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Carbon-based Materials have been extensively researched for their prospect in the fields of environment and energy, especially for graphene oxide (GO). In this work, a novel sodium dodecyl sulfate (SDS)-assisted synthesis of BiOBr/Bi2WO6/GO ternary composite has been synthesized successfully by a handy hydrothermal method. Photoluminescence, Photocurrent, Electrochemical Impedance Spectroscopy, surface photovoltage and transient photovoltage measurements illustrate that construction of p-n BiOBr/Bi2WO6 heterojunction leads to the obviously enhancement of charge separation efficiency, and the photogenerated electrons trapped by GO can effectively inhibit the recombination process of photogenerated charge, resulting in the improvement of charge separation efficiency and the longer lifetime of photogenerated carriers for BiOBr/Bi2WO6/GO. The characterization of structure and morphology indicate that role of GO can also improve the visible light absorption range, and the SDS-assisted synthesis can reduce the size of particle in the composite and enhances the specific surface area of the composite by regulating the particle size and agglomeration. Under optimal conditions, BiOBr/Bi2WO6/GO (SDS) has the outstanding photocatalytic degradation performance and the degradation rate constants for oxytetracycline, tetracycline hydrochloride, methylene blue and rhodamine are 0.056, 0.057, 0.103 and 0.414 min−1, respectively. Notably, the degradation rate constants obtained by BiOBr/Bi2WO6/GO (SDS) are more ten times higher than that of pure BiOBr and Bi2WO6. The possible mechanism of photocatalytic degradation was suggested for BiOBr/Bi2WO6/GO based on the dynamic properties of photogenerated charge and reactive oxidation species results. Surprisingly, the recyclability of the BiOBr/Bi2WO6/GO (SDS) composite obtained from the cyclic experiments has laid a foundation for the study of efficient and stable photocatalysts. [ABSTRACT FROM AUTHOR]

Heterostructured photocatalysts represent an essential role in the catalytic redox reactions in wastewater during illumination. In this contribution, p-n heterojunction PdO/CeO 2 photocatalysts were constructed with enhanced photocatalytic ability for the reduction of Hg(II) utilizing HCOOH as hole scavengers under visible light. PdO NPs were uniformly spread on the mesoporous CeO 2 surface, to act as potential separation centers of electrons and holes. The synthesized PdO/CeO 2 nanocomposites exhibited an excellent photocatalytic ability, contrasted to the bare CeO 2 NPs. The photocatalytic ability of PdO/CeO 2 nanocomposites for reduction of Hg(II) has existed in the trends of 2%PdO ≥1.5%PdO >1%PdO >0.5 % PdO/CeO 2 nanocomposites > bare CeO 2 NPs. A photocatalytic ability of 100 % for Hg(II) reduction was achieved within 40 min utilizing 1.5 % PdO/CeO 2 nanocomposites, which was 2.2 folds greater than that of bare CeO 2 NPs. The rate constant of 1.5 % PdO/CeO 2 nanocomposite (0.106 min−1) is more 9.9 times than that CeO 2 NPs (0.0107 min−1). The enhancement photocatalytic ability of PdO/CeO 2 can be interpreted to the wide surface area, narrow bandgap, numerous active sites, fast mobility, efficient diffusion of Hg(II), and the high separation rate of photocarriers. Considering the promotion photocatalytic ability of heterojunction PdO/CeO 2 nanocomposites, the heterostructure photocatalyst is of magnificent importance to the photocatalytic redox reactions and exhibits a significant effect on our human health and ecological environment. [ABSTRACT FROM AUTHOR]

Ethylene glycol (EG) is a widely used material, but its vapor is harmful to human health already in low concentrations. Thus, highly sensitive EG gas sensors are urgently needed. Herein, a series samples of ZnO and carbon dots (CDs) were synthesized at different ratios through a simple mechanical grinding method. The senor made using ZnO/CDs2 exhibits an ultra-high response (Ra/Rg) to 100 ppm EG up to 2798, 1378 and 467, and extremely low detection limit as low as 21 ppb, 13 ppb and 2 ppb, under UV light, visible light, and infrared light, respectively, as well as excellent repeatability and long-term stability. Especially, under UV light irradiation, the response of ZnO/CDs2 to 100 ppm EG is 24 times that of pure ZnO (Ra/Rg = 114.7), and more than 71 times that of 9 other gases. The outstanding gas sensing performance of ZnO/CDs2 can be attributed to the excellent light response ability of CDs at first, which greatly enriches the electron concentration in ZnO/CDs under light irradiation. Furthermore, the photo-induced electron transfer (PET) property of CDs and the p-n heterojunction formed at the interface between ZnO and CDs play a key role in rapid electron transport and transfer, avoiding a large number of electron hole recombination. [ABSTRACT FROM AUTHOR]

In-situ heterojunction transformation is proposed to enhance the built-in electric field, which promotes charge redistribution, modulates the electronic structure, optimizes the free energy of the intermediate, ultimately achieves efficient water splitting. This is exemplified by constructing Ag 2 S@S/NiFe-LDH (p-n heterojunction) and Ag@S/NiFe-LDH (M−S heterojunction). [Display omitted] The construction and regulation of built-in electric field (BIEF) are considered effective strategies for enhancing the oxygen evolution reaction (OER) performance of transition metal-based electrocatalysts. Herein, we present a strategy to regulate the electronic structure of nickel–iron layered double hydroxide (NiFe-LDH) by constructing and enhancing the BIEF induced by in-situ heterojunction transformation. This concept is demonstrated through the design and synthesis of Ag 2 S@S/NiFe-LDH (p-n heterojunction) and Ag@S/NiFe-LDH (Mott-Schottky heterojunction). Benefiting from the larger BIEF of Mott-Schottky heterojunction, efficient electron transfer occurs at the interface between silver (Ag) and NiFe-LDH. As a result, Ag@S/NiFe-LDH exhibits excellent OER performance, requiring only a 232 mV overpotential at 1 M KOH to achieve a current density of 100 mA cm−2, with a small Tafel slope of 73 mV dec-1, as well as excellent electrocatalytic durability. Density functional theory (DFT) calculations further verified that stronger BIEF in Mott-Schottky heterojunction enhances the electron interaction at the interfaces, reduces the energy barrier for the rate-determining step (RDS), and accelerates the OER kinetics. This work provides an effective strategy for designing catalyst with larger BIEF to enhance electrocatalytic activity. [ABSTRACT FROM AUTHOR]

The present work is devoted to the synthesis of perovskite LaAlO 3 by Sol-Gel approach and its application for the photo-evolution of H 2 in conjunction with cobalt ferrite CoFe 2 O 4 prepared by nitrate route. The thermal analysis (TG/DSC) showed that the formation is completed at 600 °C. The X-ray diffraction (XRD) pattern is characteristic of a single phase, crystallizing in a rhombohedral symmetry with a crystallite size of 36 nm. The SEM micrographs revealed a homogeneous structure with an agglomeration of shaped grains (40–80 nm). The forbidden band (3.39 eV), calculated from diffuse reflectance data, is assigned to the ligand charge transfer O2−: 2p → Al3+: 3s orbital. As prepared, LaAlO 3 is an n -type semiconductor as demonstrated from the capacitance - potential (C−2 - E) graph with an electron density of 9.4 × 1014 cm−3 due to oxygen under-stoichiometry. Attention was directed to photo-electrochemistry in connection with water reduction into hydrogen. With a negative conduction band potential (−0.11 V SCE), H 2 generation can be synergized over the hetero-system by visible light. The photocatalytic capability of CoFe 2 O 4 25%/LaAlO 3 revealed a high H 2 generation of 963 μmol g−1 in the alkaline electrolyte (NaOH, 0.1 M) with a catalyst dose of 1 mg mL−1, which is 1.3 times more than CoFe 2 O 4 under similar conditions. Photoactivity is significantly improved by 60%, up to 2400 μmol g−1 in the presence of oxalate C 2 O 4 2− as a hole scavenger in the hetero-junction, two hydrogen release tests were successfully recorded. The higher H 2 production in the hetero-junction system is attributed to the lower recombination rate of electron/hole (e−/h+) in the material, due to the large band bending at the solid interfacial. [Display omitted] • The perovskite LaFeO 3 nanoparticle was prepared using a sol-gel method with nitrate precursors. • The heterogeneous nanocomposites CoFe 2 O 4 /LaAlO 3 were prepared using a simple mechanical method. • The conduction band (−0.11 V SCE) of LaAlO 3 suggests H 2 formation in the LaAlO 3 /CoFe 2 O 4 system. • The photocatalytic capability of CoFe 2 O 4 25%/LaAlO 3 75% showed high H 2 generation, reaching 963.10 μmol/g without a scavenger. • Photoactivity is significantly improved by 60%, reaching up to 2400 μmol/g in the presence of oxalate (C 2 O 4 2−) as a hole scavenger in the CoFe 2 O 4 25%/LaAlO 3 75% system. [ABSTRACT FROM AUTHOR]

