesized ZnFe2O4/ZnO heterojunction nanocomposites for enhanced RB dye degradation via Z-scheme photocatalysis

ZnFe2O4/ZnO nanocomposites with 1:1, 1:2, 1:3 and 1:4 wt ratios synthesized by hydrothermal method are used as a photocatalyst to degrade Rose Bengal (RB) dye. For structural investigation X-ray diffraction (XRD) and Fourier transform Infrared (FTIR) was performed. The presence of both phases corresponding to ZnFe2O4 and ZnO in XRD suggests the successful formation of a nanocomposite. Value of crystallite size varies from 25.01 nm to 18.61 nm for 1:1 to 1:4 nanocomposite. Almost spherical morphology of nanocomposite obtained through High-resolution transmission electron microscopy (HRTEM). FTIR demonstrated Zn–O and Fe–O bonds in as synthesized samples. Also, X-ray photoelectron spectroscopy (XPS) is used to detect the presence of Fe2+, Zn2+ and O2− ions in synthesized nanocomposites. In UV-DRS, values of band gap vary from 1.73 to 1.88 eV in nanocomposite as the weight ratio of ZnO increases. The formation of heterojunction is responsible for enhancing electron hole mobility. Due to this enhancement, degradation efficiency of 88% is achieved in 90 min irradiation of UV light by ZnFe2O4/ZnO (1:4) nanocomposites for RB dye followed Z-scheme mechanism. Also, the magnetization value of different nanocomposites changes from 0.9 to 0.1 emu/g. Magnetization nature is responsible for separating the catalyst from the reaction mixture after use. So, the nanocomposite can be reused which maintains the green protocol in the environment. ZnFe2O4/ZnO nanocomposite with 1:4 wt ratio can be reused up to 5 cycles. The formation of such nanocomposites can offer unique properties and advantages by combining the characteristics of both materials can lead to enhanced functionalities suitable for various applications such as catalysis, sensors, and magnetic devices.

Tribological properties of ternary heterojunction nanocomposites with MoS2 as the main body are enhanced

g-C3N4 has a strong C-N covalent bond within the monolayer and a weak van der Waals force between the lamels, which enables it to have similar lubrication properties to other two-dimensional layered materials. In this study, a new type of g-C3N4/MoS2/ZnS heterogeneous nanocomposites was prepared by a one-step hydrothermal method XRD, SEM, FI-IR, and other methods were used to systematically study it. Furthermore, a ball-on-disk tribometer extensively examined the tribological behavior of g-C3N4/MoS2/ZnS heterojunction in pure oil. The relationship between applied load and rotational speed on performance is also revealed. Compared with g-C3N4 and g-C3N4/MoS2 nanocomposites, g-C3N4/MoS2/ZnS has better frictional properties. It is worth noting that when g-C3N4/MoS2/ZnS is in the base oil mass ratio at 1.0 wt.%, the friction coefficient is reduced by 49%. In addition, g-C3N4/MoS2/ZnS ternary heterojunction exhibits better tribological properties than g-C3N4/MoS2/ZnS mixture, expanding their practical applications in industry and agriculture.

Facile fabrication of 3D-α-Fe2O3@2D-g-C3N4 heterojunction composite materials: Effect of iron oxide loading on the electrochemical performance

Designing heterojunction nanocomposites is crucial for optimizing supercapacitor electrodes. This study addresses the challenge by introducing a facile synthesis method for creating 3D-α-Fe2O3@2D-g-C3N4 heterojunctions through a bulk carbon nitride-assisted hydrothermal process. During this process, the growth of ferric oxide particles coincides with the exfoliation and deposition of carbon nitride, leading to simultaneous structural changes in both iron oxide and carbon nitride phases. The resulting composite's properties strongly correlate with the iron oxide loading. Comprehensive characterization using XRD, FTIR, SEM-EDAX, XPS and TEM identified three distinct structures for α-Fe2O3/g-C3N4 composites based on iron oxide loading: low, medium, and high. The medium-loaded sample demonstrated superior electrochemical performance, attributed to better interfacial contact and the formation of 3D-Fe2O3@2D-g-C3N4 heterojunctions. This composite, with an optimized 22 wt% iron oxide loading, exhibited a maximum specific capacitance of 925.1 Fg−1 at 5 mVs−1 and 498.6 Fg−1 at 6 Ag−1 in charge-discharge analysis, with stable performance over 2000 cycles. Overall, this research presents an enhanced hydrothermal method for facile preparation of effective α-Fe2O3/g-C3N4 heterojunction materials.

