Search Results (50)

In this study, the BPTCD/g-C₃N₄ heterojunction photocatalyst was successfully prepared by the hydrothermal method. BPTCD (3,3′,4,4′-benzophenone tetracarboxylic dianhydride) is immobilised on the surface of g-C₃N₄ by non-covalent π-π stacking. The BPTCD/g-C₃N₄ heterojunction photocatalyst is an all-organic photocatalyst with significantly improved photocatalytic performance compared with g-C₃N₄. BPTCD/g-C₃N₄-60% was able to effectively degrade MO solution (10 mg/L) to 99.9% and 82.8% in 60 min under full spectrum and visible light. The TOC measurement results indicate that MO can ultimately be decomposed into H₂O and CO₂ through photocatalytic action. The photodegradation of methyl orange by BPTCD/g-C₃N₄ composite materials under sunlight is mainly attributed to the successful construction of the heterojunction structure and its excellent π-π stacking effect. Superoxide radicals (^•O₂⁻) were found to be the main active species, while ^•OH and h⁺ played a secondary role. The synthesised BPTCD/g-C₃N₄ also showed excellent stability in the activity of photodegradation of MO in wastewater, with the performance remaining above 90% after three cycles. The mechanism of the photocatalytic removal of MO dyes was also investigated by the trap agent experiments. Additionally, BPTCD/g-C₃N₄-60% demonstrated exceptional photodegradation performance in the degradation of methylene blue (MB). BPTCD/g-C₃N₄ heterojunctions have great potential to degrade organic pollutants in wastewater under solar irradiation conditions. Full article

A three-dimensional Bi-enriched Bi₂O₃/Bi₂MoO₆ Z-scheme heterojunction photocatalyst was successfully synthesized via a facile one-step hydrothermal method for efficient phenol degradation under visible light. Structural and morphological characterizations (SEM, TEM, and XRD) confirmed the formation of a nanoflower-like architecture with a high specific surface area of 81.27 m²/g. Optical and electrochemical analyses revealed efficient charge separation and extended visible-light response. Under visible-light irradiation (λ > 420 nm), this heterojunction (Bi₂O₃:Bi₂MoO₆ = 3:7) demonstrated exceptional performance, degrading 97.06% of phenol (30 mg/L) within 60 min. XPS analysis confirmed the Z-scheme charge transfer mechanism: Photogenerated electrons in the conduction band of Bi₂O₃ (−0.59 eV) facilitated the generation of ·O₂⁻ radicals, while holes in the valence band of Bi₂MoO₆ (2.44 eV) predominantly produced ·OH radicals. This synergistic effect resulted in highly efficient mineralization and degradation of phenol. Full article

In this work, a novel dual Z-scheme CdS/Ag₂MoO₄/β-Bi₂O₃ (CAB) composite heterojunction was synthesized, with the ultrafine CdS nanoparticles decorating two different-sized particles. In the beginning, the synergistic effect between BO and AMO makes the 10% Ag₂MoO₄/β-Bi₂O₃ (10AB) photocatalyst exhibit an optimal degradation efficiency of 87.1% for methylene blue (MB) of 10 mg·L⁻¹ within 60 min; furthermore, its photocatalytic activity was enhanced by incorporating CdS nanoparticles on the surface of the AB heterojunction. The results showed that the 25% CdS/10% AMO/BO (25C10AB) composite achieved a maximum MB degradation efficiency of 99%. Optical and photoluminescence measurements showed that the dual Z-scheme CAB heterojunction has high crystallinity and efficient charge carrier migration and separation, which makes the samples more efficient for removing pollutants. Theoretical studies (DFT/FEM calculations) were performed to better understand the migration direction of e⁻ and h⁺ in the photocatalytic degradation mechanism. This work provides a feasible approach to obtaining an efficient heterojunction composite photodegradation catalyst. Full article

Utilizing two or more semiconductor materials with distinct geometric and electronic energy arrangements at the nanoscale to construct heterostructures is an important means for developing high-performance catalysts for photocatalytic hydrogen evolution. In this study, ZnIn₂S₄ serves as the primary catalyst carrier, while Mo-W₁₈O₄₉ functions as the cocatalyst supported on the surface of ZnIn₂S₄. A series of ZnIn₂S₄/Mo-W₁₈O₄₉ heterojunction composite materials were synthesized through a straightforward hydrothermal method. The ZnIn₂S₄/Mo-W₁₈O₄₉ photocatalyst demonstrates exceptional photocatalytic hydrogen evolution activity. Notably, with a Mo-W₁₈O₄₉ loading of 10%, the photocatalyst achieves optimal hydrogen evolution, yielding 2592.8 μmol g⁻¹, which is 31 times greater than that of pure ZnIn₂S₄. Further characterized results of the samples showed that loading Mo-W₁₈O₄₉ with an appropriate mass ratio on ZnIn₂S₄ can increase the electron transfer rate, which facilitates reducing the recombination probability of photo-generated electrons and holes, thus improving hydrogen evolution efficiency. Full article

