Formation Of Heterojunction Research Articles

High‐Performance Broad‐Spectrum UV Photodetectors with Uniform Response: Engineering β‐Ga2O3:Si/GaN:Si Heterojunctions via Thermal Oxidation for Optoelectronic Logic Gate and Multispectral Imaging

AbstractDeveloping high‐performance, broad‐spectrum ultraviolet photodetectors (PDs) with uniform response is crucial for optoelectronic applications like spectral analysis, optoelectronic logic gates, and multispectral imaging. This study constructs n‐n type β‐Ga2O3:Si/GaN:Si heterojunction PDs using thermal oxidation, combining the advantages of β‐Ga2O3:Si and GaN:Si for excellent broad‐spectrum response (UV‐A to UV‐C). A proposed channel model for GaN:Si oxidation includes hole formation, vortex structure development, channel formation, and grain growth, providing a basis for understanding β‐Ga2O3:Si/GaN:Si heterojunction formation. Uniform Si doping in the β‐Ga2O3 layer, achieved through thermal oxidation, reduces resistivity, enhances the collection of photogenerated carriers from the underlying GaN layer, and hence enhances broad‐spectrum response performance. The devices exhibit outstanding uniformity and sensitivity across the UV‐A to UV‐C range, with a peak responsivity of 2.44 × 104 A W−1 and a photocurrent‐to‐dark current ratio of 1.3 × 105. Applications include optoelectronic logic gates executing “OR gate” and “AND gate” logic operations with 254 and 365 nm UV light, and a single‐pixel multispectral imaging system producing high‐contrast, clear “CNU” images with 254, 295, and 365 nm UV light. This research advances the understanding of oxide heterojunction formation and offers a method for developing high‐performance, uniformly responsive broad‐spectrum UV photodetectors for optoelectronic applications.

A novel 0D/2D Z-scheme heterojunction Bi2Sn2O7/Bi4O7 for boosting tetracycline photodegradation: Insight from performance to mechanism

The slow migration and low separation efficiency of charge carriers inhibit the photocatalytic degradation of pollutants in water. Constructing heterojunction is an effective strategy to enhance photocatalytic performance. Herein, a novel Z-scheme Bi2Sn2O7/Bi4O7 (BOBSO) heterojunction was designed and synthesized for degrading typical antibiotics in water. The 0.2BOBSO heterojunction exhibits excellent photocatalytic performance, achieving a 97.97 % tetracycline degradation rate under visible light irradiation, significantly surpassing the individual materials Bi2Sn2O7 (75.93 %) and Bi4O7 (18.61 %). The composite photocatalyst shows excellent stability and strong adaptability to environmental factors. Compared to Bi2Sn2O7 and Bi4O7, 0.2BOBSO heterojunction possesses superior microstructure and photoelectrochemical properties confirmed by various characterizations. The electron transfer mechanism of Z-scheme heterojunction on the composite surface was proposed according to in-depth analyses using UV–vis, Mott-Schottky, and Electron Spin Resonance (ESR). The formation of Z-scheme heterojunction accelerates the migration of photogenerated charge carriers while maintaining the optimal redox ability of the materials. Furthermore, quenching experiments confirm that h+, O2−, and 1O2 are the main active species in the reaction system, with TC degraded via both radical and non-radical pathways. This study provides new insights into the design and construction of 0D/2D Z-scheme heterojunction photocatalysts.

Ultrasound-induced rapid electron movement on ZnO/MoS2 heterojunction for high performance tumor therapy

Conventional methods for treating tumors not only have limited therapeutic efficacy but also cause harm to patients, so there is an urgent need to develop a new therapeutic approach. Sonodynamic therapy (SDT), with its strong tissue penetration and few side effects, is considered to be an effective means of treating tumors. However, the reactive oxygen species (ROS) produced by a single piezoelectric material is often limited and does not achieve a complete tumor cure. In this paper, a ZnO/MoS2 heterojunction is synthesized by hydrothermal immobilization of MoS2 on ZnO to enhance the effect of SDT. Meanwhile, due to the electron exchange between ZnO and MoS2, a layer of ZnS is formed between ZnO and MoS2. Under ultrasound (US) irradiation, the ZnO/MoS2 heterojunction can effectively eliminate breast cancer cells within 10 min. This is mainly due to the better piezoelectric catalytic ability of ZnO/MoS2 than pure ZnO. Electrochemical and Uv–vis tests show that the formation of heterojunction accelerates the separation of electrons and holes and inhibits carrier complexation, so that more oxygen substrates will react with electron-hole pairs to generate ROS. This work provides a novel idea to take the treatment of tumors by enhancing piezoelectric catalysis through the construction of heterojunction interfaces.

