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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]

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]

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 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]

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]

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]

[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]

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]

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]

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]

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]

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]

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]

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]

[Display omitted] • CoWO 4 /Zn 0.3 Cd 0.7 S heterojunction was prepared by self-assembly method. • Zn vacancies are the capture centers of photogenerated holes. • p-n heterojunction improves the transfer of photogenerated charge carriers. • Photocatalytic H 2 evolution is promoted by 4-Chlorobenzyl alcohol oxidation. To enhance the efficiency of photocatalytic H 2 evolution, numerous methods are employed by increasing the utilization of photogenerated charge carriers (PCCs), including catalyst design, defect regulation, and selection of suitable H+ resources. Using self-assembly method, CoWO 4 /Zn x Cd 1−x S with p–n heterojunction was synthesized. Although CoWO 4 (CW) cannot produce H 2 under visible light irradiation, it can provide photogenerated electrons (e−) to Zn 0.3 Cd 0.7 S (ZCS), and largely increase the photocatalytic activity of ZCS. The optimal CW/ZCS composite can reach 15.58 mmol·g−1·h−1, which is 45.8 and 24.3 times higher than the values of the pure CdS and ZCS, respectively. The largely enhanced photocatalytic H 2 production is attributed to the Zn vacancies (V Zn), p–n heterojunction, and p-chlorobenzyl alcohol (Cl–PhCH 2 OH) as the H+ source of H 2 production. V Zn on the ZCS surface as the capture center of photogenerated holes (h+), can regulate the carrier distribution, which results in more photogenerated e− and less generated h+. The combination of p–n heterojunction and V Zn can enhance the separation and transfer efficiency of PCCs, and effectively inhibit the recombination of charge carriers. To further improve the utilization rate of PCCs, the photocatalytic H 2 evolution is proceeded by Cl–PhCH 2 OH oxidation in N , N -dimethylformamide solution, with 4-chlorobenzaldehyde (Cl–PhCHO) generated. The separated photogenerated e− and h+ both participated in the redox reaction of H+ reduction and Cl–PhCH 2 OH oxidation, considering that the amount of H 2 and Cl–PhCHO products are close to 1:1. This work not only facilitates the separation and transfer of PCCs, but also provides directions for the design of efficient photocatalysts and H 2 evolution in the organic phase. [ABSTRACT FROM AUTHOR]