Semiconductors have emerged as promising candidates for surface-enhanced Raman scattering (SERS) applications due to their inexpensiveness and good chemical stability. Nevertheless, their low enhancement ability compared to noble metals makes it desirable to explore strategies for improving SERS performance. Since charge transfer (CT) between semiconductors and analytes plays a crucial role on the chemical enhancement mechanism of SERS, heterojunction engineering, a powerful method to boost optoelectronic performance via tailoring interfacial charge transfer, provides a promising approach. Here, we prepared defect-rich WO_3-x/TiO₂ nanocomposites via a facile solvothermal method to achieve dual-functional enhancement in SERS and photocatalytic activity. Due to suppressed recombination of charge carriers in WO_3-x/TiO₂ heterojunction with type II band alignment, more photogenerated carriers are available for CT, consequently increasing molecular polarizability. The SERS intensity of WO_3-x/TiO₂ is at least three times that of its component semiconductors, with a detection limit of 10⁻¹⁰ M for methyl orange (MO). Meanwhile, the suppressed recombination of charge carriers also results in higher degradation efficiency of WO_3-x/TiO₂ heterojunction (93%) than WO_3-x (47%) and TiO₂ (54%) under visible-light irradiation for 120 min. This work provides insightful information on the development of dual-functional semiconductor systems through band structure engineering for ultrasensitive sensing and efficient remediation of environmental pollutants. Full article

This study successfully prepared MIL-101(Fe)@MoS₂ composite photocatalysts via hydrothermal methods to address the efficient removal of refractory organic dyes in dye wastewater. Characterization using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) confirmed that molybdenum disulfide (MoS₂) was uniformly loaded onto the surface of MIL-101(Fe), forming a heterojunction that significantly enhanced light absorption capacity and charge separation efficiency. In a visible-light-driven photo-Fenton system, this material exhibited excellent degradation performance for Congo red (CR). At an initial CR concentration of 50 mg/L, a catalyst dosage of 0.2 g/L, 4 mL of added H₂O₂, and pH 7, CR was completely degraded within 30 min, with the total organic carbon (TOC) removal reaching 72.5%. The material maintained high degradation efficiency (>90%) across a pH range of 3–9, overcoming the traditional Fenton system’s dependency on acidic media. Radical-trapping experiments indicated that superoxide radicals (·O₂⁻) and photogenerated holes (·h⁺) were the primary active species responsible for degradation, revealing a synergistic catalytic mechanism at the heterojunction interface. Recyclability tests showed that the material retained 90.8% degradation efficiency after five cycles, and an X-ray photoelectron spectroscopy (XPS) analysis demonstrated the stable binding of Fe and Mo, preventing secondary pollution. This study provides a scientific basis for developing efficient, stable, and wide-pH adaptable photo-Fenton catalytic systems, contributing significantly to the advancement of green water treatment technologies. Full article

This study proposed a novel perovskite/silicon heterojunction (SHJ) tandem device structure without an interlayer, represented as ITO/NiO/perovskite/SnO₂/MoO_X/i-a-Si:H/n-c-Si/i-a-Si:H/n-a-Si:H/Ag, which was investigated by Silvaco TCAD software. The recombination layer in this structure comprises the carrier transport layers of SnO₂ and MoO_X, where MoO_X serves dual functions, acting as the emitter for the SHJ bottom cell and as part of the recombination layer in the tandem cell. First, the effects of different recombination layers are analyzed, and the SnO₂/MoO_X layer demonstrates the best performance. Then, we systematically investigated the impact of the carrier concentration, interface defect density, thicknesses of the SnO₂/MoO_X layer, different hole transport layers (HTLs) for the top cell, absorption layer thicknesses, and perovskite defect density on device performance. The optimal carrier concentration in the recombination layer should exceed 5 × 10¹⁹ cm⁻³, the interface defect density should be below 1 × 10¹⁶ cm⁻², and the thicknesses of SnO₂/MoO_X should be kept at 20 nm/20 nm. CuSCN has been found to be the optimal HTL for the top cell. When the silicon absorption layer is 200 μm, the perovskite layer thickness is 470 nm, and the defect density of the perovskite layer is 10¹¹ cm⁻³, the planar structure can achieve the best performance of 32.56%. Finally, we studied the effect of surface texturing on the SHJ bottom cell, achieving a power conversion efficiency of 35.31% for the tandem cell. Our simulation results suggest that the simplified perovskite/SHJ tandem solar cell with a dual-functional MoO_X layer has the potential to provide a viable pathway for developing high-efficiency tandem devices. Full article