High-efficiency PMS activation by difunctional Co-Fe PBA/g-C3N4 S-scheme heterojunction for oxytetracycline degradation: Performance evaluation and mechanism insight

The utilization of sulfate radical-based advanced oxidation processes (SR-AOPs) has captivated the academic community due to their minimal energy requirements and superior efficacy in peroxomonosulfate (PMS) activation for pollutant decomposition. Notwithstanding these advantages, engineering an effective and economical catalyst for PMS activation presents a considerable hurdle. In the present study, a metal-organic framework of CoFe PBA is ingeniously anchored onto g-C3N4 nanosheets, resulting in the formation of an innovative CoFe PBA/g-C3N4 S-scheme heterojunction that demonstrates remarkable efficiency in PMS activation. Intriguingly, the catalytic efficiency of CoFe PBA/g-C3N4 surpasses that of g-C3N4 and CoFe PBA by 7-fold and 2.33-fold, respectively. The heightened activity of CoFe PBA/g-C3N4 heterojunction is attributed to the enhanced charge transfer efficiency, a consequence of the successful heterojunction formation. Concurrently, the ability of photoexcited electrons to reduce Co3+/Fe3+ to Co2+/Fe2+ bolsters PMS activation. Significantly, this heterojunction retains unparalleled stability in degrading oxytetracycline without discernible performance attenuation, heralding its commendable prospects in real-world applications. Besides, mechanism exploration indicates that SO4−, h+, and electron transfer contribute to oxytetracycline degradation in the CoFe PBA/g-C3N4 system. This investigation serves as a beacon for the strategic development of highly active and stable catalysts for PMS activation, aiming at environmental decontamination.

Water process/treatment by a S-scheme Fe2O3/TiO2 heterojunction photocatalyst for excellent antibiotic degradation/CO2 reduction/H2 production; process optimization and mechanistic insights

A facile synthesis approach was employed to fabricate a binary Fe2O3/TiO2 nanocomposite (FeTi4-400) for enhanced photocatalytic hydrogen (H2) production, cephalexin degradation and CO2 reduction under visible light irradiation. Compared to pristine TiO2, FeTi4-400 exhibited improved visible light absorption and promoted charge carrier separation, leading to increased H2 production rate and CO2 conversion into CH4 and CO. This improvement can be attributed to the formation of an S-scheme heterojunction, along with the desirable properties of FeTi4-400, including visible light activity, high surface area, and strong CO2 adsorption. The photocatalyst achieved a maximum H2 production rate of 649 μmol/g·h−1, exceeding that of pure TiO2. Similarly, the highest CO production rate of 16.44 μmol/g·h−1 was attained with FeTi4-400. Furthermore, FeTi4-400 achieved excellent cephalexin degradation (96 %) under optimal conditions, with a degradation rate constant of 0.01 min−1. A plausible cephalexin degradation pathway over FeTi4-400 is proposed. Transient photocurrent measurements and EIS analysis corroborated a significant enhancement in photocatalytic activity for FeTi4-400, attributed to the efficient separation of photogenerated electron-hole pairs. Stability studies demonstrated consistent cephalexin degradation by FeTi4-400 over five consecutive cycles without noticeable photocatalyst deactivation. This work presents a novel strategy for fabricating low-cost, efficient, and readily synthesized nanomaterials for applications in solar energy conversion and environmental remediation.

Layered Ti3C2Tx MXene heterostructured with V2O5 nanoparticles for enhanced room temperature ammonia sensing