Solar-driven Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 heterojunction for efficient degradation of organic pollutants: Insights into adsorption mechanism, charge transfer and degradation pathway

Actualizing controllable construction of efficient heterojunction nanocomposites remains a challenge in the field of photocatalytic water remediation, which can be got over through exploiting in-situ attachment approaches between different semiconductors. Based on this, we successfully fabricated a unique separable Z-scheme Bi6O5(OH)3(NO3)5(H2O)3/Bi2WO6 (BON/BW) nanoflowers by an in-situ growth strategy. The profitable photogenerated carriers transfer mediated by Z-scheme heterojunction greatly accelerated the generation of •O2– and •OH. The strong adsorption of 4-nitrophenols (4-NP) with parallel configuration on side Bi2WO6 in BON/BW nanocomposites also provides great convenience for subsequent degradation steps. By optimizing multiple steps in the photocatalytic reaction process, BON/BW showed far superior photodegradation performance compared to single components. The causes and consequences of 4-NP photodegradation were explored through LC-MS tests, theoretical calculations, and toxicity analysis, and a green and safe degradation pathway was proposed. More experiments have confirmed that the synthesized BON/BW composites also have excellent degradation ability against other pollutants under sunlight, demonstrating excellent universality. With any luck, the logical design of heterojunction photocatalysts for effective photocatalytic water remediation should be aided by this study.

Heterojunction-Based Photocatalytic Degradation of Rose Bengal Dye via Gold-Decorated α-Fe2O3-CeO2 Nanocomposites under Visible-Light Irradiation

Developing photocatalytic nanomaterials with unique physical and chemical features using low-cost and eco-friendly synthetic methods is highly desirable in wastewater treatment. In this work, the magnetically separable α-Fe2O3-CeO2 nanocomposite (NC), with its respective metal oxides of α-Fe2O3 and CeO2 nanoparticles, was synthesized using a combination of hexadecyltrimethylammonium bromide (CATB) and ascorbic acid via the hydrothermal method. To tune the band gap, the heterojunction nanocomposite of α-Fe2O3-CeO2 was decorated with plasmonic Au nanoparticles (Au NPs). The various characterization methods, such as FTIR, UV-vis DRS, XRD, XPS, TEM, EDX, SEM, and PL, were used to determine the properties of the materials, including their morphology, elemental composition, optical properties, band gap energy, and crystalline phase. The nanocomposite of α-Fe2O3-CeO2@Au was utilized to remove Rose Bengal (RB) dye from wastewater using a photocatalytic technique when exposed to visible light. A comprehensive investigation of the impact of the catalyst concentration and initial dye concentration was conducted to establish the optimal photodegradation conditions. The maximum photocatalytic efficiency of α-Fe2O3-CeO2@Au (50 mg L−1) for RB (20 ppm) dye removal was found to be 88.9% in 120 min under visible-light irradiation at a neutral pH of 7 and 30 °C. Various scavengers, such as benzoquinone (BQ; 0.5 mM), tert-butyl alcohol (TBA; 0.5 mM), and ethylenediaminetetraacetic acid (EDTA; 0.5 mM), were used to investigate the effects of different free radicals on the photocatalytic process. Furthermore, the reusability of the α-Fe2O3-CeO2@Au photocatalyst has also been explored. Furthermore, the investigation of the potential mechanism demonstrated that the heterojunction formed between α-Fe2O3 and CeO2, in combination with the presence of deposited Au NPs, led to an enhanced photocatalytic efficiency by effectively separating the photogenerated electron (e−)–hole (h+) pairs.

Boosting solar-driven photocatalytic degradation of organic contaminants and bacterial deactivation using marigold- like Cu2O decorated g-C3N4 nanocomposite