Constructing an S-type heterojunction to promote photogenerated carrier separation is a valid method to ameliorate this problem. In this work, self-assembled perylenetetracarboxylic diimide (PDI) was modified on the surface of two-dimensional (2D) BiOBr nanosheets using a continuous ion layer adsorption method. To explore its microstructure, photoelectric properties, and other characteristics, the electron transport channel constructed between self-assembled PDI and BiOBr hinders photogenerated electron-hole recombination. Under visible light irradiation, when the rhodamine B (RhB) was 50 mg/L, the removal rate over 1/3 PDI/BiOBr reached 98% in 60 min, and the rate constant was 15.9 times that over self-assembled PDI and 13 times that over BiOBr. In degrading methyl orange (MO), the removal rate over 1/3 PDI/BiOBr was 65.8% in 60 min, and the rate constant was 5.7 times that over self-assembled PDI and 3.4 times over BiOBr. After the ESR test, O₂⁻ is proved to be the main active species in the reaction. Full article

The rational design of heterojunction photocatalysts enabling fast transportation and efficient separation of photoexcited charge carriers is the key element in visible light-driven photocatalyst systems. Herein, we develop a unique Z-scheme heterojunction consisting of NiMoO₄ microflowers (NMOF) and ZIF67, referred to as ZINM (composite), for the purpose of antibiotic degradation. ZIF67 was produced by a solution process, whereas NMOF was synthesized via coprecipitation with a glycine surfactant. The NMOF exhibited a monoclinic phase with a highly oriented, interconnected sheet-like morphology. The ZINM showed better optical and charge transfer characteristics than its constituents, ZIF67 and NiMoO₄. Consequently, the developed heterojunction photocatalysts exhibited superior photocatalytic redox capability; the ZINM30 (the composite with 30 wt.% of NiMoO₄ loaded) could degrade 91.67% of tetracycline and 86.23% of norfloxacin within 120 min. This enhanced photocatalytic activity was attributable to the reduced bandgap (E_gap = 2.01 eV), unique morphology, high specific surface area (1099.89 m²/g), and intimate contact between ZIF67 and NiMoO₄, which facilitated the establishment of the Z-scheme heterojunction. Active species trapping tests verified that •O₂⁻ and h⁺ were the primary species, supporting the proposed degradation mechanism. This work highlights a valid Z-scheme ZIF67/NiMoO₄ heterojunction system for efficient carrier separation and, therefore, enhanced photocatalytic degradation of antibiotics. Full article

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. Full article

In order to utilize the longer wavelength light, the surface sulfurization of MoO₃ was carried out. The photocurrent responses to typical 650, 808, 980, and 1064 nm light sources with Au gap electrodes were investigated. The results showed that the surface S–O exchange of MoO₃ improved the interfacial charge transfer in the range of the broadband light spectrum. The S and O can be exchanged on the surface of MoO₃ nanosheets under the hydrothermal condition, leading to the formation of a surface MoO_x/MoS₂ heterojunction. The interfacial interaction between the MoO₃ nanosheets and MoS₂ easily generated free electrons and holes, and it effectively avoided the recombination of photogenerated carriers. Meanwhile, the surface S-doping of MoO₃ also resulted in the generation of an oxygen vacancy and sulfur vacancy on MoO_3−xS_2−y. The plasmonic characteristics of MoO_3−x contributed to the enhancement of the interfacial charge transfer by photoexcitation. Otherwise, even with zero bias applied, a good photoelectric signal was still obtained with polyimide film substrates and carbon electrodes. This indicates that the formation of the heterojunction generates a strong built-in electric field that drives the photogenerated carrier transport, which can be self-powered. This study provides a simple and low-cost method for the surface functionalization of some metal oxides with a wide bandgap. Full article

Organic/Si hybrid solar cells have attracted considerable attention for their uncomplicated fabrication process and superior device efficiency, making them a promising candidate for sustainable energy applications. However, the efficient collection and separation of charge carriers at the organic/Si heterojunction interface are primarily hindered by the inadequate work function of poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS). Here, the application of a high-work-function MoO₃ film onto the n-Si/PEDOT:PSS surface leads to a notable enhancement in the device’s built-in potential. This enhancement results in the creation of an inversion layer near the n-Si surface and facilitates charge separation at the interface. Simultaneously, it inhibits charge recombination at the heterojunction interface. As a result, the champion PEDOT:PSS/Si solar cell, which incorporates a MoO₃ interface layer, demonstrates an efficiency of 16.0% and achieves a high fill factor of 80.8%. These findings provide a straightforward and promising strategy for promoting the collection and transmission of charge carriers at the interface of photovoltaic devices. Full article