To optimize the performance of photocatalytic H 2 production, many effective methods have been developed, such as controlling morphology, designing synergetic reaction, and enhancing the utilization of photogenerated charge carriers (PCCs). In this work, an efficient CoMoO 4 /Zn 0.3 Cd 0.7 S (CMO/ZCS) photocatalyst with p-n heterojunction was constructed by incorporating Zn 0.3 Cd 0.7 S (ZCS) nanoparticles into CoMoO 4 (CMO) microflowers. Although CMO had limited activity in H 2 production under visible light irradiation, it could largely boosting the H 2 production efficiency of ZCS nanoparticles by oxidizing p-chlorobenzyl alcohol (Cl-PhCH 2 OH) in organic solvent. In the CMO/ZCS composites, the best rates of H 2 and Cl-PhCHO reached 34.28 and 35.87 mmol g−1 h−1, respectively. The p-n heterojunction formed between CMO and ZCS may be the main enhanced reason of the excellent performance, as it could effectively improve the separation, transfer and utilization of PCCs. The design of the CMO/ZCS catalyst not only optimizes the migration and utilization of PCCs, but also provides crucial theoretical guidance and experimental insights for the development of highly efficient photocatalysts. [Display omitted] • CoMoO 4 /Zn 0.3 Cd 0.7 S heterojunction was prepared by self-assembly method. • Zn 0.3 Cd 0.7 S nanoparticles are incorporated into CoMoO 4 microflowers. • p-n heterojunction improves the transfer of photogenerated charge carriers. • Photocatalytic H 2 evolution is promoted by 4-chlorobenzyl alcohol oxidation. [ABSTRACT FROM AUTHOR]

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 (YVO 4) is grown via an adapted sol-gel process tracked by loading of 1.0–4.0 wt% of silver oxide (Ag 2 O) to form heterojunction nanocomposite of Ag 2 O/YVO 4. The as-prepared heterostructures were applied for visible-light photoelimination of ciprofloxacin (CF) in water. The presence of Ag 2 O has enhanced both light absorbance and photogenerated carrier separation of YVO 4. The 3.0 to 4.0 wt% loading of Ag 2 O designated the thinnest bandgap of 2.4 eV regardless of the minor decrease in their specific surface areas from 220 in bare YVO 4 to 168 m2 g−1 for 3.0 % Ag 2 O/YVO 4. The complete mineralization of CF over 3.0 % Ag 2 O/YVO 4 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 Ag 2 O/YVO 4. [ABSTRACT FROM AUTHOR]

The band offsets of semiconductor heterojunctions are critical parameters for the design of electronic and optoelectronic devices. In this work, we report the fabrication of a Co3O4/3C-SiC p-n heterojunction and the determination of the conduction band and valence band offsets at the Co3O4/3C-SiC heterojunction. Our results reveal that the Co3O4/3C-SiC p-n heterojunction exhibits a type-II band alignment, with a conduction band offset of 0.75 eV and a valence band offset of 0.96 eV. These experimental findings are crucial for the design and development of 3C-SiC devices for electronic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

We report the diode characteristics of solution-processed p-n heterojunction formed by NiO and copper-doped NiO with an aluminum-doped ZnO layer (AZO). The pure and copper-doped NiO thin films annealed at 300 °C and 450 °C are amorphous and crystalline, respectively. Their optical bandgap increased with Cu substitution and annealing temperature. It caused a substantial difference in the rectifying behavior of the Schottky junction due to different current transport mechanisms attributed to lattice mismatch, barrier tunneling, radiative recombination, and variations in the interface composition. The heterojunction of Cu:NiO film (annealed at 300 °C) with AZO exhibited a high rectification due to the direct tunneling of electrons and holes without radiative recombination. However, the heterojunction of the p-type film annealed at 450 °C exhibited very weak rectification ascribed to accelerated radiative recombination of electrons and holes in the depletion region. [ABSTRACT FROM AUTHOR]

Semiconductor heterostructure composite materials, exemplified by p-n junctions, have garnered substantial interest for their elevated ionic conductivity, crucial in solid oxide fuel cells (SOFCs). The inherent built-in electric field (BIEF) within these materials enhances ion transport while hindering electron flow, thereby mitigating the risk of short circuits. This research focuses on the electronic conduction properties of p-n junctions, specifically through the development of high-performance LiCo 0.5 Al 0.5 O 2 (LCAO)-Ce 0.8 Sm 0.2 O 2-δ (SDC) semiconductor heterojunction composite electrolytes for low-temperature solid oxide fuel cells (LT-SOFCs). Experimental results demonstrate a correlation between the electrolyte's performance and the LCAO to SDC weight ratio. The SOFC equipped with a 3LCAO-7SDC electrolyte achieved an open-circuit voltage (OCV) of 1.1 V and a maximum power density (MPD) of 1013 mW/cm2 at 550 °C, significantly outperforming other composite ratios and single-phase SDC electrolytes, which only reached 453 mW/cm2 under identical conditions. High-resolution transmission electron microscopy (HRTEM) revealed the presence of non-uniform interfaces within these composites. Energy band structure analyses confirm superior ionic conductivity and effective charge separation capabilities. This study introduces a novel p-n junction design for LT-SOFC electrolyte materials using LCAO-SDC, further advancing the exploration of p-n junctions in this application. • Design of LiCo 0.5 Al 0.5 O 2 -Ce 0.8 Sm 0.2 O 2-δ electrolyte based on p-n heterojunction. • Fuel cells were manufactured and tested based on this composite. • The SOFC exhibited considerable performances of 367–1013 mW/cm2 at low temperatures. • Provided new insights and references for innovative energy technologies in fuel cells. [ABSTRACT FROM AUTHOR]

Pure tin oxide (SnO2) as a typical conductometric hydrogen sulfide (H2S) gas-sensing material always suffers from limited sensitivity, elevated operation temperature, and poor selectivity. To overcome these hindrances, in this work, hollow CuO-SnO2 nanotubes were successfully electrospun for room-temperature (25 °C) trace H2S detection under blue light activation. Among all SnO2-based candidates, a pure SnO2 sensor showed no signal, even toward 10 ppm, while the 1% CuO-SnO2 sensor achieved a limit of detection (LoD) value of 2.5 ppm, a large response of 4.7, and a short response/recovery time of 21/61 s toward 10 ppm H2S, as well as nice repeatability, long-term stability, and selectivity. This excellent performance could be ascribed to the one-dimensional (1D) hollow nanostructure, abundant p-n heterojunctions, and the photoelectric effect of the CuO-SnO2 nanotubes. The proposed design strategies cater to the demanding requirements of high sensitivity and low power consumption in future application scenarios such as Internet of Things and smart optoelectronic systems. [ABSTRACT FROM AUTHOR]

In this research, we report an enhanced sensing response ethanol gas sensing device based on a ternary nanocomposite of molybdenum diselenide-zinc oxide heterojunctions decorated rGO (MoSe2/ZnO/rGO) at room temperature. The sensing performance of the ternary nanocomposite sensing device has been analysed for various concentrations of ethanol gas (1–500 ppm). The gas-sensing results have revealed that for 500 ppm ethanol gas concentration, the sensing device has exhibited an enhanced response value ( R g / R a ) of 50.2. Significantly, the sensing device has displayed a quick response and recovery time of 6.2 and 12.9 s respectively. In addition to this, the sensing device has shown a great prospect for long-term detection of ethanol gas (45 days). The sensing device has demonstrated the ability to detect ethanol at remarkably low concentrations of 1 ppm. The enhanced sensing performance of the ternary nanocomposite sensing device has highlighted the effective synergistic effect between MoSe2 nanosheets, ZnO nanorods, and rGO nanosheets. This has been attributed to the formation of two heterojunctions in the ternary nanocomposite sensor: a p-n heterojunction between MoSe2 and ZnO and a p-p heterojunction between MoSe2 and rGO. The analysis of the results has suggested that the proposed MoSe2/ZnO/rGO nanocomposite sensing device could be considered a promising candidate for the real-time detection of ethanol gas. [ABSTRACT FROM AUTHOR]