Keeping the high efficiency in designing photocatalysts in view, the present work was aimed at the development of a heterojunction photocatalyst with boosted efficiencies, both for degradation of organic contaminants and bacterial deactivation. Heterojunction nanocomposites of g-C3N4 (GCN) and Cu2O (Cu2O /GCN-5 %, Cu2O /GCN-15 %, Cu2O/GCN-25 %, and Cu2O /GCN-50 %) were prepared by hydrothermal method and their photocatalytic performance was evaluated. XPS result confirms the surface chemical composition of nanocomposite and consistent with EDX analysis. The BET studies of Cu2O/GCN −25 % nanocomposite reveals the larger specific surface area (128.10 m2/g), compared to intact Cu2O, which facilitates more active sites on the surface. The optical bandgap energy (2.39 eV-2.58 eV) is tuned towards the visible region by loading g-C3N4 in marigold-like Cu2O. The efficient charge transfer betwixt marigold-like Cu2O and g-C3N4 was demonstrated in PL, CV, and EIS analysis. The Cu2O/GCN-25 % nanocomposite exhibits superior photocatalytic activity towards Aniline blue dye (86.4 %) and β-lactam antibiotic amoxicillin (79 %) under 100 min of sunlight irradiation. HPLC analysis further confirmed the degradation and disintegration of Amoxicillin. The probable photocatalytic mechanism was proposed and tested through a radical scavenger experiment. It was found that ●OH radicals significantly take part in the photodegradation. In addition, the bactericidal activities of Cu2O/GCN-25 % nanocomposite was determined. The highest bactericidal activity was observed for Bacillus subtilis (26 mm). Hence, the marigold-like Cu2O/GCN-25 % nanocomposite is a feasible material for the degradation of dyeing and pharmaceutical industrial effluents as well as bacterial growth inhibition.

In-situ fabrication of MoO2/MoxC heterojunction on rodlike carbon-coated zirconia for enhanced oxidative desulfurization of fuel oils

Electronic structure of catalysts is of great importance in redox reactions. Virtually, fabricating Mo-based heterojunction nanocomposites and elucidating their role in the nature of synergic effect between Mo compounds hold the key to promoting the electron transfer and eventually improving oxidative desulfurization (ODS) performances. Herein, the molybdenum dioxide/molybdenum carbides (MoO2/MoxC) heterojunction was in situ dispersedly immobilized on a rodlike N-doped carbon (NC)-coated zirconia (ZrO2) via a facile annealing route employing phosphomolybdic acid (PMo12)-loaded Zr(IV) porphyrinic metal–organic framework (MOF-545) (i.e. PMo12@MOF-545) as a precursor. The optimized catalyst (MoO2/MoxC@NC@ZrO2) exhibits outstanding oxidative desulfurization (ODS) activities for fuel oil with sulfur content in a wide range of 200～4000 ppm. It is indicated that the extraordinary ODS activity of MoO2/MoxC@NC@ZrO2 significantly stems from the accelerated electron transfer by the MoO2/MoxC heterojunction, the strong electron-donating effect of NC layer, and abundant active sites from the extremely dispersed Mo compounds realized by both NC and ZrO2. The ODS reaction is elucidated by the •OH radical mechanism. Moreover, MoO2/MoxC@NC@ZrO2 shows excellent stability, and the sulfur removal could remain over 96.5 % after thirteen cycles. This work not only opens up a new avenue for in situ integrating Mo-based heterojunctions, but also manifests a promising potential for practical ODS process.

Ultrasensitive and specific photoelectrochemical sensor for hydrogen peroxide detection based on pillar[5]arene-functionalized Au nanoparticles and MWNTs hybrid BiOBr heterojunction.

A photoelectrochemical sensor for target detection of hydrogen peroxide was designed based on a new heterojunction nanocomposite which was sulfhydryl-borate ester-modified A1/B1-type pillar[5]arene (BP5)-functionalized Au NPs and multi-walled carbon nanotubes hybridized with bismuth bromide oxide (Au@BP5/MWNTs-BiOBr). The specific sensor was based on the direct induction of oxidation by hydrogen peroxide of the borate ester group of pillar[5]arene. Additionally, the local surface plasmon resonance (LSPR) of Au NPs enhanced visible light capture, the host-guest complexation of BP5 with H2O2 enhanced photocurrent response, the layer-by-layer stacked nanoflower structure of BiOBr provided large specific surface area with more active sites, and the conductivity of MWNTs enhanced the charge separation efficiency and significantly improves the stability of PEC. Their synthesis effect significantly increased the photocurrent signal and further enhanced the detection result. Under the optimal conditions, the linear concentration range of H2O2 detected by the Au@BP5/MWNTs-BiOBr sensor was from 1 to 60pmol/L. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 0.333pmol/L and 1pmol/L, respectively, and the sensitivity was 6.471pmol/L. Importantly, the PEC sensor has good stability, reproducibility, and interference resistance and can be used for the detection of hydrogen peroxide in real cells.