In this study, a hollow tubulous-shaped In₂O₃ derived from MIL (MIL-68 (In)) exhibited an enhanced specific surface area compared to MIL. To further sensitize In₂O₃, ZnIn₂S₄ was grown in situ on the derived In₂O₃. The 40In₂O₃/ZnIn₂S₄ composite (1 mmol ZnIn₂S₄ loaded on 40 mg In₂O₃) exhibited degradation rates of methyl orange (MO) under visible light (80 mW·cm⁻², 150 min) that were 17.9 and 1.4 times higher than those of the pure In₂O₃ and ZnIn₂S₄, respectively. Moreover, the 40In₂O₃/ZnIn₂S₄ exhibited an obviously improved antibacterial performance against Pseudomonas aeruginosa, with an antibacterial rate of 99.8% after visible light irradiation of 80 mW cm⁻² for 420 min. The 40In₂O₃/ZnIn₂S₄ composite showed the highest photocurrent density, indicating an enhanced separation of photogenerated charge carriers. Electron spin resonance results indicated that the 40In₂O₃/ZnIn₂S₄ composite generated both ·O₂⁻ and ·OH radicals under visible light, whereas ·OH radicals were almost not detected in ZnIn₂S₄ alone, suggesting the presence of a Z-scheme heterojunction between In₂O₃ and ZnIn₂S₄, thereby enhancing the degradation and antibacterial capabilities of the composite. This offers fresh perspectives on designing effective photocatalytic materials for use in antibacterial and antifouling applications. Full article

Zinc oxide (ZnO) nanoparticles, as a non-toxic, harmless, and low-cost photocatalytic material, have attracted much attention from the scientific and industrial communities. However, due to their small particle size and high surface energy, ZnO nanoparticles are prone to agglomeration. In addition, ZnO nanoparticles only have catalytic activity and electron–hole pairing under ultraviolet light. Therefore, Copper(I) oxide (Cu₂O)-ZnO/cellulose composites with excellent photocatalytic performance were fabricated by loading Cu₂O crystals and using cellulose fiber substrate in this work. Cu₂O can increase the light absorption range (including ultraviolet light and visible light) of ZnO/cellulose composites. Moreover, Cellulose fibers can improve the contact area to pollution and photostability of the Cu₂O/ZnO nanoparticles, thereby enhancing the photocatalytic activity. The Cu₂O-ZnO/cellulose composite showed the highest photocatalytic activity for Methyl orange (MO) degradation, which was approximately 40% and 10% times higher than those of the ZnO/cellulose and Cu₂O/ZnO composites, respectively. Moreover, the degradation rate of phenol reached 100% within 80 min. The highly enhanced activity of the Cu₂O-ZnO/cellulose composite is attributed to the enlargement of the light absorption range and the formation of heterojunctions between the counterparts, which effectively suppress the recombination of the photogenerated charge carriers. Overall, this work aims to improve the photocatalytic activities of ZnO/cellulose composites by loading Cu₂O crystals, hoping to provide a novel and efficient photocatalyst for wastewater treatment. Full article

The development of low-cost and low-power gas sensors for reliable NO₂ gas detection is important due to the highly toxic nature of NO₂ gas. Herein, initially, SnO₂ nanowires (NWs) were synthesized through a simple vapor–liquid–solid growth mechanism. Subsequently, different amounts of SnO₂ NWs were composited with MoS₂ nanosheets (NSs) to fabricate SnO₂ NWs/MoS₂ NS nanocomposite gas sensors for NO₂ gas sensing. The operation of the sensors in self-heating mode at 1–3.5 V showed that the sensor with 20 wt.% SnO₂ (SM-20 nanocomposite) had the highest response of 13 to 1000 ppb NO₂ under 3.2 V applied voltage. Furthermore, the SM-20 nanocomposite gas sensor exhibited high selectivity and excellent long-term stability. The enhanced NO₂ gas response was ascribed to the formation of n-n heterojunctions between SnO₂ NWs and MoS₂, high surface area, and the presence of some voids in the SM-20 composite gas sensor due to having different morphologies of SnO₂ NWs and MoS₂ NSs. It is believed that the present strategy combining MoS₂ and SnO₂ with different morphologies and different sensing properties is a good approach to realize high-performance NO₂ gas sensors with merits such as simple synthesis and fabrication procedures, low cost, and low power consumption, which are currently in demand in the gas sensor market. Full article