Developing efficient photoelectrocatalysts is seen as a promising method for generating hydrogen through photoelectrochemical (PEC) water splitting. In this study, the WO 3 /Co 3 O 4 heterojunction was fabricated on FTO substrates, serving as an effective photoanode for PEC water splitting. The p-type Co 3 O 4 nanoparticles were loaded onto n-type WO₃ nanorods to create a p-n heterojunction, thereby reducing charge recombination due to the internal electric field at the heterointerface. Under LED illumination (∼80 mW/cm2), the photocurrent density of the WO 3 /Co 3 O 4 photoanode reached 161.1 μA/cm2 at 1.23 V vs. RHE, which is 2.3 times higher than that of bare WO 3 photoanode. The results show that loading Co 3 O 4 onto WO 3 nanorods significantly increased the absorption of visible light, boosted charge carrier density, and enhanced surface reaction kinetics. This work indicates the construction of p-n heterojunction photoanodes for achieving effective photoelectrochemical performance. [Display omitted] • The p-n WO 3 /Co 3 O 4 nanorods heterojunction is constructed. • The p-n heterojunction was used as a photoelectrocatalyst for water splitting. • The Co 3 O 4 nanoparticles substantially promote the charge separation and transfer. • The photoelectrochemical performance was enhanced due to the internal electric field. • Coating Co 3 O 4 onto WO 3 nanorods results in a porous surface on the photoanode. [ABSTRACT FROM AUTHOR]

In this study, a novel N, S-co-doped carbon-based Ag3PO4 composite photocatalyst (N,S-Ag3PO4@ACB) was synthesized using activated biochar (ACB) as a carrier and used for the efficient removal of norfloxacin (NOR), a typical bio-refractory antibiotic. We systematically investigated the degradation effects, actual wastewater treatment, the impacts of environmental factors, and the degradation pathways. The results show that N,S-Ag3PO4@ACB is essentially a p-n heterojunction with Z-scheme of Ag2S/Ag3PO4/ACB composite containing Ag nanoparticles. After 120 min of irradiation, N,S-Ag3PO4@ACB removed 90.42% of an initial NOR concentration of 50 mg L–1. The activation of graphitic N and the lone electron pairs of N and S, promoted rapid photogenerated charge transfer. Furthermore, the surface properties of ACB promoted free radicals generation, and the surface plasmon resonance effect of the Ag nanoparticles synergistically enhanced the photocatalytic activity. A new degradation intermediate of NOR was identified, and the degradation dynamics were elucidated with three main pathways. [ABSTRACT FROM AUTHOR]

TiO2 is a widely used photoelectric conversion semiconductor material. However, due to its native defects, such as the selective absorption of ultraviolet light and high recombination rate of photogenerated carriers, it exhibits poor photoelectrochemical (PEC) water splitting performance. In this study, intrinsic defect titanium vacancy and semiconductor recombination agents ZnIn2S4 were introduced into an anodization‐annealed TiO2 film (TiO2 NT) to enhance the photoanode activity. The activity‐enhanced TiO2 photoanode (ZIS@TiO2 NT‐EA) was characterized by surface analyses and photoelectrochemical measurements. Mott‐Schottky measurement indicated that the introduction of titanium vacancies into the TiO2 NT changed its semiconductor type from n to p, and significantly reduced its apparent activation energy if compared with the TiO2 NT. In addition, after the ZnIn2S4 nanoparticles were loaded on the TiO2 NT‐EA film, the carrier concentration of the ZIS@TiO2 NT‐EA was nearly 12 times higher than the pristine TiO2 NT. Due to the higher carrier separation efficiency resulting from the formation of p‐n heterojunction between TiO2 and ZnIn2S4, the photocurrent density of the ZIS@TiO2 NT‐EA reached 3.89 mA cm−2 at 1.23 V (vs. RHE), nearly 3 times higher than that of the original TiO2 NT. Amazingly, the maximum applied bias photon‐to‐current efficiency (ABPE) value of the ZIS@TiO2 NT‐EA photoanode reached 2.15 % at 0.496 V (vs. RHE), which is very competitive if compared with all the reported TiO2 film electrodes in the PEC water splitting application. The incident photon‐to current efficiency (IPCE) of the ZIS@TiO2 NT‐EA photoanode was approximately 40.9% at 300 nm, which was about 3 times higher than that of the TiO2 NT (13.6%). To understand these impressive improvements in water splitting, further analyses were conducted on the effect of the increased titanium vacancy concentration in the TiO2 lattice and the formation of p‐n junction between the TiO2 and ZnIn2S4 on the PEC behaviour, as well as on the charge transfer resistance and separation efficiency of carriers. [ABSTRACT FROM AUTHOR]

It is shown that replacing non-noble metals with noble metals in photocatalytic water splitting is pivotal for increased and sustained hydrogen production. However, the challenge persists in designing and developing a cost-effective, highly active catalyst with effective carrier separation and providing sufficient H+ reduction sites to enhance photocatalytic H 2 evolution efficiency. Herein, a series of S-scheme Cu 2 ZnSnS 4 /g-C 3 N 4 (CZTS/CN) heterojunction composites were prepared via the hydrothermal method, followed by comprehensive characterizations for in-depth investigation. The TEM image exhibits a clear interface, showing the heterojunction formation between CZTS and CN nanosheets. The results show that incorporating CZTS cocatalyst significantly improves CN photocatalytic hydrogen evolution reaction (HER) and its performance is notably influenced by CZTS to CN mass ratio. Among CZTS/CN heterojunction composites, the 5% CZTS/CN heterojunction composite exhibited a significantly improved HER of 243.64 μmol g−1h−1, which is 29.4 and 7.08 folds superior as compared to CN (8.29 μmol g−1h−1) and CZTS (34.42 μmol g−1h−1), respectively. The mechanism study revealed that the excellent superior H 2 evolution performance resulted from the established internal electric field (IEF) in p-n heterojunction, which expedites the efficient separation and migration of photoinduced carriers coupled with the distinctive flower-like configuration of CZTS offering a substantial surface area and enough active reduction sites for photocatalysis process. This work presents a rational design and an inexpensive and efficient heterojunction photocatalysis system suitable for diverse applications. • Cu 2 ZnSnS 4 /g-C 3 N 4 heterojunction composite was synthesized via a facile one-pot hydrothermal method. • S-scheme heterojunction composite shows excellent photocatalytic H 2 evolution rate (HER). • A built-in electric field to improves the separation of photoinduced carriers. • The construction of heterojunction improves the electron transport characteristics. • A suitable mechanism was proposed for improved photocatalytic performance. [ABSTRACT FROM AUTHOR]

One of the most promising approaches to addressing the current global energy and environmental crisis is the development and utilization of hydrogen energy. Photoelectrochemical (PEC) water splitting represents a clean and sustainable method for converting solar energy into hydrogen. In this article, we employed a hydrothermal-photodeposition method to fabricate Au@Pt decorated polyaniline (PANI)/TiO 2 (TNAP), which realized the synergy of p-n heterojunction and surface plasmon resonance (SPR). Experimental results revealed that p-n heterojunction can be formed between PANI and TiO 2 , whereas PANI can utilize visible light and the strong interaction between Au and PANI can realize the rapid transfer of hot electrons. Meanwhile, the outer layer Pt nanoparticles can accelerate water oxidation reaction kinetics. Therefore, the as-prepared TNAP exhibited the synergy promotion of p-n heterojunction and SPR effect, which is benefit for promoted light utilization and efficient charge transfer and separation. The optimized TNAP structure achieved hydrogen evolution rate of 19.26 μmol/cm2·h and photocurrent density of 1.20 mA/cm2 at a bias of 1.23 V vs. RHE, which is significantly higher than that of single semiconductor. This article suggests that the synergy promotion of SPR effect and p-n heterojunction is an efficient strategy to promote the efficiency of PEC water splitting. [Display omitted] • PANI/TiO 2 p-n heterojunction realizes the spatial separation of charge carriers. • Au NPs induced strong SPR effect and improve light utilization efficiency. • Strong interaction between PANI and Au promotes the transfer of hot electrons. • Surface Pt act as active sites and accelerate water oxidation reaction. • TNAP exhibited the synergy promotion of p-n heterojunction and SPR effect. [ABSTRACT FROM AUTHOR]