CdIn2Se4@chitosan heterojunction nanocomposite with ultrahigh photocatalytic activity under sunlight driven photodegradation of organic pollutants

This research focused on synthesizing a CdIn2Se4@Ch nanocomposite by doping CdIn2Se4 into chitosan using a photolysis assisted ultrasonic process. The aim was to enhance the photodegradation efficiency of ofloxacin and 2,4-dichlorophenoxyacetic acid under sunlight. The synthesized CdIn2Se4@Ch nanocomposite was investigated via different techniques, including XRD, XPS, FTIR, TEM, DSC, TGA, UV–Vis and PL. The study also investigated the influence of various reaction parameters, including the effects of inorganic and organic ions. The synthesized nanocomposite demonstrated exceptional efficiency, achieving 86 % and 95 % removal rates, with corresponding rate constants of 0.025 and 0.047 min-1. This performance surpasses that of CdIn2Se4 by approximately 1.35 and 2.25 times, respectively. The values of COD were decreased to 78 and 86 % for ofloxacin and 2,4-dichlorophenoxyacetic, while the TOC values decreased to 71 and 84 %, respectively, from their premier values. The improvement in performance is associated with the introduction of CdIn2Se4 into chitosan, resulting in the self-integration of Cd into the catalyst. This creates a localized accumulation point for electrons, enhancing the efficiency of charge separation and further reducing the surface charge of chitosan. Experimental evidence suggests that superoxide and hydroxyl radicals play a significant role in the photodegradation of pollutants. Additionally, the nanocomposite exhibits excellent stability and can be reused up to five times, indicating remarkable stability and reusability of the developed photocatalyst.

α-Fe2O3/g-C3N4 nanocomposite with type II heterojunction for methylene blue photodegradation

Recently, the widespread use of industrial dyes, such as methylene blue, is raising concerns about organic pollutants. These compounds can persist in the environment, contaminating water sources and harming aquatic ecosystems. The aim of the current study is to develop a nano-composite by mechanically grinding graphitic carbon nitride g-C3N4 and hematite α-Fe2O3, which cloud potentially be used for degradation of Methylene bleu organic pollutant. The obtained heterojunction nanocomposite, named 1 % α-Fe2O3/g-C3N4 (Fe/gCN), was characterized using XRD, ATR-FTIR, and SEM-EDS analysis. The industrial methylene blue (MB) dye was used to assess the visible light photodegradation efficiency of the Fe/gCN nanocomposite. The findings revealed a notable improvement in the photocatalytic degradation performance of the Fe/gCN nanocomposite. Furthermore, the band gap of Fe/gCN nanocomposite was narrowed from 2,78 to 2,54 eV Comparing to gCN alone. Compared with pure α-Fe2O3 and gCN, the Fe/gCN nanoparticles showed enhanced visible-light-induced photocatalytic performance which degrade efficiently 99,64 % of MB dye. The optimal conditions were determined as: pH =10,3, photocatalyst mass of 0,6 g/l and contact time t = 120 min for the Fe/gCN composite. •OH and •O2− radicals were identified as the dominant active species responsible for MB degradation and played the most crucial roles, while h+ and e− radicals were less contributing in MB photocatalytic elimination. Kinetic studies indicated that the MB photocatalytic decomposition of by Fe/gCN followed a pseudo second-order (PSO) model. These findings underscore the great potential of Fe/gCN nanocomposite for the visible light-induced MB dye photodecomposition.

Room temperature gas sensors for NH3 detection based on SnO2 films and lamellar-structured Ti3C2Tx MXene heterojunction nanocomposites

Efficient and accurate detection of ammonia (NH3) by gas sensors at room temperature holds great practical value and significance in industrial production and environmental protection. In this work, we designed SnO2/Ti3C2Tx heterojunction nanocomposites via a facile RF magnetron sputtering technique. Benefitting from the surface porosity and few lamellar-structured of the composites, as well as the construction of heterojunctions between SnO2 and Ti3C2Tx, the SnO2/Ti3C2Tx sensor demonstrated a response of up to 13.35 % towards 50 ppm NH3 at room temperature, which was 3.5 times higher than the Ti3C2Tx-based sensor. Meanwhile, the response/recovery time was reduced to 24.9/86.5 s. In addition, the SnO2/Ti3C2Tx sensor exhibited good selectivity, repeatability, and long-term stability. This work should provide an effective strategy for the design of high-performance NH3 gas sensors at room temperature.