To enhance ammonia sensing at room temperature (25°C), Two-dimensional transition metal carbonyl nitride (Ti3C2Tx MXene) modified by vanadium pentoxide nanoparticle (V2O5) is synthesized by hydrothermal method. The effects of weight ratio on the microstructure and ammonia sensing performance at room temperature are studied. The results indicate that when the weight percentage of V2O5 is 25 %, V2O5 nanoparticles with an average size of 90.33 nm are produced on the surface and between the layers of the two-dimensional MXene. The prepared MXene/V2O5 composites sensor has a good response (12.12) to 10 ppm NH3. The enhanced sensing performance can be attributed to the modification of V2O5 nanoparticles as well as the catalytic effect and the formation of heterojunction. The doped V2O5 nanoparticles open up the unstratified portion of MXene and catalyze the chemisorption of oxygen and oxidation of NH3. The difference in Fermi level between two-dimensional MXene and V2O5 drives the charge transfer at the heterojunction interface, enriching the electrons on the surface of V2O5, thus improving the sensitivity. Density functional theory suggests that the composite adsorption system is more stable and has lower NH3 adsorption energy. This work provides a feasible route to develop high-performance gas sensors with MXene-based composites.

In Situ Generation of Microwire Heterojunctions with Flexible Optical Waveguide and Hydration-Mediated Photochromism.

Flexible heterojunctions based on molecular systems are in high demand for applications in photonics, electronics, and smart materials, but fabrication challenges have hindered progress. Herein, we present an in situ approach to creating optical heterojunctions using hydration-mediated flexible molecular crystals. These hydrated multi-component molecular solids display strong blue emitting optical waveguides with minimal optical loss (0.005 dB/μm) and excellent flexibility (elastic modulus: 3.87 GPa). The water-mediated process enables the molecular microwires with tunable elastic and plastic deformation, as well as reversible uptake and release of lattice water, facilitating the formation of flexible heterojunctions. Spectral analysis and theoretical modeling reveal that these microwires exhibit both photochromism and color-tunable dual emission (fluorescence and phosphorescence), expanding their utility in photonic information encoding. Therefore, this work introduces a hydration-mediated molecular engineering strategy for fabricating crystalline heterojunctions with on-demand processability and controllable emission sequences, enabling optical signal manipulation at the micro/nanoscale.

Boosting the photocatalytic benzylamine oxidation and Rhodamine B degradation using Z-scheme heterojunction of NiFe2O4/rGO/Bi2WO6

The construction of heterojunction photocatalysts with powerful interfacial connections is critical for the actual utilization of photocatalytic technology. In this paper, the heterojunction photocatalyst NiFe2O4/rGO/Bi2WO6 (NFO/rGO/BWO) was prepared by in-situ hydrothermal method. Due to its excellent conductivity, rGO promoted the separation of photogenerated carriers, which was beneficial to the formation of Z-scheme heterojunction between NFO and BWO, and the absorption of visible light was improved by the involvement of rGO and NFO. Among a series of synthesized photocatalysts, 3 % NFO/rGO/BWO had the best photocatalytic activity in the photocatalytic oxidative coupling of benzylamine (BA). After 180 min of illumination, high conversion of 96 % for BA was achieved, which was 2.6 times higher than that of BWO. When it was applied to the degradation of Rhodamine B (RhB), complete degradation could be achieved, and the degradation rate was 5.67 times than that of BWO. The important roles of h+ and •O2– in the reaction were confirmed by electron spin resonance (ESR) analysis and radical capture experiments. The density functional theory (DFT) calculation and bandgap structure of the catalysts verified the existence of Z-scheme heterojunction. Potential reaction pathways for photocatalytic BA coupling and RhB degradation were proposed, respectively.

Optimization of Al2O3 shell thickness on SnO2 nanowires for realization of sensitive and selective H2 sensing

Detection of highly explosive H2 gas is a critical safety issue. Herein, using a vapor-liquid-solid growth mechanism, SnO2 nanowires (NWs) were prepared, after which Al2O3 shells (1.9, 3.3, 4.5, and 6.1 nm) were deposited on synthesized SnO2 NWs by atomic layer deposition. Based on characterization studies, C-S NW structures with a crystalline SnO2 core and amorphous Al2O3 shell were successfully formed. Based on H2 gas sensing measurement, SnO2-Al2O3 (4.5 nm) C-S NWs exhibited a high response of 152.54 to H2 (10 ppm) at 350°C. Furthermore, they showed excellent selectivity, where response to H2 gas (10 ppm) was more than 33 times higher than that to NO2 gas (10 ppm). Additionally, they displayed excellent repeatability as well as long-term stability in detection of low-concentration H2 gas. The improved H2 sensing capability was related to the high base resistance, the formation of the SnO2-Al2O3 heterojunction, the optimization of the Al2O3 shell thickness on SnO2 NWs, and the partial reduction of SnO2 and Al2O3 in an H2 gas atmosphere. This study sheds light on the development of H2 sensors based on present material.