A highly sensitive and repeatable humidity sensor that can measure relative humidity at room temperature (25 °C) was fabricated using activated carbon-ZnO (AC/ZnO) nanocomposites. The AC/ZnO nanocomposites with high oxygen vacancies were prepared by a facile one-pot synthesis method through carbonization of ZnCl 2 -impregnated biomass precursor. The sensor exhibited a better response (96 % at 0.5 V biasing), short response time (17.4 s), and recovery time (32.1 s). The same 96 % relative response at 0.5V biasing for all four consecutive cycles was observed without losing the response-recovery time, indicating excellent repeatability. On the other hand, biomass-derived single-phase activated carbon (AC) did not respond to humidity change at room temperature. The improved humidity sensing in AC/ZnO nanocomposites was ascribed to the synergistic effects of increased oxygen vacancies, increased active sites in the AC phase, and the formation of p–n heterojunction at the composite interface, substantiated with X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS) studies. The sensing mechanism of AC/ZnO nanocomposite was discussed based on the enhanced reduction of H 2 O by adsorbed O 2 − at AC/ZnO heterojunction, leading to increasing sensor resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydrogen energy produced through photocatalytic water splitting is widely recognized as a viable solution to the depletion of non-renewable energy resources and ecological contamination concerns. This work designed and synthesized the MOF-derived hollow octahedral Co x P/MOF-801 p-n heterojunction photocatalyst. According to the result of hydrogen production test, the hydrogen production amount of Co x P/MOF-801-2 could reach 25.31 mmol g−1 under light irradiation for 5 h. The hollow octahedral structure and p-n heterojunction of the photocatalyst helped to enhance the light trapping ability and promote carrier transfer, resulting in improved performance of photocatalytic hydrogen production. To sum up, the design of hollow octahedral Co x P/MOF-801 photocatalyst effectively improved the photocatalytic hydrogen production performance. [Display omitted] • MOF-derived hollow octahedral MOF-801 was synthesized and modified with Co x P nanoparticles. • The p-n heterojunction inhibited the recombination of electrons and holes. • The Co x P/MOF-801 exhibited excellent hydrogen production activity and stability. [ABSTRACT FROM AUTHOR]

. A sandwich-type photoelectrochemical (PEC) immunosensor based on a ZnO/poly(5-formylindole) (P5FIn)/anthocyanin heterostructure was developed to achieve sensitive background-free detection of the tumor marker CYFRA21-1. ZnO with good photovoltaic properties is combined with narrow bandgap P5FIn to form a p-n type heterojunction. This structure reduces the electron–hole pair recombination, thereby enhancing the photocurrent response of the composite. Anthocyanidins are environmentally friendly natural compounds with excellent antioxidant, redox properties, and remarkable electrochemical activity. After sensitization by anthocyanins, the absorption and utilization of visible light in the composites are enhanced, further improving the PEC luminescence efficiency of the materials. Additionally, boron nitride quantum dots (BN QDs) are combined with Ab2 via polydopamine (PDA) as a secondary antibody marker, enhancing its sensitivity. The biosensor exhibited a linear detection range of 0.001–100 ng mL−1 with a limit of detection (LOD) of 0.00033 ng mL−1. Furthermore, this biosensor demonstrates excellent selectivity, reproducibility, and stability, as well as successful results in analyzing actual human serum samples. This approach provides a feasible method for tumor marker detection. [ABSTRACT FROM AUTHOR]

Owing to the synergistic effect of mesoporous structure, photo-to-heat conversion and photogenerated reactive oxygen species, the Co 3 O 4 /BiOCl nanocomposite exhibits excellent photothermal antimicrobial performance. [Display omitted] The overuse of antibiotics has caused the emergence of drug-resistant bacteria and even superbugs, which makes it imperative to develop promising antibiotic-free alternatives. Herein, a multimodal antibacterial nanoplatform of two dimensional/two dimensional (2D/2D) mesoporous Co 3 O 4 /BiOCl nanocomposite is constructed, which possesses the effect of "kill three birds with one stone": (1) the use of mesoporous Co 3 O 4 can enlarge the surface area of the nanocomposite and promote the adsorption of bacteria; (2) Co 3 O 4 displays remarkable full-spectrum absorption and photo-induced self-heating effect, which can raise the temperature of Co 3 O 4 /BiOCl and help to kill bacteria; (3) the p-type Co 3 O 4 and n -type BiOCl form a p-n heterojunction, which promotes the separation of photoelectrons and holes, thus producing more reactive oxygen species (ROS) for killing bacteria. The synergism of mesoporous structure, photothermal effect and photocatalytic ROS makes the developed Co 3 O 4 /BiOCl a promising antibacterial material, which shows outstanding antibacterial activity with an inhibition rate of nearly 100 % against Escherichia coli (E. coli) within 8 min. This work provides inspiration for designing multimodal synergistic nanoplatform for antibacterial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] The growing demand for clean and sustainable energy has driven extensive research into efficient photocatalysts for hydrogen production. However, many semiconductor photocatalysts in this field still face the challenges such as wide band gap, limited visible light absorption, and inefficient separation and transport of photoinduced charges. In this study, nickel–cobalt layered double hydroxide (NiCo-LDH) was synthesized using an "etch-and-grow" method with zeolitic imidazolate framework-67 (ZIF-67) as a sacrificial template, followed by high-temperature calcination to produce nickel–cobalt mixed metal oxide (NiCo-MMO). Zn 0.3 Cd 0.7 S quantum dots were used to modify NiCo-MMO resulting in a hollow dodecahedral Zn 0.3 Cd 0.7 S@NiCo-MMO composite photocatalyst. In hydrogen production performance test, the optimized Zn 0.3 Cd 0.7 S@NiCo-MMO exhibited excellent performance (8177.5 μmol·g−1·h−1) and demonstrated good cycling stability. The hollow dodecahedral structure of the Zn 0.3 Cd 0.7 S@NiCo-MMO enhanced the light trapping ability and provided large surface area. The p-n heterojunction formed within Zn 0.3 Cd 0.7 S@NiCo-MMO accelerated carrier separation and transfer, effectively inhibited the recombination of photogenerated electrons and holes, and significantly improved the hydrogen production activity. [ABSTRACT FROM AUTHOR]

The synergistic effect of internal electric field and energy band bending formed by NiFe 2 O 4 /ZnIn 2 S 4 p-n heterojunction significantly inhibits carrier recombination and thus improves the photocatalytic efficiency. [Display omitted] • A p-n heterojunction NiFe 2 O 4 /ZnIn 2 S 4 with magnetic recycle was synthesized. • 2 %-NiFe 2 O 4 /ZnIn 2 S 4 exhibits best TC degradation with 90.2 % degradation rate and 52.7 % TOC removal. • DFT confirmed generation of a built-in electric field, promoting carriers separation. • Superoxide radicals (O 2 −) and holes (h+) are the main active species. • Possible photocatalytic reaction pathways of tetracycline were analyzed by HPLC-MS. • Bioconcentration factor and developmental toxicity values was assessed. The persistent release of tetracycline into the environment significantly endangers both ecosystems and human health. Zinc indium sulfide (ZnIn 2 S 4) capable to degrade tetracycline pollutants under visible light irradiation has attracted extensive attentions and great effort has been devoted to augment its catalytic efficacy. In this work, we synthesized a p-n heterojunction, NiFe 2 O 4 /ZnIn 2 S 4 , to enhance the carrier migration rate and explained the intrinsic mechanism by density functional theory. When the heterojunction was formed, carriers traversed from the n -type NiFe 2 O 4 to the p-type ZnIn 2 S 4 , instigating the emergence of a built-in electric field to facilitate the separation of carriers. 2 %-NiFe 2 O 4 /ZnIn 2 S 4 exhibited excellent photocatalytic efficiency in tetracycline (TC) degradation and total organic carbon (TOC) removal. Compared to pure ZnIn 2 S 4 and NiFe 2 O 4 , the TC degradation rates of 2 %-NiFe 2 O 4 /ZnIn 2 S 4 were 2.0 times and 16.9 times higher, respectively. Additionally, 2 %-NiFe 2 O 4 /ZnIn 2 S 4 had a saturation magnetization intensity of 3.05 emu/g, allowing for rapid recovery of the catalyst under a magnetic field. Superoxide radicals (O 2 −) and holes (h+) were the primary active species driving the degradation process. Furthermore, potential reaction pathways of tetracycline in this photocatalytic process were determined and bioconcentration factor and developmental toxicity of the intermediate products were accessed. This work held great potentials for wastewater treatment and provided a pathway for the development of magnetic recyclable photocatalysts. [ABSTRACT FROM AUTHOR]