Herein, the SrTiO 3 -TiO 2 -CaTiO 3 /Cu 2 O quaternary composite has been designed and prepared via one-step hydrothermal process followed by a NaBH 4 reduction treatment. By comparing the H 2 production rate (HPR) of Sr-Ti-Ca/Cu samples prepared by different Cu sources, it is found that Sr-Ti-Ca/Cu has the best H 2 production performance when CuCl 2 is as Cu source. As expected, the highest HPR of Sr-Ti-Ca/Cu sample is up to 5.088 mmol g−1 h−1, which is 195.7 times as higher as that of the Sr-Ti-Ca sample (0.026 mmol g−1 h−1) under the same conditions. Moreover, the HPR reached 0.692, 0.530 and 0.647 mmol g−1 h−1 in tap water, lake water and river water, indicating that the photocatalyst has high practicability in natural water sources. In addition, the experiment of the tap water composition effect on H 2 production performance shows that NO 3 − and SO 4 2− ions have great negative influence on the HPR. Compared with Sr-Ti-Ca, the light absorption of Sr-Ti-Ca/Cu extends over the entire visible region, the interface resistance decreases, and the photocurrent density increases. These results suggest that the well-designed dual p-n heterojunctions and dual type-II heterojunctions in Sr-Ti-Ca/Cu sample can enhance the light absorption in the ultraviolet region and realize the rapid separation and migration of photogenerated charge, thereby accelerating the production of H 2. This work shows the strong advantage and potential of non-precious metal efficient photocatalyst system for producing H 2 from deionized water and natural fresh water. The SrTiO 3 -TiO 2 -CaTiO 3 /Cu 2 O quaternary composite with dual p-n heterojunctions and dual type-II heterojunctions was successfully designed and prepared by a facile two-step synthesis process firstly, and it exhibited high hydrogen production rate in deionized water and natural fresh water. [Display omitted] • The multi-type heterojunctions can promote the separation of carriers. • Sr-Ti-Ca/Cu exhibited high H 2 production rate. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) is a significant alternative energy supply due to its outstanding and potentially useful properties, promoting sustainable development. Photocatalytic H 2 generation from H 2 O employing inexhaustible and naturally abundant solar power on semiconducting photocatalysts is a promising and sustainable approach. Yet, particle aggregation/agglomeration, insufficient solar-light absorbance capacity, and quick photo-excited charge carriers' recombination are the main deficiencies in most current photocatalytic systems. This investigation intends to fabricate mesoporous YVO 4 nanosheets through a facile hydrothermal process, employing polyvinyl alcohol polymer as a structural directing agent to prevent agglomeration. Moreover, for the first time, varied tiny contents of platinum oxide (PtO) ranging from 0.3 to 1.2 wt%, were decorated on YVO 4 , constructing p-n PtO-YVO 4 heterojunctions. The fabricated catalysts were characterized via advanced instruments and applied to H 2 production using visible light energy. It was found that the physicochemical characteristics of the designed catalysts revealed the influence of loading PtO on the surface, structure, light absorbance features, charge separation, and efficacy. The loading of 0.9 wt% PtO on YVO 4 has barely lowered the surface area (SA) from 187 to 176 m2/g. In contrast, the visible wavelength uptake is notably extended owing to the substantial energy bandgap narrowing from 3.40 to 2.11 eV. The visible-light-evolved hydrogen on 0.9 wt% PtO-YVO 4 amounted to 34.76 mmol g−1. Moreover, this novel sample demonstrated a 99.88% recycling capacity after five cycles. This efficacious photocatalytic H 2 generation is due to extensive light sensitivity and the rapid charge separation and migration between PtO and YVO 4 following the p-n heterojunction mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing effective heterojunction photocatalysts that efficiently separate charge carriers and improve light-harvesting capabilities is crucial in addressing energy and environmental issues. Herein, a unique nanocomposite photocatalyst is constructed by attaching CoMn 2 O 4 nanoparticles onto 2D CdS nanosheets for H 2 production and U(VI) reduction. The optimized 2% CoMn 2 O 4 /CdS nanocomposite showcases the highest photocatalytic H 2 production efficiency, 5.8 times higher than CdS nanosheets. Additionally, the U(VI) reduction rate constant of 2% CoMn 2 O 4 /CdS is 0.0192 min−1, approximately 1.9 folds over the pristine CdS (0.0101 min−1). The exceptional photocatalytic performance toward photocatalytic H 2 evolution and U(VI) reduction reactions directly result from the electronic integration between CoMn 2 O 4 /CdS p-n heterojunction, facilitated by the efficient photoexcited charge separation. Feasible photocatalytic mechanisms are proposed through experimental analyses and theoretical calculations. This study provides a straightforward method for designing effective CdS-based heterostructured photocatalysts, contributing to the advancement of solar-to-H 2 conversion and environmental abetment. [Display omitted] • Layered CdS nanosheets have been developed to support CoMn 2 O 4 nanoparticles. • The 2% CoMn 2 O 4 /CdS exemplified the highest photocatalytic H 2 evolution. • CoMn 2 O 4 /CdS displayed an improved photocatalytic reduction of U(VI). • Possible photocatalytic mechanisms of CoMn 2 O 4 /CdS were proposed. [ABSTRACT FROM AUTHOR]