Photoelectrochemical immunosensor for chloramphenicol detection based on cation exchange reaction-mediacted photocurrent enhancement of ZnIn2S4/TiO2/Ti3C2 MXene coupled with controlled-release strategy.

Aphotocurrent enhancing photoelectrochemical (PEC) immunosensor was developedfor chloramphenicol (CAP) detection based on cation exchange reaction. The efficient split-type PEC immunosensor combined with controlled-release strategy was established using the ZnIn2S4/TiO2/Ti3C2 MXene (ZIS/T/M) composite as the photoactive material and CuO as the signal response probe. In the presence of target CAP, CuO-labeled CAP antibody (CuO-mAb) was introduced onto the microplate via a competitive-type immunoassay. Under acidic conditions, a large amount of Cu2+ released from CuO-mAb, which triggered a cation exchange reaction with the Zn2+ in ZIS/T/M-modified photoelectrode to generate CuxS, resulting in enhancingthe photocurrent. As a result, the quantitative detection of CAP was achieved by detecting the photocurrent change. Under optimized conditions, the linear range of the sensor was 1pg/mL to 50ng/mL, and the detection limit was 0.24pg/mL. The excellent PEC behavior of ZIS/T/M composite could be attributed to the fact that heterojunction formation improved the migration and separation of thephotocarrier. Additionally, by virtue of the photocurrent-enhancing strategy via cation exchange reaction and the controlled releasing signal amplification method of ion, the PEC immunosensor has high sensitivity and satisfactory accuracy, offering great potential applications in the determinationof CAP.

Efficiently Designed Three-Dimensional Architecture of CoMn2O4 Decorated V2CTx MXene for Asymmetric Supercapacitors.

The structure, morphology, stoichiometry, and chemical characterization of the V2CTx MXene, CoMn2O4, and V2C@CoMn2O4 nanocomposite, prepared by using a soft template method, have been studied. The electron microscopy studies reveal that the V2C@CoMn2O4 composite incorporates mesoporous spheres of CoMn2O4 within the 2D layered structure of MXene. The specific capacitance of the composite electrode is ∼570 F g-1 at 1 A g-1, which is significantly higher than that of the sum of the individual components. It also exhibits great rate capability and a Coulombic efficiency of ∼96.5% over 10000 cycles. An asymmetric supercapacitor prototype created with V2C@CoMn2O4//activated carbon outperformed other reported ASCs in terms of achieving a high energy density of 62 Wh kg-1 at a power density of 440 W kg-1. The improved response of V2C@CoMn2O4 and ASC is attributed to the enhanced active area available for charge transfer and the synergistic interaction between CoMn2O4 spherical particles and nanolayered MXene. Supporting density functional theory (DFT) calculations are performed to understand the impact of composite heterojunction formation on its detailed electronic structure. Our atomistic simulations reveal that by incorporating CoMn2O4 in V2C, the density of electronic states at the Fermi level increases, boosting the charge transfer characteristics. These modifications in turn enhance the charge storage capabilities of heterojunction. Finally, the merits of the V2C@CoMn2O4 composite electrode are discussed by comparing it with those of other existing high-performance MXene-based composite electrodes.

Boosting piezocatalytic activity for hydrogen bonding self-assembled Ti3C2/BaTiO3 heterojunction via accumulated piezoelectric effect

Constructing heterojunctions has been proved to effectively improve the carrier transfer capability for enhanced catalytic activity. Herein, Ti3C2/BaTiO3 heterojunctions were fabricated through self-assembly driven by hydrogen bonding between piezoelectric barium titanate (BaTiO3) stabilized by oleic acid molecules and titanium carbide (Ti3C2) with surficial functional groups under continuous ultrasonic vibration. Owing to the formation of heterojunction, the separation of free charges can be promoted by the conductive Ti3C2. Additionally, the recombination of electrons and holes pairs in BaTiO3 can be hindered by built-in piezoelectric field. Hence, the piezocatalytic activity of Ti3C2/BaTiO3 was significantly enhanced by the accumulated piezoelectric effect, maintaining stability during the piezocatalytic degradation of bisphenol A and achieving rate constants that were 22.2 and 3.2 times higher than those of Ti3C2 and BaTiO3, respectively. This work thus presents a novel strategy for designing high-activity heterojunction piezocatalysts through hydrogen bonding self-assembly.