Highly sensitive uncooled mid-wave infrared (MWIR) photodetectors have a very wide range of applications ranging from the sensor and image to communications. Traditional MWIR detection semiconductors require liquid nitrogen cooling to depress dark current, which impeded the wide applications of devices. Here, we report a metal electrode-enhanced double parallel BP/InSe/BP van der Waals heterostructure uncooled MWIR photodetector. The device exhibits ultrahigh light on/off ratio of 108 and a very low dark current of 0.16 pA. The competitive performance includes high photoresponsivity (R) of 27.8 A W−1, excellent specific detectivity (D*) of 3.8 × 1012 cm Hz1/2 W−1, very low noise equivalent power (NEP) of 3.7 × 10−16 W Hz−1/2, and fast response speed of τr = 3.5 μs and τd = 2.4 μs in the visible range. Notably, in the MWIR range, the light on/off ratio of ∼104, NEP of 3.0 × 10−13 W Hz−1/2, and D* of 4.8 × 109 cm Hz1/2 W−1 was realized. The work sheds light on developing a high-performance uncooled MWIR photodetector by designed band alignment. [ABSTRACT FROM AUTHOR]

A mechanochemical approach through ball milling (BM) to produce NiO clusters supported on TiO 2 has been successfully applied, resulting in a NiO/TiO 2 p-n heterojunction as an efficient and sunlight-sensitive photocatalyst. Besides, the synergistic interaction between NiO and TiO 2 (P90) enhances charge separation, ultimately boosting the H 2 photoproduction. Notably, the material obtained by BM, denoted as NiO/P90-BM achieved an H 2 evolution rate that was over 12 times higher than that of Neat P90 (8.85 mmol h−1 g−1 vs. 0.73 mmol h−1 g−1). The predominance of the high-spin configuration for Ni2+ in NiO was ascribed as one of the main reasons for such performance. Additionally, photoelectrochemical measurements revealed that NiO addition was beneficial for the photoelectrochemical properties. The NiO/P90-BM exhibited the lowest charge transfer resistance, the highest photocurrent signal, and the highest electronic density. Furthermore, the achieved H 2 evolution rate is on par with that of materials produced using noble metals and energy-intensive approaches. Noticeably, cycling, long-term, and aging tests have shown that the reported photocatalyst is efficient after several cycles, prolonged use, and after long periods of storage. [Display omitted] • One-step ball milling process led to a NiO/TiO 2 p-n heterojunction. • The addition of NiO boosted sunlight absorption. • This noble metal-free photocatalyst exhibited an outstanding H 2 evolution rate. • High-spin of Ni2+ in NiO was crucial for such outstanding performance. • NiO/P90-BM performs comparably to noble metal-based and energy-intensive materials. [ABSTRACT FROM AUTHOR]

The detection of trimethylamine (TMA) is critically important due to its toxic and flammable nature, which poses significant risks to human health and the environment. However, achieving high response, rapid kinetics, selectivity, and low operating temperatures in TMA sensing remains challenging. In this study, WS2/WO3 nanohybrids with flower-like hierarchical structures were synthesized via an in situ sulfurization process, utilizing varying amounts of thioacetamide to control the sulfurization state of WO3. These novel hierarchical WS2/WO3 nanohybrids exhibit remarkable selectivity towards TMA, as well as rapid response and recovery characteristics. Specially, the optimal WS2/WO3 sensor, composed of 5% WS2/WO3 nanohybrids, demonstrates exceptional TMA sensing performance, including a high response (19.45 at 10 ppm), good repeatability, reliable long-term stability, and a low theoretical detection limit (15.96 ppb). The superior sensing capabilities of the WS2/WO3 nanohybrids are attributed to the formation of p-n heterojunctions at the interface, the unique hierarchical structures, and the catalytic activity of WS2. Overall, this work provides a straightforward and versatile approach for synthesizing multifunctional nanomaterials by combining metal oxide micro-flowers with transition metal dichalcogenide nanoflakes for applications in monitoring TMA in complex environments. [ABSTRACT FROM AUTHOR]

Conventional metal sulfide (SnS2) gas-sensitive sensing materials still have insufficient surface area and slow response/recovery times. To increase its gas-sensing performance, MoS2 nanoflower was produced hydrothermally and mechanically combined with SnS2 nanoplate. Extensive characterization results show that MoS2 was effectively integrated into SnS2. Four different concentrations of SnS2–MoS2 composites were evaluated for their NO2 gas sensitization capabilities. Among them, SnS2–15% MoS2 at 170 °C demonstrated the greatest response values to NO2, 7.3 for 1 ppm NO2, which is about three times greater than the SnS2 sensor at 170 °C (2.58). The creation of pn junctions following compositing with SnS2 was determined to be the primary reason for the composite's faster recovery time, while the heterojunction allowed for the rapid separation of hole–electron pairs. Because the MoS2 surface has multiple vacancy defects, the adsorption energy of these vacancies is significantly higher than that of other places, resulting in increased NO2 adsorption. Furthermore, MoS2 can serve as active adsorption sites for SnS2 micrometer sheets during gas sensing. This study may help to build new NO2 gas sensors. [ABSTRACT FROM AUTHOR]

This paper presents a hydrogen sensor made of WSe 2 modified monocrystalline SnSe 2 nanolayer. The hydrogen sensitive property of tungsten diselenide (WSe 2) and tin diselenide (SnSe 2) was found by hydrothermal adjustment of the molar ratio. The samples were characterized for their crystal structure, microstructure, morphology, and elemental composition, and the morphology and heterojunction formation of the nanocomposites were confirmed. When the optimal molar ratio is 1:1 and the optimal working temperature is 270 °C, the WSe 2 /SnSe 2 sensor have good sensing properties for hydrogen, and the sensitivity for 100 ppm hydrogen is about 7.27. Finally, the experiment proves that WSe 2 /SnSe 2 gas sensor has a unique selection of hydrogen and has a wide application prospect in hydrogen detection in the future. The gas sensing mechanism of the hydrogen sensor is discussed based on its material structure. • A hydrogen sensor with WSe 2 modified monocrystalline SnSe 2 was proposed. • The sensor has the best response to hydrogen at 270 °C. • The enhanced sensing mechanism with p-n heterojunction is discussed. • Hydrogen sensor has fast response and long-term stability. [ABSTRACT FROM AUTHOR]

Mining industries have long relied on cyanidation as the primary method for gold extraction, but this process generates thiocyanates as a problematic byproduct, posing challenges for wastewater treatment and recycling. The stability of thiocyanates makes their reduction or elimination in mining wastewater difficult. In this study, a p-n heterojunction of ZnO and BiOI was created and evaluated for its ability to photodegrade thiocyanate ions under simulated solar conditions. Various analytical techniques revealed a highly porous structure with a sponge-like morphology and agglomeration in the synthesized heterojunction. The compound exhibited crystalline patterns without impurity peaks, a slight red shift in absorbance, and Type IV isotherm adsorption. The synthesized heterostructure achieved the complete destruction of thiocyanate ions in less than 30 min. The investigation of different process parameters indicated that the destruction of the contaminant by the heterostructure was influenced by the initial thiocyanate concentration, which decreased as the thiocyanate concentration increased. The peak photodestruction reaction was observed at pH 7. By applying a pseudo-first-order kinetic model, it was found that increasing the catalyst mass to 15 mg raised the rate constant from 0.188 to 0.420 min−1, while increasing the pH to 10 led to a 3.5-fold reduction. The strong correlation between the observed data and the predicted values of the pseudo-first-order kinetic model was indicated by the observed (R2) values. The findings of this study hold potential significance for mining industries, as it offers a potential solution for eliminating cyanide and thiocyanates from mining wastewater. The elimination of thiocyanate generation in the cyanidation process is crucial for mining companies, making this study valuable for the industry. [ABSTRACT FROM AUTHOR]