Heterojunctions in electrode materials offer diverse improvements during the cycling process of energy storage devices, such as volume change buffering, accelerated ion/electron transfer, and better electrode structure integrity, however, obtaining optimal heterostructures with nanoscale domains remains challenging within constrained materials. A novel in situ electrochemical method is introduced to develop a reversible CuSe/PSe p‐n heterojunction (CPS‐h) from Cu3PSe4 as starting material, targeting maximum stability in potassium ion storage. The CPS‐h formation is thermodynamically favorable, characterized by its superior reversibility, minimized diffusion barriers, and enhanced conversion post K+ interaction. Within CPS‐h, the synergy of the intrinsic electric field and P‐Se bonds enhance electrode stability, effectively countering the Se shuttling phenomenon. The specific orientation between CuSe and PSe leads to a 35° lattice mismatch generates large space at the interface, promoting efficient K ion migration. The Mott‐Schottky analysis validates the consistent reversibility of CPS‐h, underlining its electrochemical reliability. Notably, CPS‐h demonstrates a negligible 0.005% capacity reduction over 10,000 half‐cell cycles and remains stable through 2,000 and 4,000 cycles in full cells and hybrid capacitors, respectively. This study emphasizes the pivotal role of electrochemical dynamics in formulating highly stable p‐n heterojunctions, representing a significant advancement in potassium‐ion battery (PIB) electrode engineering. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal dichalcogenides (2D-TMDs) possess appropriate bandgaps and interact via van der Waals (vdW) forces between layers, effectively overcoming lattice compatibility challenges inherent in traditional heterojunctions. This property facilitates the creation of heterojunctions with customizable bandgap alignments. However, the prevailing method for creating heterojunctions with 2D-TMDs relies on the low-efficiency technique of mechanical exfoliation. Sb2Te3, recognized as a notable p-type semiconductor, emerges as a versatile component for constructing diverse vertical p–n heterostructures with 2D-TMDs. This study presents the successful large-scale deposition of 2D Sb2Te3 onto inert mica substrates, providing valuable insights into the integration of Sb2Te3 with 2D-TMDs to form heterostructures. Building upon this initial advancement, a precise epitaxial growth method for Sb2Te3 on pre-existing WS2 surfaces on SiO2/Si substrates is achieved through a two-step chemical vapor deposition process, resulting in the formation of Sb2Te3/WS2 heterojunctions. Finally, the development of 2D Sb2Te3/WS2 optoelectronic devices is accomplished, showing rapid response times, with a rise/decay time of 305 μs/503 μs, respectively. [ABSTRACT FROM AUTHOR]

A rapid and accurate monitoring of hazardous formaldehyde (HCHO) gas is extremely essential for health protection. However, the high-power consumption and humidity interference still hinder the application of HCHO gas sensors. Hence, zeolitic imidazolate framework-8 (ZIF-8)-loaded Pt-NiO/In2O3 hollow nanofibers (ZPNiIn HNFs) were designed via the electrospinning technique followed by hydrothermal treatment, aiming to enable a synergistic advantage of the surface modification and the construction of a p-n heterostructure to improve the sensing performance of the HCHO gas sensor. The ZPNiIn HNF sensor has a response value of 52.8 to 100 ppm HCHO, a nearly 4-fold enhancement over a pristine In2O3 sensor, at a moderately low temperature of 180 °C, along with rapid response/recovery speed (8/17 s) and excellent humidity tolerance. These enhanced sensing properties can be attributed to the Pt catalysts boosting the catalytic activity, the p-n heterojunctions facilitating the chemical reaction, and the appropriate ZIF-8 loading providing a hydrophobic surface. Our research presents an effective sensing material design strategy for inspiring the development of cost-effective sensors for the accurate detection of indoor HCHO hazardous gas. [ABSTRACT FROM AUTHOR]