Improving Photocatalytic Hydrogen Production with Sol–Gel Prepared NiTiO₃/TiO₂ Composite

This study presents a comprehensive investigation into the synthesis, characterization, and photocatalytic performance of NiTiO3/TiO2 nanocomposites for solar hydrogen production. Through a carefully optimized sol–gel method, we synthesized a heterojunction photocatalyst comprising 99.2% NiTiO3 and 0.8% anatase TiO2. Extensive characterization using XRD, Raman spectroscopy, FTIR, UV–visible spectroscopy, photoluminescence spectroscopy, and TEM revealed the formation of an intimate heterojunction between rhombohedral NiTiO3 and anatase TiO2. The nanocomposite demonstrated remarkable improvements in optical and electronic properties, including enhanced UV–visible light absorption and an 85% reduction in charge carrier recombination compared to pristine NiTiO3. Crystallite size analysis showed a reduction from 53.46 nm to 46.35 nm upon TiO2 incorporation, leading to increased surface area and active sites. High-resolution TEM confirmed the formation of well-defined interfaces between NiTiO3 and TiO2, with lattice fringes of 0.349 nm and 0.249 nm corresponding to their respective crystallographic planes. Under UV irradiation, the NiTiO3/TiO2 nanocomposite exhibited superior photocatalytic performance, achieving a hydrogen evolution rate of 9.74 μmol min−1, representing a 17.1% improvement over pristine NiTiO3. This enhancement is attributed to the synergistic effects of improved light absorption, reduced charge recombination, and efficient charge separation at the heterojunction interface. Our findings demonstrate the potential of NiTiO3/TiO2 nanocomposites as efficient photocatalysts for solar hydrogen production and contribute to the development of advanced materials for renewable energy applications.

Boosted photoinduced charge separation in FeNi2S4@Cd0.9Zn0.1S Step-scheme heterojunction for photothermal assisted photocatalytic water splitting into hydrogen

Rational design of photocatalysts with photothermal effect to maximize light utilization is pivotal in achieving superior photocatalytic efficiency. In this work, by coating Cd0.9Zn0.1S (CZS) nanorods on hollow FeNi2S4 (FNS) microspheres with photothermal effect, a novel FeNi2S4@Cd0.9Zn0.1S (FNS@CZS) Step-scheme (S-scheme) heterojunction photocatalyst was constructed for efficient photothermal-assisted hydrogen (H2) evolution via simultaneously employing light and thermal energy. The hollow structure of FNS microsphere not only provides abundant reactive sites but also serves as a supportive substrate for CZS nanorods, effectively inhibiting their agglomeration. And the unique hollow structure of FNS allows for multiple reflections and refractions of visible light, enhancing the local temperature of the photocatalyst. This effectively minimizes thermal losses within the composite system, thereby enhancing the efficiency of light energy utilization. Furthermore, the formation of the S-scheme heterojunction facilitates the efficient separation of photogenerated charge carriers and enhances the activity of redox reactions, thereby boosting the overall photocatalytic activity. Experimental results reveal that the H2 production rate of the FNS@CZS heterojunction reaches 12.9 mmol·g−1·h−1, which is 25.1 times higher than that of pristine CZS. By controlling the experimental temperature, the impact of the photothermal effect on the photocatalytic H2 production rate has been clarified. According to relevant evidence from infrared thermography and DFT calculations, comprehensive analyses and discussions were conducted on the photothermal effect and S-scheme charge transfer mechanisms. This study offers guidance on designing photothermal-enhanced photocatalysts to achieve satisfactory H2 production activity.

Plasma-assisted construction of waterfall-type IEF in N-TiO2/WO3 S-scheme heterojunction for efficient visible-light-driven degradation of Cl-VOCs