Abstract:In this paper, porous n-GaN thin films with a pore density of 1. 51 x 1010 Cm-2 and an average pore size of 38 nm were initially prepared by UV-assisted electrochemical etching (UV-EC). Subsequently, a series of ZnxCu1- xS composite films, with x values of 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0, were deposited on the porous n-GaN films by water bath method. The bandgaps of the porous n-GaN/ZnxCu1-xS heterojunctions varied in the range from 2. 34 eV to 3. 51 eV. Hall test results demonstrate that when x values is less than 1, the ZnxCu1-xS composite films exhibit p-type semiconductor properties. Furthermore, increasing the proportion of CuS leads to an improvement in the conductivity of the composite films. Additionally, XPS results confirm that both Cu and Zn possess a + 2 valence within the composite films. When ZnxCu1-xS forms a heterojunction with porous n-GaN, the energy band structures of both materials interact to create a built-in electric field. This field facilitates the efficient separation of photogenerated electron-hole pairs. Finally, p-n heterojunctions UV detectors were constructed based on these heterostructures. The I-V curve results indicate that these detectors exhibit good rectification characteristics. Notably, the n-GaN/p-Zn0.4Cu0.6 S detector demonstrates optimal performance. In the dark state, I+3V/I-3V is approximately 1. 78 x 105. Under a bias voltage of - 3 V and an optical power density of 432 μW/cm² (ultraviolet light at 365 nm), this detector's photo-to-dark current ratio exceeds 103, the rise/fall time is 0.09/39.8 ms, responsivity(R) reaches 0. 352 A/W, the external quantum efficiency (EQE) stands at 119.6%, and detectivity(D*) is 3. 21 x 1012 Jones. The I-t curve results indicate that the porous n-GaN/p-ZnxCu1-xS heterojunctions UV detector possesses reproducible performance during the consecutive on-off optical cycling process with reproducible photocurrent response. This study offers valuable theoretical insights and a comprehensive understanding of the physical properties and performance characteristics of these novel heterostructures UV detectors. [ABSTRACT FROM AUTHOR]

[Display omitted] The commercial application of lithium-sulfur batteries is primarily impeded by the constant shuttling of soluble polysulfides and sluggish redox kinetics. Nowadays, the discovery of the heterojunction, which combines materials with diverse properties, offers a new perspective for overcoming these obstacles. Herein, a functional coating separator for the lithium-sulfur battery is designed using a MnO 2 -ZnS p-n heterojunction with a spontaneous built-in electric field (BIEF). The MnO 2 nanowire provides suitable adsorption capacity for polysulfides, while the abundant reactive sites brought by ZnS ensure efficient conversion. Moreover, the BIEF significantly facilitates the migration of electrons and polysulfides at the MnO 2 -ZnS interface, enabling a smooth "adsorption-diffusion-conversion" reaction mechanism. By serving as both the adsorption module and catalytic sites, this BIEF allows batteries utilizing separators modified with MnO 2 -ZnS heterojunction to achieve an impressive initial capacity of 1511.1 mAh g−1 at 0.1C and maintain a capacity decay rate of merely 0.048% per cycle at 2.0C after 1000 cycles. Even when increasing sulfur loading to 9.4 mg cm−2 in lean electrolyte (5.4 μL mg−1), the battery still exhibits an ultrahigh areal capacity of 6.0 mAh cm−2 after 100 cycles. [ABSTRACT FROM AUTHOR]

This study aimed to develop a highly sensitive, selective, and humidity-insensitive acetone sensor using ZnS mixed NiO heterostructure. An analysis was performed to understand the enhanced sensing behavior of pristine NiO mixed with ZnS. The p-n heterojunction between ZnS and NiO forms a heterojunction barrier at the interface of the two semiconducting materials. The heterojunction enhanced the number of oxygen vacancies and adsorbed oxygen atoms in the ZnS-NiO composite, which improved its gas-sensing capabilities. Different molar percentages of ZnS relative to nickel were added to understand the effect of ZnS doping on Nickel oxide. The products were characterized using X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), X-ray Photoelectron Spectroscopy (XPS), and UV-visible Spectroscopy to determine the properties of the materials. The sensor exhibited a response of 35% response to 50 ppm acetone at an operating temperature of 225 °C. This response was higher than that of pristine NiO reported in our previous work. This enhanced behavior can be attributed to crystal lattice distortion caused by the mixing of ZnS with NiO. This study highlights the potential of ZnS mixed NiO heterostructures for developing highly sensitive and selective sensors for breath analyzer applications. [ABSTRACT FROM AUTHOR]

The built‐in field (Ebi) is a key factor for the dynamic of carrier transport in the heterojunction interface, thus determining the photovoltaic performance of the solar cell, such as Cu2ZnSn(S,Se)4 (CZTSSe) cell. It is critical to improve the carriers' transport across the pn heterojunction for the fabrication of highly efficient solar cells. In this work, the large electric field of ferroelectric BaTiO3 nanoparticles (BTO NPs) is used to tailor the carrier transport in the CZTSSe solar cells by embedding BTO NPs into the interface of CZTSSe/CdS heterojunction. It is very surprising that a polarization electric field (EP) with the same direction of Ebi synergically enhances carrier transport greatly and increases the PCE by 20.6%. Further study on the mechanism discloses that BTO NPs reduce the work function of CZTSSe and CdS and form interfacial dipoles at their interface, which is conducive to the photogenerated electrons to be collected by the electron transport layer. This strategy also works well on other thin film solar cells and gives a new aspect of strengthening the carrier transport between p–n heterojunction. [ABSTRACT FROM AUTHOR]

High sensitivity and selectivity and short response and recovery times are important for practical conductive polymer gas sensors. However, poor stability, poor selectivity, and long response times significantly limit the applicability of single-phase conducting polymers, such as polypyrrole (PPy). In this study, PPy/MoS2 composite films were prepared via chemical polymerization and mechanical blending, and flexible thin-film resistive NO2 sensors consisting of copper heating, fluorene polyester insulating, and PPy/MoS2 sensing layers with a silver fork finger electrode were fabricated on a flexible polyimide substrate using a flexible electronic printer. The PPy/MoS2 composite films were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy. A home-built gas sensing test platform was built to determine the resistance changes in the composite thin-film sensor with temperature and gas concentration. The PPy/MoS2 sensor exhibited better sensitivity, selectivity, and stability than a pure PPy sensor. Its response to 50 ppm NO2 was 38% at 150 °C, i.e., 26% higher than that of the pure PPy sensor, and its selectivity and stability were also higher. The greater sensitivity was attributed to p–n heterojunction formation after MoS2 doping and more gas adsorption sites. Thus, PPy/MoS2 composite film sensors have good application prospects. [ABSTRACT FROM AUTHOR]

With the abuse of antibiotics, its pollution poses an increasing threat to the environment and human health. Effective degradation of organic pollutants in water bodies is urgent. Compared to traditional treatment methods, advanced oxidation processes that have developed rapidly in recent years are more environmentally friendly, efficient and applicable to a wider range of organic compounds. FeWO4 was used in this study as the iron-based semiconductor material to modify and optimize the material design. Fe3O4/FeWO4 composites were prepared by a two-step hydrothermal method. The crystal structure, surface morphology, electrochemical properties and separability of the composite semiconductor were analyzed by XRD, XPS, UV-vis, SEM, EDS and Mott-Schottky. The results showed that, when the initial contaminant concentration was 30 mg/L, the initial solution pH was 4, the dosage of the catalyst was 25 mg and the dosage of hydrogen peroxide was 30 μL, the degradation efficiency of tetracycline hydrochloride (TCH) could reach 91% within 60 min, which was significantly improved compared to the performance of the single semiconductors Fe3O4 and FeWO4. In addition, the catalyst prepared in this experiment can be easily recovered by magnetic separation technology in practical application, which will not affect the turbidity of water while reducing the cost of catalyst separation and recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] In this research, a self-healing nano-coating with excellent photo-thermal response to near-infrared (NIR) laser is prepared. This coating incorporates silver sulfide anchored bismuth molybdate (Ag 2 S@Bi 2 MoO 6) into a shape memory epoxy resin to achieve for a good photo-thermal conversion capability. The Ag 2 S@Bi 2 MoO 6 p-n heterojunction could photo-generate more electron-holes pairs under the NIR laser irradiation. Also, it shows a wider absorption range of visible light, leading to effectively absorb the light energy, generate enough heat to induce the shape memory recovery in the coating, and seal the scratch. The results indicate that the temperature of EP-1 % Ag 2 S@Bi 2 MoO 6 coating has reached about 88 °C, while good self-healing and anti-corrosion properties with a self-healing rate of 88.41 % have been achieved. Furthermore, calculations based on Density Functional Theory and Finite Element Method pointed out that the formation of p-n heterojunction effectively has enhanced the photo-thermal effect. This research opens a new way for developing self-healing coatings with an ultra-fast response time and high self-healing efficiency. [ABSTRACT FROM AUTHOR]