Ca-doping interfacial engineering and glycolysis enable rapid charge separation for efficient phototherapy of MRSA-infected wounds

Methicillin-resistant Staphylococcus aureus (MRSA) is the primary pathogenic agent responsible for epidermal wound infection and suppuration, seriously threatening the life and health of human beings. To address this fundamental challenge, we propose a heterojunction nanocomposite (Ca-CN/MnS) comprised of Ca-doped g-C3N4 and MnS for the therapy of MRSA-accompanied wounds. The Ca doping leads to a reduction in both the bandgap and the singlet state S1–triplet state T2 energy gap (ΔEST). The Ca doping also facilitates the two-photon excitation, thus remarkably promoting the separation and transfer of 808 nm near-infrared (NIR) light–triggered electron–hole pairs together with the built-in electric field. Thereby, the production of reactive oxygen species and heat are substantially augmented nearby the nanocomposite under 808 nm NIR light irradiation. Consequently, an impressive photocatalytic MRSA bactericidal efficiency of 99.98 ± 0.02 % is achieved following exposure to NIR light for 20 min. The introduction of biologically functional elements (Ca and Mn) can up-regulate proteins such as pyruvate kinase (PKM), L-lactate dehydrogenase (LDHA), and calcium/calmodulin-dependent protein kinase (CAMKII), trigger the glycolysis and calcium signaling pathway, promote cell proliferation, cellular metabolism, and angiogenesis, thereby expediting the wound-healing process. This heterojunction nanocomposite, with its precise charge-transfer pathway, represents a highly effective bactericidal and bioactive system for treating multidrug-resistant bacterial infections and accelerating tissue repair. Statement of significanceDue to the bacterial resistance, developing an antibiotic-free and highly effective bactericidal strategy to treat bacteria-infected wounds is critical. We have designed a heterojunction consisting of calcium doped g-C3N4 and MnS (Ca-CN/MnS) that can rapidly kill methicillin-resistant Staphylococcus aureus (MRSA) without damaging normal tissue through a synergistic effect of two-photon stimulated photothermal and photodynamic therapy. In addition, the release of trace amounts of biofunctional elements Mn and Ca triggers glycolysis and calcium signaling pathways that promote cellular metabolism and cell proliferation, contributing to tissue repair and wound healing.

Closing the loop: Waste carbon transformation into solar fuels via CdS/Bi2WO6 heterojunction

The advancement of semiconductor photocatalysis is acknowledged for its prowess as an eco-friendly, energy-efficient, and cost-effective method facilitating diverse organic transformations, including CO2 photoreduction. Despite its merits, there remains room for enhancing the selectivity and efficiency of these photocatalysts. In this study, we successfully synthesized heterojunction nanocomposites comprising CdS and Bi2WO6 semiconductors to drive the CO2-to-methanol conversion, achieving a maximum yield of 9450 μmol/g. Notably, CO (1048 μmol/g) and H2 (482 μmol/g) were also produced using water within a 16-h photocatalytic period, yielding an average production rate of ∼590 μmol/g-h. Triethylamine played a crucial role by providing electrons to the reaction system. The recovered photocatalyst exhibited consistent performance over five cycles of photoreduction experiments. Various spectroscopic and microscopic techniques were employed to analyze the optical, catalytic, and morphological properties of both the fresh and recovered photocatalysts. The introduced S-scheme heterojunction photocatalyst stands out for its efficient charge carrier separation, enhancing redox capacity, and holds promise as a source for novel strategies to improve the efficiency of CO2 photoreduction experiments.

Facile green synthesis of SnO2:Zn@g-C3N4 heterojunction nanocomposite using Murraya paniculata leaves extract for effective photocatalytic degradation of organic dye malachite green by sunlight illumination

