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Sulfur-doped porous graphitic carbon nitride heterojunction hybrids for enhanced photocatalytic H2 evolution
摘要： Graphitic carbon nitride (g-C3N4) is considered as an attractive, efficient and newly generated photocatalyst material owing to its distinct properties such as metal free, suitable band gap and high physicochemical stability. Nevertheless, the photocatalytic activity of pure g-C3N4 was limited by the fast recombination rate of photoinduced electron–hole pairs and relatively low specific surface area. In this study, we provide a new prospect to overcome the problem by using another suitable precursor urea-assisted copolymerization with thiourea which is expected to optimize the process of thermal condensation, inhibit agglomeration and improve the specific surface area; meanwhile, the formed isotype heterogeneous junction effectively inhibits charge carrier recombination. The formed g-C3N4 isotype heterojunction photocatalyst manifested significant improvement photocatalytic hydrogen production than the single and pure g-C3N4 sample. This significant enhanced photocatalytic performance is mainly ascribed to inhibited recombination, enriched active site and enlarged specific surface area.
关键词： porous graphitic carbon nitride,heterojunction hybrids,photocatalytic H2 evolution,Sulfur-doped
更新于2025-09-23 15:21:21
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Green Synthesis and Electrical Properties of p-CuO/n-ZnO Heterojunction Diodes
摘要： Green production of nanomaterials and their materials properties studies are majorly important for the futuristic development of nanodevices. We had green synthesized the ZnO and CuO nanoparticles using the extract of “Eucalyptus globulus” leaves. The obtained ZnO and CuO nanoparticles were studied for their structural, morphological and optical properties. The green synthesized CuO and ZnO nanoparticles have showed the crystalline size of about 12.29 and 10.16 nm. The transmission electron microscopic images of green synthesized ZnO and CuO nanoparticles revealed the morphological information and their respective average sizes of 46 and 32 nm. Optical absorbance spectrum revealed the existence of morphology based quantum confinement in the green ZnO and CuO nanoparticles. Further we have fabricated the p-CuO/n-ZnO heterojunction device using the green synthesized nanoparticles and also evaluated the electrical properties of the p–n junction diode. Under the light illumination the photodiode characteristic were studied for the obtained p–n junction diode. Finally, the energy band diagram of the photodiode responsible for the electronic transport had also discussed.
关键词： Electrical properties,p–n Heterojunction,Green synthesis,Photodiode
更新于2025-09-23 15:21:21
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CuO/ZnO Heterojunction Nanoarrays for Enhanced Photoelectrochemical Water Oxidation
摘要： Photoelectrochemical (PEC) water splitting offers a promising route for producing chemical energy from abundant solar energy, but a bottleneck remains for PEC practical applications because of the lack of efficient, stable and earth-abundant photoelectrodes. Here, we report simultaneous improvements in carrier separation and light harvesting by constructing p-n heterojunctions in CuO/ZnO nanorod arrays. The novelty of this work is developing a new strategy for preparing a CuO/ZnO p-n heterojunction photoanode for PEC water splitting, in which Cu(OH)2/ZnO is first prepared by a chemical solution strategy and then transformed into CuO/ZnO by annealing. The CuO/ZnO heterojunction photoanode exhibited a significant negative shift of 150 mV for the onset potential and an approximately 4-fold enhancement in the photocurrent at 1.23 V vs reversible hydrogen electrode (RHE) compared with those of pristine ZnO NRs. This work offers a facile strategy for preparing oxide-based p-n heterojunction photoanodes for enhanced PEC water splitting.
关键词： Water Splitting,Light Absorption,Photoelectrochemical (PEC),Heterojunction,Photoanode,P-N Junction
更新于2025-09-23 15:21:21
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Facile synthesis approach for core-shell TiO2–CdS nanoparticles for enhanced photocatalytic H2 generation from water
摘要： With the ambition to design a cost-effective and highly stable photocatalyst with improved photocatalytic activity towards H2 generation by water splitting, herein we report a two-step facile synthesis approach for core-shell structure of TiO2-CdS nanocomposites. The synthesized photocatalysts are comprehensively characterized by SEM, XRD, BET, UV-vis DRS, Photoluminescence and XPS to investigate the morphological, crystalline, structural, optical properties and surface analysis. The photocatalytic activity is evaluated by measuring the ability of TiO2-CdS to generate H2 gas by water splitting in the presence of hole scavengers under simulated solar light at AM 1.5G conditions. Our optimized sample TiO2-CdS (3:2) exhibited an enhanced photocatalytic activity by generating 954 μmol g-1 h-1 of hydrogen which is ~1.4 and ~1.7 times higher than pure CdS nanoparticles and pure TiO2, respectively. The optimized sample achieved an apparent quantum efficiency of 3.53% along with good stability by generating a similar amount of H2 for 40 consecutive hours. The enhanced photocatalytic activity and stability of the core-shell TiO2-CdS nanocomposite is attributed to the broader solar spectrum absorption, efficient photo-induced charge separation on the interface of TiO2-CdS due to the formation of heterojunction and high surface area with a large fraction of mesopores.