Gas sensors for ammonia (NH3) play a crucial role in the maintenance of air quality, preservation of the atmosphere, and evaluation of human health. However, the endeavor to attain a high level of sensitivity in detecting NH3 under ambient conditions remains a challenging task. In this work, poly(3‐hexylthiophene)s and titanium dioxide (P3HT‐TiO2) heterostructure NH3 gas‐sensitive material was prepared, and by drop‐casting the material onto a substrate with Au interdigital electrodes, a sensor for high‐response detection of NH3 at room temperature was constructed. The designed gas sensor exhibited a high response signal of 114.61 % toward 15 ppm NH3 at room temperature (25 °C) with good reproducibility, strong long‐term stability, and excellent selectivity. Moreover, by analyzing the response law of the sensor under different humidity conditions, it has been noted that both excessively high and excessively low levels of humidity adversely affect the sensor's response. The remarkable increase in NH3 sensing properties is attributed to the synergistic enhancement effect of P−N heterojunction formed between P3HT and TiO2. This NH3 gas sensor exhibits tremendous potential for use due to its straightforward structure and outstanding ammonia sensing performance. [ABSTRACT FROM AUTHOR]

Printing and dyeing wastewater, that is discharged after textile printing and dyeing processing, can cause irreversible damage to the aquatic ecosystem and harm the health of human beings. Till now, completely and readily removing dye molecules from industrial wastewater using a single catalyst rather than the combination of several materials remains a significant challenge. Herein, in situ preparation of carbon nanotube membranes (N‐CNTM and N‐TiO2‐CNTM) are reported that are doped using N with/without TiO2, respectively. These membranes can simultaneously function as an adsorber, a photo‐catalyst, and an electrocatalyst to efficiently remove dye pollutes from industrial waste water. Further researches reveal that the formation of p‐n type heterojunction inside of the N‐CNTM and N‐TiO2‐CNTM, can improve the hole separation and charge storage abilities, resulting in the efficient removal of dyes in the industrial waste water. This work provides a promising approach for the preparation of functionalized carbon nanotubes derived from waste biomass for the treatment of industrial water, reflecting the concept of treating waste with waste. [ABSTRACT FROM AUTHOR]

Advancing supercapacitor system performance hinges on the innovation of novel electrode materials seamlessly integrated within distinct architectures. Herein, we introduce a direct approach for crafting nanorod arrays featuring crystalline/amorphous CuO/MnO2−x. This reconfigured heterostructure results in an elevated content of electrochemically active MnO2. The nanorod arrays serve as efficient capacitive anodes and are easily prepared via low-potential electrochemical activation. The resulting structure spontaneously forms a p–n heterojunction, developing a built-in electric field that dramatically facilitates the charge transport process. The intrinsic electric field, in conjunction with the crystalline/amorphous architecture, enables a large capacitance of 1.0 F·cm−2 at 1.0 mA·cm−2, an ultrahigh rate capability of approximately 85.4% at 15 mA·cm−2, and stable cycling performance with 92.4% retention after 10,000 cycles. Theoretical calculations reveal that the presence of heterojunctions allows for the optimization of the electronic structure of this composite, leading to improved conductivity and optimized OH− adsorption energy. This work provides new insights into the rational design of heterogeneous nanostructures, which hold great potential in energy storage applications. [ABSTRACT FROM AUTHOR]

W-doped ZnO thin films deposited on Si substrates with (100) orientation by sol–gel spin coating method at temperature 500 °C. W/Zn atomic ratio varies from 0% to 4%. Then, the UV detection performance analysis of p–n heterojunction UV photodetectors based on W-doped ZnO/Si is analyzed. The current–voltage curves of W-doped ZnO/Si are investigated in dark and exhibit diode-like rectifying behavior. Among doped ZnO/Si, sample with atomic ratio of W/Zn = 2% is the best candidate to study photodetector characteristics in UV range. The resulting device exhibits a rectification ratio RR of 5587 at ±5 V, a higher responsivity of 3.84 A W−1 and a photosensitivity value of 34 at 365 nm under 0.5 mW cm−2. The experimental findings reveal that the UV detection performance of the heterojunction-based photodetectors strongly dependent on the properties of metal oxide layer. The main goal of this work is to investigate the effect of W doping on the performance of ZnO/Si based photodetectors. Based on our results, it is observed that 2 at% of W dopant is the optimum amount of doping for high performance photodetector of ZnO:W/Si heterojunction thanks to the suppressed recombination ratio and enhanced carrier separation properties in the depletion zone. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen (H2) evolution can effectively solve the global energy problem, in which the key factor is the synthesis of efficient photocatalytic materials. In this study, we successfully synthesized a novel photocatalyst, BiWCo/CuS/PGCN, by functionalizing porous graphitic carbon nitride (PGCN) with sandwich-type polyoxometalate Na3.5Co4[Bi2Co2W19.75O70(H2O)6]·39.5H2O (BiWCo) and introducing copper sulfide (CuS) nanoparticles as a cocatalyst. This approach was aimed at enhancing the built inner electric field between interfaces, resulting in a significant improvement in photocatalytic H2 evolution performance. This research adopts a step-by-step method to synthesize BiWCo/CuS/PGCN composites with p–n heterojunctions, which has high visible light absorption and a synergistic effect of multiple elements. PGCN with a high specific surface area contributes to the uniform distribution of active sites. In addition, the nano-CuS cocatalyst provides abundant active sites and more electron transfer pathways for photocatalysis. Therefore, the H2 production efficiency of BiWCo/CuS/PGCN is 6.3 times that of PGCN, 4.5 times that of BiWCo and 2.5 times that of BiWCo/PGCN under visible light. The H2 production rate of BiWCo/CuS/PGCN reaches 3477.58 μmol g−1 h−1. At the same time, the ternary photocatalyst shows high stability after 30 hours and 5 cycles. This work demonstrates that BiWCo/CuS/PGCN has good application prospects in H2 evolution, and provides a new strategy for the design of efficient ternary photocatalytic materials. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO 3 RR) provides a promising method for ammonia (NH 3) producing. It is urgent to develop efficient catalysts with improved NO 3 RR performance. In this paper, Cu 3 P@Co(OH) 2 /CF heterostructure catalyst is constructed by electrodeposition of cobalt hydroxide (Co(OH) 2) nanosheet on the surface of copper phosphide (Cu 3 P) nanorod, and used as a self-supporting cathode for electrocatalytic reduction of nitrate to ammonia. The NH 3 yield reaches 0.19 mmol h−1 cm−2 at a potential of −0.17 V vs. RHE, and the faraday efficiency (FE) is 86.7 %. The study manifests that the built-in electric field generated at the p-n heterojunction interface optimizes the electron migration kinetics, and promotes the adsorption of nitrate and the convention of intermediate product NO 2 − into ammonia. As a consequence, the selectivity of NH3 is improved. The Zn-nitrate battery is assembled with the designed catalyst as the cathode, to reach a peak power density of 5.16 mW cm−2. The prepared catalyst realizes three effective functions: power output, ammonia synthesis, and nitrate pollutants treatment. [Display omitted] • Cu 3 P@Co(OH) 2 /CF heterostructure material was synthesized by low temperature phosphating and electrodeposition methods. • The built-in electric field at the p-n heterojunction promotes the convention of intermediate NO 2 − into ammonia. • Cu 3 P@Co(OH) 2 /CF effectively promotes the *H pathway for NO 3 − reduction to NH 3. • Zn-nitrate battery was built with Cu 3 P@Co(OH) 2 /CF cathode to realize multi-functional applications. [ABSTRACT FROM AUTHOR]

In this work, Co3O4/Bi2MoO6 p‐n‐type heterojunctions were successfully fabricated via a hydrothermal method combined with in‐situ deposition. The as‐prepared samples were systematically characterized by means of SEM, TEM, XPS, XRD, etc. Through the synergistic effect of PMS (peroxosulfate monosalt), the obtained composite CB‐2 has a superior degradation performance of enrofloxacin under visible light irradiation, and the degradation rate of enrofloxacin reaches 87.84 % within 30 min. The reaction process of enrofloxacin degradation was analyzed by 3D EEM (exception emission matrix spectrum) and LC–MS (liquid phase mass spectrometry). The influence of the reaction system on EFA degradation efficiency without PMS synergy and light was studied. The kind of free radical was determined from the outcome of the EPR and free radical capture experiment. Benefiting from the construction of the p‐n heterojunction system and the activation of the PMS, the photogenerated carriers of the Co3O4/Bi2MoO6 composite can be fully separated and transferred to produce active species with higher oxidative properties. Based on this, the photocatalytic mechanism of Co3O4/Bi2MoO6/PMS was explored. [ABSTRACT FROM AUTHOR]