Cu2O has emerged as a promising material for sustainable hydrogen production through photoelectrochemical (PEC) water splitting, while inefficient charge separation remains one of the main challenges hindering its development. In this work, a new architecture of InAlN/Cu2O heterojunction photocathode is demonstrated by combining n‐type InAlN and p‐type Cu2O to improve the charge separation efficiency, thus enhancing PEC water‐splitting performance. The Pt/InAlN/Cu2O photoelectrode exhibits a photocurrent density of 2.54 mA cm−2 at 0 V versus reversible hydrogen electrode (VRHE), which is 3.21 times higher than that of Cu2O (0.79 mA cm−2 at VRHE). The enhanced PEC performance is explained by the larger built‐in potential Vbi of 1.43 V formed at the InAlN/Cu2O p–n junction than that in the single Cu2O photocathode (Vbi < 0.77 V), which improves the separation of the photogenerated carriers and thus relieves the bottlenecks of charge‐transfer kinetics at the electrode bulk and electrode/electrolyte interface. In this work, an avenue is opened for designing III‐nitrides/Cu2O heterojunction toward solar energy conversion. [ABSTRACT FROM AUTHOR]

Constructing heterostructural photoanodes is attractive for elevating the photoelectrochemical (PEC) performance, however, it is a long‐standing challenge to achieve highly efficient interfacial charge transfer. Herein, a CoFe metal‐thiolate framework (CoFe MTF)/Fe2O3 photoanode connected by an interfacial Fe─O─N/S bond is designed to modulate the behavior of charge carriers and improve water oxidation performance. It is disclosed that this interfacial bond functions as a direct charge transfer bridge between shallow trap states of Fe2O3 and CoFe MTF, leading to prolonged carrier recombination lifetimes (85 ns for CoFe MTF/Fe2O3 compared to 37 ns for Fe2O3) and enhanced charge transfer efficiency. Alternatively, a robust interfacial electric field is established in the CoFe MTF/Fe2O3 p–n heterojunction, facilitating efficient charge transfer. As expected, the CoFe MTF/Fe2O3 photoanode exhibits significant enhancement in water oxidation, resulting in a three‐fold increase in photocurrent density compared to pristine Fe2O3. This study highlights the significance of designing interfacially bonded heterostructural photoelectrodes to regulate the transfer characters of charge carriers. [ABSTRACT FROM AUTHOR]

The rational design of composites based on graphene/metal oxides is one of the pillars for advancing their application in various practical fields, particularly gas sensing. In this study, a uniform distribution of ZnO nanoparticles (NPs) through the graphene layer was achieved, taking advantage of amine functionalization. The beneficial effect of amine groups on the arrangement of ZnO NPs and the efficiency of their immobilization was revealed by core-level spectroscopy, pointing out strong ionic bonding between the aminated graphene (AmG) and ZnO. The stability of the resulting Am-ZnO nanocomposite was confirmed by demonstrating that its morphology remains unchanged even after prolonged heating up to 350 °C, as observed by electron microscopy. On-chip multisensor arrays composed of both AmG and Am-ZnO were fabricated and thoroughly tested, showing almost tenfold enhancement of the chemiresistive response upon decorating the AmG layer with ZnO nanoparticles, due to the formation of p-n heterojunctions. Operating at room temperature, the fabricated multisensor chips exhibited high robustness and a detection limit of 3.6 ppm and 5.1 ppm for ammonia and ethanol, respectively. Precise identification of the studied analytes was achieved by employing the pattern recognition technique based on linear discriminant analysis to process the acquired multisensor response. [ABSTRACT FROM AUTHOR]

Designing a long-lasting, highly effective, non-noble metal-free electrocatalyst for both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a strenuous task for water electrolysis. Here, in our study, an ordered NiFe-layer double hydroxide (LDH)/MoSe 2 as p-n junction material was designed using facile two-step hydrothermal process for the overall water splitting reaction. Additionally, synthesized NiFe-LDH/MoSe 2 , electrode exhibits long-term durability in both acidic and alkaline medium for HER and OER, respectively. Mott-Schottky experiments provides the insights of interfacial electron transfer, where the electron is transported from n-type NiFe-LDH to p-type MoSe 2 , resulting in the generation of the p-n junction in MoSe 2 /NiFe-LDH. As the formation LDH and transition dichalcogenides p-n junction leads to activation of the catalysts towards the OH− adsorption that may enable the water electrolysis with a low overpotential. The XPS analysis supports the electron transfer from Fe to Mo resulting in the formation synergistic back bonding between the p-n heterojunction. This strategy opens up an alternative path to a highly effective, relatively low-price catalyst for the global production of renewable energy fuels. • A highly ordered NiFe-layer double hydroxide (LDH)/MoSe 2 as p-n junction catalyst for overall water splitting reaction. • Interfacial electron transfer, through the generation of the p-n junction in NiFe-LDH/MoSe 2. • Electronic coupling through O 2 bridging (П orbitals) confirmed from XPS analysis. [ABSTRACT FROM AUTHOR]