In this work nanocomposite heterojunction of SnO2:Zn conjugated with g-C3N4 was successfully synthesized by a green synthesis method using Murraya paniculata leaves extract. Materials were characterized by XPS, FTIR, XRD, BET, HRTEM, FESEM, EDAX, and UV–visible spectrophotometer. XRD and HRTEM results revealed the formation of highly crystalline and small sized particles having mean grain size of 4.4 and 4.9 nm for SnO2:Zn and SnO2:Zn@g-C3N4, respectively and interplanar spacing of 0.333 nm. The 2-D sheeted structure of g-C3N4 acts as a translucent layer that captures and provide a considerable extent of self-agglomeration on the underlying sphere shaped SnO2:Zn NPs which results in excellent charge flow which eventually results in enhanced photocatalytic degradation performance of the synthesized heterojunction. The XPS analysis verifies the presence of Sn, Zn, O, C, and N in the synthesized heterojunction SnO2:Zn@g-C3N4. The UV–Visible and photoluminescence spectra helped to demonstrate the effective inhibition of excitons annihilation within the heterojunction nanocomposite. The heterojunction shows an excellent photodegradation efficiency of 93.84 % in the process of photodegradation of dye Malachite green (MG). Effect of pH, catalyst dose on photodegradation and the recyclability were also investigated. The kinetic plots were used to calculate the rate constant which shows the nature of a pseudo first order reaction with a rate constant of 0.299 min−1. Trap experiments were conducted to confirm the role of h+ and O2.− as active species.

Novel CuBi2O4-BiOCl/rGO heterostructure nanocomposite as high-performance visible light photocatalyst for the disintegration of persistent antimicrobials in aquatic environment

The article highlights the fabrication of a novel CuBi2O4-BiOCl/rGO heterojunction nanocomposite as a renewable visible light photocatalyst for the quick disintegration of a persistent fluoroquinolone-based antimicrobial drug, i.e., enrofloxacin (ENF) in aquatics. CuBi2O4-BiOCl (CBO-BOC) nanocomposites (NCs) of varying BOC stoichiometric ratios were synthesized, of which CBO-(30%) BOC NC (CB-30) revealed top photocatalytic traits, which was analogously dispersed onto reduced graphene oxide (rGO) nanosheets, to serve as the visible light photon responsive materials. The electron microscopic and spectroscopic techniques were deployed to understand the CB-30/rGO heterostructure's surface topography and structural morphology. The FE-SEM, HR-TEM and XPS analysis confirmed the dispersion of CBO nanospheres onto the BOC nanoflakes and further confirmed the successful imbuement of CB-30 NCs onto the rGO nanosheets. The CB-30/rGO photocatalyst revealed excellent porosity and surface area for the fast dissipation of pharmaceutical pollutants. The impact of various operating parameters, such as solution pH, drug concentration, CBO-BOC stoichiometry, CB-30/rGO dosage, photosensitizers/electron acceptors, light intensity and matrix tolerance limits, were augmented to enhance the photocatalytic efficiency of the proposed new-age photocatalyst. Under optimized conditions, complete drug mineralization was achieved in ≤0.33 h for complete mineralization of 30 ppm of ENF, using 0.075 g of photocatalyst. The time-dependent profiling of photoproducts/intermediates derived from the photocatalytic degradation of ENF was monitored by HR-MS analysis. The acute and chronic toxicity effects of ENF and its organic intermediate were predicted using the ECOSAR model for selected aquatic life forms. The photocatalyst exhibited reusability up to seven cycles, with excellent thermal/chemical stability, for pollutant decontamination from industrial effluents and environmental samples.

Temperature-dependent heterojunction ternary nanocomposite: Assessing photocatalytic and antibacterial applications

Heterojunction nanocomposites (ZnO:NiO:CuO) were synthesized via a hydrothermal method and annealed at three different temperatures (400 °C, 600 °C, and 800 °C). The structural, optical, and electrical properties were examined by employing XRD, SEM, UV–Vis, FTIR, and LCR meter techniques to investigate the effects of annealing. Increasing the annealing temperature resulted in the nanocomposites (NCPs) exhibiting enhanced crystallinity, purity, optical properties, and improved electrical and dielectric behavior. The calculated crystalline sizes (Debye-Scherrer method) of the NCPs were determined to be 21, 26 and 34 nm for annealing temperature 400 °C, 600 °C, and 800 °C, respectively. The calculated bandgaps of synthesized samples were found in the range of 2.92-2.55 eV. This temperature-dependent annealing process notably influenced particle size, morphology, band-gap characteristics, and photocatalytic efficiency. EDX analysis affirmed the sample purity, with elemental peaks of Zn, Cu, Ni, and O. These NCPs demonstrated exceptional photocatalytic activity against various dyes solutions (Methyl orange (MO), Methylene Blue (MB), and mixed solution of dyes) under sunlight and also showed good antibacterial properties assessed by the disc diffusion method. Notably, the nanocomposite annealed at 400 °C exhibited a particularly high degradation efficiency by degrading 96% MB and 91% MO in just 90 min under sunlight.