[Display omitted] • Construction of octagonal 2D nanoplates with large specific surface area exposes more active sites and accelerates mass transfer for improved OER performance. • The formation of p-n heterojunction between FeP and CoP induces the generation of embedded electric field, optimizes the electronic structure, and improves the intrinsic activity of OER. • DFT calculations confirm the existence of charge transfer at the heterojunction interface and effectively optimize the Gibbs free energy of the OER. Surface reconstruction of electrocatalysts is an effective strategy to modulate the space charge distribution to enhance the electrocatalytic activity. The p-n heterostructured FeP/CoP-2D octagonal nanoplates were successfully constructed by cation-exchange method. The space charge effect caused by the p-n heterojunction accelerated the electron transfer, optimized the electronic structure, and improved the activity of the active sites during the oxygen evolution reaction process. As a result, FeP/CoP-2D required only 247 mV overpotential to achieve a current density of 10 mA cm−2 with a Tafel slope as low as 68 mV dec-1. Density-functional theory calculations confirmed that the construction of p-n heterojunctions can enhance the adsorption of *OH in the active centers and optimize the Gibbs free energy of the OER reaction. This study provides an effective and feasible strategy for constructing p-n heterojunctions to modulate the space charge state for optimizing the OER performance of electrocatalysts. [ABSTRACT FROM AUTHOR]

Highly sensitive p -MoS 2 /n-MoO 3 nanocomposite-based chemo-resistive gas sensors are synthesized by varying the reducing agents using hydrothermal synthesis followed by thermal annealing in an Ar environment for NH 3 and NO 2 detection at 50 °C. Structural characterizations confirmed the existence of MoS 2 nanoflakes and MoO 3 nanoplatelets and the appearance of abundant oxygen adsorption sites and sulfur vacancies in the nanocomposites. The MoS 2 :MoO 3 -based sensor (without any reducing agent) showed preferential detection of NH 3 with 52% sensor response for 5 ppm gas concentration having response/recovery times of 28 s/97 s with n-type sensing behavior dominated by MoO 3 charge carriers. On the contrary, NO 2 gas attracts electrons from the MoS 2 surface, exhibiting p-type sensing behavior with a sensor response of 42 % consisting of response/recovery times of 56 s/116 s with 5 ppm concentration at 50 °C. More interestingly, different adsorption sites and conductive channels play a huge role in the MoS 2 :MoO 3 nanocomposite for exhibiting opposite sensing behaviours upon exposure to NH 3 and NO 2 gases. Enhanced sensitivity is dedicated to synergistic effects appearing due to the construction of p-n heterojunction to strengthen carrier transport by enhancing the sensor response. The present work provides a unique methodology for constructing MoS 2 :MoO 3 -based sensors and the effect of reducing agents on various MoS 2 :MoO 3 -based sensors. Moreover, our study recommends the plausible use of the MoS 2 :MoO 3 composite-based heterojunctions to provide a constructive strategy for improving the performance of gas sensors. [ABSTRACT FROM AUTHOR]

Photocatalytic technology, as one of the most promising environmental remediation tools, has a wide range of applications in the field of removing antibiotic-based pollutants from wastewater. Therefore, to obtain efficient green and inexpensive photocatalysts, a p–n type Bi2MoO6/CuS composite photocatalyst modified by lignin carbon quantum dots (CQDs) was successfully prepared by solvothermal in situ co-precipitation in this study. It was used to achieve efficient photocatalytic degradation of tetracyclic hydrochloride antibiotics (TCH). The composites were systematically characterized by XRD, FTIR, XPS, SEM, TEM, EIS, nitrogen adsorption–desorption test, and UV–Vis DRS regarding crystal structure, microscopic morphology, and photoelectric properties. The results showed that the prepared samples had good crystallinity and high purity. The photocatalytic degradation experiments further demonstrated that the Bi2MoO6/CuS composites modified by CQDs exhibited excellent photocatalytic activity compared to Bi2MoO6 and CuS monomers wherein CQDs@Bi2MoO6/CuS 2 was the most effective, with a TCH removal of 96.98% and a degradation rate constant (K) of 0.04405 min−1 after 60 min of light exposure. The TCH removal could be maintained at 78.25% after four cycles. The ESR and LC–MS experiments demonstrated that h+ and ·O2− were the main active substances for photocatalytic degradation of TCH. This work provides an efficient catalyst for TCH removal and offers new ideas for applying p–n heterojunction composites in photocatalysis. [ABSTRACT FROM AUTHOR]

Photocatalytic conversion of renewable biomass‐derived aldehydes into high‐valued chemicals is a promising path to meet the growing demand for clean energy and chemical resources. However, the approach still faces challenges, such as limited reaction types and low utilization rates due to the complex functional groups and involved polytropic reaction. In the present work, we developed a catalyst of Pt nanoparticles (Pt NPs) supported on a NiO–In2O3 bimetallic oxide (denoted as Pt/NiInOx) for photocatalytic hydrogenation of furfural (FAL) to furfural alcohol (FOL). Owing to the excellent band structure and efficient internal charge transfer on the p–n heterojunction in the catalyst, the highest 99.9% yield to FOL was obtained over the Pt/NiInOx under a light‐emitting diode (LED) light at low temperatures as 273 K. The combination of ·H dissociated from H2 and oxygen vacancy work synergically to adsorb, activate, and converse C=O to the C–O group. The photocatalytic system presents a highly efficient approach for the rapid hydrogenation of biomass‐based aldehydes under a low LED light radiation intensity at a low temperature. The work is expected to serve as an important reference in constructing bimetallic oxide‐supported active metals, enabling efficient separation of photogenerated electrons and holes, and offering oxygen vacancies in various photocatalytic reactions. [ABSTRACT FROM AUTHOR]

In this research, the photocatalytic degradation of methylene blue was investigated using synthesized PdO/CoS nanocomposite under visible light irradiation. The structural and morphological properties were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, Mott–Schottky analysis, and transmission electron microscopy (TEM). The Mott–Schottky analysis confirmed the formation of a p-n heterojunction, and the flat band potential values for the n-type and p-type semiconductors were found to be − 1 and 1.3, respectively. The bandgap of the composite was determined to be 3 eV using Diffuse Reflectance Spectroscopy (DRS). When 0.1 g of the synthesized composite was used for 90 min, it successfully degraded 91% of methylene blue with an initial concentration of 10 ppm. In the Design of Experiments (DOE) approach, the optimum conditions for this research were found to be a catalyst mass of 0.06 g, an initial dye concentration of 8 ppm, and 2% palladium doping at pH 10, resulting in a 92.38% degradation efficiency in 110 min. To model the degradation of methylene blue using the synthesized composite, the Fritz–Schlunder and Koble–Corrigan models achieved the highest correlation coefficients (0.995 and 0.992, respectively) and the lowest error functions (0.024, 0.0008) and (0.032, 0.002), respectively. Additionally, the Langmuir–Hinshelwood and Intra-particle diffusion control kinetic models showed the highest correlation coefficient (98%). In summary, the study demonstrated that the PdO/CoS composite exhibited excellent photocatalytic activity for methylene blue degradation, and the optimized conditions resulted in high degradation efficiency. The proposed kinetic models provided valuable insights into the degradation mechanism of methylene blue using the synthesized composite. [ABSTRACT FROM AUTHOR]

Using a p-n heterojunction is one of the efficient methods to increase charge transfer in photocatalysis applications. So, herein, p-type UiO-66 (NH2) and n-type CuFe2O4 (CFO) are used to form an effective p-n heterojunction. Due to their poor charge separation in their pristine form, both UiO-66 (NH2) and CFO materials cannot produce hydrogen; however, the composite p-n heterojunction formed between these materials makes fast charge separation and so hydrogen is efficiently produced. The optimized catalyst UCFO 25% produces a maximum of 62.5 µmol/g/h hydrogen in an aqueous methanol solution. The formation of a p-n heterojunction is confirmed by Mott–Schottky analysis and optical properties, crystallinity and the local atomic environment of the material was analyzed by various analytical tools like UV-Vis spectroscopy, XRD, and XANES. [ABSTRACT FROM AUTHOR]