Extending the ionic conductivity is the pre‐requisite of electrolytes in fuel cell technology for high‐electrochemical performance. In this regard, the introduction of semiconductor‐oxide materials and the approach of heterostructure formation by modulating energy bands to enhance ionic conduction acting as an electrolyte in fuel cell‐device. Semiconductor (n‐type; SnO2) plays a key role by introducing into p‐type SrFe0.2Ti0.8O3‐δ (SFT) semiconductor perovskite materials to construct p‐n heterojunction for high ionic conductivity. Therefore, two different composites of SFT and SnO2 are constructed by gluing p‐ and n‐type SFT‐SnO2, where the optimal composition of SFT‐SnO2 (6:4) heterostructure electrolyte‐based fuel cell achieved excellent ionic conductivity 0.24 S cm−1 with power‐output of 1004 mW cm−2 and high OCV 1.12 V at a low operational temperature of 500 °C. The high power‐output and significant ionic conductivity with durable operation of 54 h are accredited to SFT‐SnO2 heterojunction formation including interfacial conduction assisted by a built‐in electric field in fuel cell device. Moreover, the fuel conversion efficiency and considerable Faradaic efficiency reveal the compatibility of SFT‐SnO2 heterostructure electrolyte and ruled‐out short‐circuiting issue. Further, the first principle calculation provides sufficient information on structure optimization and energy‐band structure modulation of SFT‐SnO2. This strategy will provide new insight into semiconductor‐based fuel cell technology to design novel electrolytes. [ABSTRACT FROM AUTHOR]

Multifarious novel photocatalysts based on hybrid nanocomposites have been developed to boost photocatalytic efficiency. However, the photocatalytic property of hybrid nanocomposites is still bound by inferior thermal stability, tardive charge motion kinetics and few active sites. In this work, a convenient and facile cation exchange approach was conceptually provided for fabricating a well-designed and robust P–N heterojunction based on Mn–Zn–S–ethylenediamine hybrid nanocomposite. Such hybrids take ZnS–ethylenediamine as the skeleton, and the Mn2+ cations are superseded and inserted into the interlayer of ZnS through the cation exchange approach, thus forming the Mn–Zn–S–ethylenediamine hybrid nanocomposite. Hence, as-synthesized ZnS–Mn1.0 had a significantly promoted photoactivity for reducing p-nitroaniline (94.5%) and p-nitrotoluene (88.6%) to the corresponding amino derivatives, besides oxidizing phenol (94.6%) under simulated solar irradiation. Meanwhile, PEC measurements illustrated that the interface created by this cation exchange approach was beneficial to promoting the motion behavior and prolonging the lifetime of photo-generated charges. Through this work we hope to offer an emerging strategy to finely design and fabricate all hybrid nanocomposite-based heterostructured photocatalysts for enhancing solar-to-chemical energy conversion. [ABSTRACT FROM AUTHOR]