关键词： Photocatalytic H2 generation,Core-Shell TiO2-CdS nanocomposite,hydrothermal approach,CdS nanoparticles,Heterojunction
更新于2025-09-23 15:21:21
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Monte Carlo Modeling of the Diodes with Lateral Resonant Tunneling Border
摘要： Diodes with resonant tunneling border (RTB) are studied as possible high speed and wide-band devices. The diodes represent planar two-terminal n+-n-n+-GaAs-based structures containing lateral active border as a AlGaAs/GaAs double barrier resonant tunneling structure connected to anode contact. The 2-D model of electron transport in the device is proposed. The analysis of the diodes operation was performed using ensemble Monte Carlo technique. Transfer matrix approach for simulation of tunneling transfer is applied. The influence of parameters of the diode structure such as a position of RTB, a composition of AlGaAs barriers and a material doping on current – voltage characteristics of diode has been investigated. strong influence of contact size and geometry on the diode characteristic. The aim of the work is to construct an effective numerical 2D model used to consider electron transport at high frequencies with taking into account hot-carrier effects in cases where the mean free path is comparable to the device dimensions and electron tunneling processes are in place. The basis of the proposed model is ensemble Monte Carlo method [4]. The other model elements are chosen by obtaining accurate physical results per reasonable time.
关键词： negative voltage current differential resistance,characteristics,heterojunction,quantum well,resonant tunneling border
更新于2025-09-23 15:21:21
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Effective Removal of Tetracycline by Using Bio-Templated Synthesis of TiO2/Fe3O4 Heterojunctions as a UV–Fenton Catalyst
摘要： Novel maize-straw-templated TiO2/Fe3O4 hierarchical porous composites were synthesized by high-temperature calcination followed by a hydrothermal process. The composites were demonstrated to be efficient heterogeneous catalysts for the UV–Fenton-like degradation of TC. The results show that the as-prepared TiO2/Fe3O4 catalysts retain the original pore morphology of the maize-straw material, and a large amount of Fe3O4 particles are attached to the TiO2 surfaces. The as-prepared TiO2/Fe3O4 heterojunctions have abundant interfacial boundaries, which greatly improve the migration of photoexcited charges across different components. Consequently, in the UV–Fenton system, the TiO2/Fe3O4 catalysts exhibit significant activity towards the degradation of TC (50?mg/L) in a wide pH range. In particular, a maximum mineralization and TC removal of 98% is achieved within 60?min at pH 7.0, which is much higher than that of traditional Fe3O4-based UV–Fenton (81%) and TiO2 photocatalysis (23%). The enhanced degradation and mineralization of tetracycline is attributed to the efficient reduction of Fe3+ to Fe2+ by photo-generated electrons from the TiO2 skeleton of the TiO2/Fe3O4 heterojunction.
关键词： UV–Fenton,Biotemplated,TiO2/Fe3O4 heterojunction,Tetracycline degradation
更新于2025-09-23 15:21:21
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The synthesis of graphene-TiO2/g-C3N4 super-thin heterojunctions with enhanced visible-light photocatalytic activities
摘要： In this paper, an efficient strategy for the synthesis of graphene nanobelt-titanium dioxide/graphitic carbon nitride (graphene-TiO2/g-C3N4) heterostructure photocatalyst was applied to fabricate a kind of visible-light-driven photocatalyst. The heterostructure shows higher absorption edge towards harvesting more solar energy compared with pure TiO2 and pure g-C3N4 respectively. Furthermore, the as-prepared graphene-TiO2/g-C3N4 heterostructure can show enhanced photocatalytic activity under visible-light irradiation. These outstanding performances of photocatalytic activities for graphene-TiO2/g-C3N4 composites can be attributed to the heterojunction interfaces which can separate the electron-hole pairs and impede the recombination of electrons and holes more efficiently. This study conclusively demonstrates a facile and environmentally friendly new strategy to design highly efficient graphene-TiO2/g-C3N4 heterostructure photocatalytic materials for potential applications under visible-light irradiation.