Constructing S-scheme heterojunctions with a robust internal electric field (IEF) to enhance the photocatalytic degradation of chlorinated volatile organic compounds (Cl-VOCs) presents a significant challenge. Herein, an innovative S-scheme heterojunction of N-doped titanium dioxide (TiO2) and tungsten trioxide (WO3) with abundant oxygen vacancies (OVs) was synthesized and manipulated for the first time via an eco-friendly two-step plasma. The charge transfer pathway between TiO2 and WO3 was analyzed using UV–Vis DRS, XPS, UPS, and EPR measurements, confirming the successful formation of the S-scheme heterojunction. Interestingly, two novel types of IEF, stream-type and waterfall-type were proposed for the first time to distinguish the IEF strength before and after regulation. Under visible light, 5NTW, with the optimal ratio of 4.66 at% nitrogen and 5 wt% WO3, achieved the highest degradation efficiency and carbon dioxide mineralization rate, 95.4% and 94.1% for chlorobenzene, respectively. The performance enhancement was attributed to the fact that N-doping modifies the electronic structure and work function of TiO2, enhancing the Fermi level difference (ΔEf) with WO3. Meanwhile, the plasma treatment roughened the surface topography of the catalyst and increased the content of OVs, which serve as charge traps and bolster active sites. These synergies led to a transformation from a stream-type IEF of TW to a waterfall-type IEF of 5NTW. KPFM, zeta potential tests, and DFT calculations confirmed that the IEF strength and the number of electron transfers in the waterfall-type IEF are 3.17 and 2.04 times greater, respectively, than those in the stream-type IEF. This strategy transcends the limitations of previous work, offering a novel perspective on the integrated optimization of photocatalysts for superior performance and also further broadens the application prospects of nonthermal plasma technology.

Integration of Cu2O-NiTiO3 as an efficient p-n heterojunction visible light photocatalytic system for the simultaneous removal of Cr (VI) and Alizarine Cyanine Green dye

Cu2O loaded NiTiO3 based p-n heterojunction photocatalysts of various proportions have been synthesized by liquid phase reduction process resulting in NiTiO3 nanoparticles dispersed on the surface of Cu2O. Formation of both oxide phases is confirmed from the XRD, HR-SEM and XPS analysis. Heterojunction formation is confirmed by the intimate contact between NiTiO3 and Cu2O as evidenced by HR-TEM. UV-Vis spectra exhibit a red shift indicating the extended visible light absorption. XPS shows the presence of oxidation states of Ni2+, Ti4+, Cu+, Cu2+ and O2-. Heterojunction materials showed enhanced activity for the simultaneous photocatalytic reduction of Cr (VI) and degradation of Alizarine Cyanine Green dye under visible light irradiation. 1:2 ratio of Cu2O and NiTiO3 heterojunction (1C:2N) material exhibits 100% dye degradation in 90 minutes and Cr (VI) reduction in 180 minutes. Higher activity of Cu2O-NiTiO3 p-n heterojunction is ascribed to the effective charge separation and extended visible light absorption

Tin oxide nanoparticles anchored on ordered mesoporous carbon for efficient acetone sensing

Rationally designed combinations of semiconductor metal oxides (SMO) and carbon materials can lead to the development of sensing materials with excellent gas performance. Herein, SnO2 nanoparticles (NPs) decorated on ordered mesoporous carbon (CMK-3) nanorods were synthetized by solvothermal and high-temperature calcination methods. Various characterization and gas sensing tests indicated that the resulting one-dimensional (1D) self-assembled SnO2@CMK-3 composite had a large specific surface area (88.02 m2/g) and excellent gas sensing performance. Specifically, at optimal working temperature, the as-prepared SnO2@CMK-3 sensor had a high response (122.1), low limit of detection, good linear fitting (R2 = 0.9892), rapid response/recovery time (5/27 s) towards 50 ppm acetone. Meanwhile, by detecting six gases, including acetone, ammonia, formaldehyde, xylene, triethylamine, and ethanol, it was found that the SnO2@CMK-3 sensor showed good selectivity to acetone. The unique nanostructure, large specific surface area, high oxygen vacancy content, and the formation of heterojunctions accounted for the good performance to acetone. These results highlighted the potential application of the SnO2@CMK-3 composite for the detection of acetone gas and presented a promising approach to prepare SMO@carbon composites for VOCs detection.