Antimony sulfide (Sb2S3) has a high theoretical specific capacity due to its two reaction mechanisms of conversion and alloying during the Li+-(de)intercalation process, thus becoming a promising lithium-ion battery (LIB) anode material. However, its poor inherent conductivity and large volume expansion during repeated Li+-(de)intercalation processes greatly hinder the in-depth development of Sb2S3 based LIB anode materials. Herein, an Sb2S3/SnO2@rGO composite was prepared by using an interface engineering technique involving metal-containing ionic liquid precursors, in which Sb2S3/SnO2 quantum dots (QDs) as p–n heterojunctions are uniformly anchored on the surface of reduced graphene oxide (rGO). The p–n heterogeneous interface between Sb2S3 and SnO2 QDs induces an internal electric field, promoting the electronic/ion transport during electrochemical reactions, and the QD-sized Sb2S3/SnO2 heterostructure with a larger surface area provides more active sites for Li+-(de)intercalation reactions. In addition, the rGO matrix acts as a buffer to prevent the aggregation of active Sb2S3 and SnO2 QDs, alleviate the volume expansion, and enhance the conductivity of the composite during repeated cycles. These advantages endow the designed Sb2S3/SnO2@rGO electrode with excellent reaction kinetics and good long cycling stability. As an anode material of LIBs, it can still provide a reversible specific capacity of 474 mA h g−1 after 2000 cycles at a high current density of 3.0 A g−1, which is superior to those of most of the previously reported Sb2S3-based carbon materials. The p–n heterostructure construction strategy of nano-metal sulfide/metal oxides in this work can provide inspiration for the design and synthesis of other advanced energy storage materials. [ABSTRACT FROM AUTHOR]

CsPbI3 perovskite is a promising light absorber in perovskite solar cells (PSCs) due to its suitable bandgap (Eg) and high chemical stability, but the perovskite phase is metastable in ambient atmosphere and prone to defect formation. To enhance phase stability and reduce defects, forming a low dimensional (LD) perovskite on CsPbI3 has proved effective. However, the energy levels for most of low‐conductivity LD perovskites are not very compatible with those of CsPbI3, which will impair charge separation and device performance. Herein, a new 1D perovskite (5‐Azaspiro[4.4]nonan‐5‐ium lead triiodide, ASNPbI3) with compatible energy levels and a large Eg is reported as a capping layer. The p‐type ASNPbI3 forms a p‐n heterojunction with n‐CsPbI3 with a staggered band alignment, considerably enhancing the carrier separation. Besides, by pre‐forming a ASNPbI3 at an intermediate stage, defects are suppressed in perovskite film. Consequently, the CsPbI3 PSCs based on carbon electrode without hole transporter (C‐PSCs) achieves a PCE of 18.34%, which is among the highest‐reported values for inorganic C‐PSCs. Furthermore, the hydrophobic ASNPbI3 capping layer has a high thermal stability that greatly enhances perovskite phase stability. Hence, the CsPbI3 C‐PSCs maintains 68% of its initial PCE after 400 h aging at 85°C in a N2 glovebox. [ABSTRACT FROM AUTHOR]

NiO/Ga2O3 heterojunction diodes have attracted attention for high-power applications, but their high temperature performance and reliability remain underexplored. Here, we report the time evolution of the electrical properties in the widely studied p-NiO/n-Ga2O3 heterojunction diodes and formation of NiGa2O4 interfacial layers at high temperatures. Results of our thermal cycling experiment show an initial leakage current increase which stabilizes after sustained thermal load, due to reactions at the NiO–Ga2O3 interface. High-resolution TEM microstructure analysis of the devices after thermal cycling indicates that the NiO–Ga2O3 interface forms a ternary compound at high temperatures, and thermodynamic calculations suggest the formation of the spinel NiGa2O4 layer between NiO and Ga2O3. First-principles defect calculations find that NiGa2O4 shows low p-type intrinsic doping and hence can serve to limit electric field crowding at the interface. Vertical NiO/Ga2O3 diodes with intentionally grown ∼5 nm thin spinel-type NiGa2O4 interfacial layers show an excellent device ON/OFF ratio of >1010 (± 3 V), VON of ∼1.9 V, and increased breakdown voltage of ∼1.2 kV for an initial unoptimized 300 μm diameter device. These p–n heterojunction diodes are promising for high-voltage, high temperature applications. [ABSTRACT FROM AUTHOR]