关键词： Visible light,Heterojunction,Nanostructured catalysts,Graphene,Photocatalytic activity
更新于2025-09-23 15:21:21
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Performance analysis of c-Si heterojunction solar cell with passivated transition metal oxides carrier-selective contacts
摘要： Transition metal oxides (TMOs) as passivating carrier-selective contact layers are investigated for silicon heterojunction solar cells. MoOx as hole-selective layer and TiOx as an electron-selective layer are explored in detail to design a high-efficiency silicon heterojunction solar cell without any specified surface passivation layer. The thickness and optical transparency of the MoOx hole-selective layer have been evaluated through optical simulation. The impact of TMOs’ work function and their passivation quality has been examined in detail to extract the maximum conversion efficiency from silicon heterojunction solar cells. To increase the optical absorption in c-Si, the micro–nanopillar structure has also been implemented. It has been found that the barrier height at the TMO/silicon heterocontact plays a significant role in the overall performance improvement of the solar cell. The optimized cell design without doping and separate passivating layer can achieve a power conversion efficiency of ~ 22%. Our findings open the potential pathways and opportunities to obtain simplified heterojunction solar cells at lower temperatures and without impurity doping.
关键词： Surface recombination velocity,Carrier-selective contact layers,Transition metal oxides,c-Si heterojunction solar cells
更新于2025-09-23 15:21:01
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Lead-free perovskite/organic semiconductor vertical heterojunction for highly sensitive photodetectors
摘要： In recent years, photodetectors based on organic-inorganic lead halide perovskites have been studied extensively. However, the inclusion of lead in those materials can cause severe human health and environmental problems, which is undesirable for practical applications. Here, we report high-performance photodetectors with a tin-based perovskite/PEDOT:PSS vertical heterojunction. The device demonstrates broadband photo-response from NIR to UV. The maximum responsivity and gain are up to 2.6 × 106 A/W and 4.7 × 106, respectively. Moreover, a much shorter response time and higher detectivity can be achieved by reducing the thickness of PEDOT:PSS. The outstanding performance is due to the excellent optoelectronic properties of the perovskite and the photo-gating effect originated from the heterojunction. Furthermore, devices fabricated on flexible substrates can demonstrate not only high sensitivity but also excellent bending stability. This work opens up the opportunity of using lead-free perovskite in highly sensitive photodetectors with vertical heterojunctions.
关键词： Photo-gating,heterojunction,organic semiconductors,Photodetectors,Lead free perovskites
更新于2025-09-23 15:21:01
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1D/2D WO3 nanostructure coupled with nanoparticulate CuO cocatalyst for enhancing solar-driven CO2 photoreduction: The impact of the crystal facet
摘要： Photocatalytic reduction of CO2 into solar fuels is regarded as one of the most promising approaches to address the issues of global warming and the energy crisis. The promotion of spatial charge separation and transfer through crystal facet engineering could be conducive to improved photocatalytic activity. In this study, one-dimensional (1D) WO3 nanowires with a {110} dominant facet (WO3-110) and two-dimensional (2D) WO3 nanosheets with a {001} dominant facet (WO3-001) coupled with CuO nanoparticles are fabricated by a facile method and used for CO2 photoreduction. Its composition and structural characterizations suggest that the WO3-CuO hybrid features good contact between the WO3 and CuO nanostructures. Under light irradiation, the WO3 and WO3-CuO nanostructures are able to photoreduce CO2 into CH4. Notably, the prepared WO3-CuO nanohybrids with different exposed facets show improved CO2 reduction capability compared to pure WO3 and CuO. The heterojunction interface between the WO3 photocatalyst and the CuO cocatalyst through p-n contact can facilitate electron-hole pair separation and accordingly results in enhanced photocatalytic performance. With the assistance of the CuO cocatalyst, the {110} facet WO3-CuO hybrid displays superior photoreduction capability compared to the {001} facet WO3-CuO, which is attributed to the difference in the crystal facets in the heterostructure. The {110} facet WO3 nanowires have a more negative conduction band edge, contributing to the higher reduction capacity of this sample. On the other hand, it is shown that faster charge carrier transfer efficiency would enable more photoinduced electrons to participate in CO2 photoreduction, especially with the involvement of the nanoparticulate CuO cocatalyst. This work provides guidance for designing a hetero-photocatalyst-cocatalyst system through crystal facet engineering.
关键词： WO3-CuO composite,CO2 Photoreduction,1D/2D WO3 nanostructures,heterojunction,crystal facet impact
更新于2025-09-23 15:21:01