Harnessing natural light: Novel nanoheterojunction photocatalyst NaGdF4:Yb,Tm@TiO2/Cu2(OH)2CO3 for actual wastewater remediation

This study introduces NaGdF4:Yb,Tm@TiO2/Cu2(OH)2CO3 (UTCu), an innovative nanophotocatalyst designed to address global energy crises and water contamination issues. Our developed photocatalyst, NaGdF4:Yb,Tm@TiO2/0.5mol%Cu2(OH)2CO3 (UTCu0.5), demonstrated exceptional efficiency, degrading 96.3% of malachite green (MG) within 2 h under Xenon lamp irradiation. The photocatalytic degradation rate of UTCu0.5 surpassed those of UT, Cu2(OH)2CO3, and P25 (Commercial TiO2) by 3.3, 9, and 2.8 times, respectively. The process effectively mineralized MG into less harmful compounds, marking its potential for eco-friendly wastewater treatment. Furthermore, UTCu0.5 exhibited robust degradation capabilities across various organic dyes and maintained its efficacy in mixed dye systems. Detailed mechanistic analysis revealed that the ·OH and ·O2− radicals play pivotal roles in the degradation process, facilitated by the formation of heterojunctions that enhance carrier separation and photocatalytic performance. Theoretical studies supported the significance of S-scheme heterojunctions in boosting the photocatalytic activity of UTCu0.5. Additionally, the catalyst was effective in degrading organic pollutants in different water matrices under both Xenon lamp irradiation and direct sunlight. Remarkably, it achieved a 77.4% removal rate of NH4⁺-N in real municipal wastewater under natural sunlight, with a selective conversion rate of 95.3% to N2, underscoring its practical applicability in environmental remediation. This research not only progresses photocatalysis technology but also provides vital insights for enhancing natural condition wastewater treatment strategies.

Development and Performance of ZnO/MoS2 Gas Sensors for NO2 Monitoring and Protection in Library Environments

The presence of harmful oxidizing gases accelerates the oxidation of cellulose fibers in paper, resulting in reduced strength and fading ink. Therefore, the development of highly sensitive NO2 gas sensors for monitoring and protecting books holds significant practical value. In this manuscript, ZnO/MoS2 composites were synthesized using sodium molybdate and thiourea as raw materials through a hydrothermal method. The morphology and microstructure were characterized by X-ray diffraction analysis (XRD), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ZnO/MoS2 composite exhibited a flower-like structure, with ZnO nanoparticles uniformly attached to the surface of MoS2, demonstrating advantages such as high specific surface area and good uniformity. The gas sensitivity of the ZnO/MoS2 nanocomposites reached its peak at 260 °C, with a sensitivity value around 3.5, which represents an improvement compared to pure ZnO, while also enhancing sensitivity. The resistance of the ZnO/MoS2 gas sensor remained relatively stable in air, exhibiting short response times during transitions between air and NO2 environments while consistently returning to a stable state. In addition to increasing adsorption capacity and improving light utilization efficiency, the formation of hetero-junctions at the ZnO-MoS2 interface creates an internal electric field that effectively promotes the rapid separation of photo-generated charge carriers within ZnO, thereby extending carrier lifetime.

Interface-Engineered CuxO@Bi2MoO6 Heterojunctions to Inhibit Piezoelectric Screening Effect and Promote Double-Nanozyme Catalysis for Antibacterial Treatment.

Sonodynamic therapy is confronted with the low acoustic efficiency of sonosensitizers, and nanozymes are accompanied by intrinsic low catalytic activity. Herein, to increase the piezopotential of N-type piezoelectric semiconductors, the P-N heterojunction is designed to inhibit the piezoelectric screening effect (PSE) and increase electron utilization efficiency to enhance nanozyme activity. P-type CuxO nanoparticles are in situ grown on N-type piezoelectric Bi2MoO6 (BMO) nanoflakes (NFs) to construct heterostructured CuxO@BMO by interface engineering. CuxO deposition leads to lattice distortion of BMO NFs to improve piezoelectric response, and the strong interface electric field (IEF) suppresses PSE and increases piezopotential. The nonlocal piezopotential, local IEF, and glutathione (GSH) inoculation enhances electron-hole separation and increases peroxidase (POD)-like activity of BMO and GSH oxidase (GSHOx)-like activity of CuxO with high selectivity. The heterojunction formation causes the transfer and rearrangement of interface electrons, and the increased piezopotential accelerates electron transfer at interfaces with bacteria, thus increasing the production of reactive oxidative species and interfering with adenosine triphosphate synthesis. The heterostructured nanozymes produce abundant intracellular ·OH and achieve 4log magnitude reductions in viable bacteria and effective biofilm dispersion. This study elucidates integral mechanisms of nanozyme and acoustic catalysis and opens up a new way to synergize high piezopotential and nanozyme-catalyzed therapy.