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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 proposed model structure, featuring a gold (Au) nano‐island film (GNIF) integrated with a vertically stacked van der Waals heterojunction and offering an elegant platform for high‐performance, efficient, and sensitive photodetection across a broad spectral range, is designated as GNIF‐MoS₂/p‐Ge(MoS2 = Molybdenum disulfide, p‐Ge = p type germanium). The GNIF is fabricated via ultrathin film deposition, based on the surface dewetting properties of MoS2. The as‐fabricated photodetector (PD), offering ≈20 times reduction in dark current and characterized by wavelength‐dependent high responsivity (R(λ)), photoconductive gain (G(λ)), and detectivity (D(λ)), respond to a broad spectral range from visible light (400 nm) to short wave infrared (SWIR) (1600 nm). The ultrahigh transient response (τr) is found to be ≈2.5 and 16 µs for the 470 (visible light) and 1550 (SWIR) nm wavelengths, respectively, resulting in 3‐dB bandwidths of up to ≈48 kHz, which is considered high for such devices. To understand the inherent mechanisms of broadband detection and the high photoresponse and ultrafast transient response of PDs, a meticulous investigation is conducted on the wavelength‐dependent behaviors, depletion width changes, and material properties. The results provide valuable insights and a basis for the construction of suitable PDs based on nanometer‐thin metal films, 2D semiconductors, and a 3D hybrid structure. [ABSTRACT FROM AUTHOR]

Gas sensors with the p–n heterojunction have demonstrated distinct sensing responses to reducing gases, yet a clear understanding of the reaction pathways and selective adsorption mechanisms for specific gas components remains elusive, impeding practical applications. In this study, we constructed an atomic-level NiO–In 2 O 3 heterojunction and explored its adsorption behaviors and sensing properties for CO and H 2 by first-principles calculations. Analysis of its electronic properties, focusing on binding energy, differential charge density, and density of states, confirmed the creation of a highly stable NiO–In 2 O 3 heterojunction and alterations in the coordination environment of the surface-active atoms. These changes potentially led to differences in the affinity between the gas molecules and the adsorption sites. The calculations of the adsorption properties revealed that the adsorption capacity of H 2 is relatively weak compared to the strong interactions between CO and heterojunction surface atoms, indicating a readily variable reaction pathway for H 2. Consequently, the adsorption configuration at the interface site on the NiO–In 2 O 3 heterojunction surface exhibited a predominantly p-type response for CO and a unique n-type response for H 2. This interfacial effect of the heterojunction is crucial for the selective adsorption of CO and H 2. Furthermore, the opposite response signal was verified by gas sensing tests, which also presented the superior stability of the NiO–In 2 O 3 sensor. The p–n heterojunction of the corresponding composites was effectively characterized. This research offers new insights into the selective adsorption mechanism, paving the way for the development of gas sensors. [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]

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]

Broadening spectral response range to realize the full spectrum photocatalysis is crucial to develop photocatalysts with satisfactory light-energy conversion ability. A full-spectrum driven p-n heterojunction photocatalytic system was rationally designed through introducing the Er3+/Yb3+ co-doped BiOBr with up-conversion effect as the collector of near infrared light and photocatalysts substrate. Meanwhile, Cu3Mo2O9 with the photothermal effect as a heat source to accelerate the reaction at the surface through absorbing the near infrared light. The photocatalytic activity of BiOBr:Yb3+,Er3+/Cu3Mo2O9 composite was markedly strengthened under visible and near infrared light irradiation, and the BiOBr:Yb3+,Er3+/Cu3Mo2O9-5 composite displayed the optimal photodegradation activities for 0.03372 min−1 and 0.058 h−1, being 2.3-folds and 2.4-folds than that of pure BiOBr:Yb3+,Er3+ under the visible and near infrared light, respectively. The position of doped ions (Yb3+ and Er3+) in BiOBr:Yb3+,Er3+ was determined from the X-ray absorption fine structure spectra. And the reasonable mechanism of p-n heterojunction was proposed base on the results of experimental and density functional theory calculation. This work provides a rational strategy for the design and development of full-spectrum heterojunction photocatalysts with the up-conversion and photothermal effects to increase the photocatalytic performance. [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]

As cocatalysts play important roles in enhancing the catalytic performance, designing and fabricating highly active cocatalysts is an effective approach to improving photocatalytic H2 production. In this work, transition metal phosphides (including Fe2P, Co2P, and Ni2P) with nanoscale structures are synthesized by the solvothermal method, which can largely enhance the photocatalytic activity and stability of CdS nanorods as cocatalysts. By optimizing the synthesis and reaction conditions, 10% Co2P/CdS achieved the highest H2 production, about 29.24 mmol·g–1·h–1 in the lactic acid solution, which was 21.5 and 3.0 times higher than that of CdS (1.36 mmol·g–1·h–1) and 1% Pt/CdS (9.63 mmol·g–1·h–1), respectively. Testing by many characterizations, not only the reasons for different activities for TMPs/CdS but also the enhanced reasons of Co2P/CdS are explored. The results indicated that the non-noble metal Co2P cocatalyst not only enhanced the visible light absorption of CdS but also promoted the effective separation of photogenerated charge carriers. This work contributes to the further development of TMPs as low-cost and highly active cocatalysts for CdS-based photocatalysts. [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]

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]

The development of a sensor capable of selectively detecting hydrogen levels in the environment holds immense importance for ensuring the safer utilization of hydrogen energy. In this study, a hydrogen sensor made of Ce-doped single-layer graphene (SLG)/SnO2 composite material was fabricated using a hydrothermal method. The study examined the impact of varying Ce doping concentrations on the hydrogen sensing capabilities of the SLG/SnO2 matrix. The results show that the SLG/SnO2 hydrogen sensor doped with 2 mol% Ce demonstrated optimal performance at a humidity of 20%. It operated most efficiently at 250 °C, with a response of 2.49, representing a 25.75% improvement over the undoped sample. The response/recovery times were 0.46/3.92 s, which are 54.9% shorter than those of the undoped sample. The enhancement in hydrogen sensitivity stems from the synergistic effect of Ce and SLG, which facilitates the coexistence of n–n and p–n heterojunctions, thereby increasing carrier mobility and refining grain structure. Analysis via X-ray photoelectron spectroscopy (XPS) reveals that Ce increases the material's oxygen vacancy concentration, enhancing its hydrogen sensitivity. Ce-doped SLG/SnO2, with its robust hydrogen sensitivity, represents one of the leading candidates for future hydrogen gas sensors. [ABSTRACT FROM AUTHOR]

Rapid recombination of charge carriers in semiconductors is a main drawback for photocatalytic oxidative coupling of methane (OCM) reactions. Herein, we propose a novel catalyst by developing a p–n junction titania–silicon nanowires (TiO2/SiNWs) heterostructure. The structure is fabricated by atomic layer deposition of TiO2 on p-type SiNWs. The TiO2/SiNWs heterostructure exhibited an outstanding OCM performance under simulated solar light irradiation compared to the single components. This enhanced efficiency was attributed to the intrinsic electrical field formed between n-type TiO2 and p-type SiNWs, which forces generated charge carriers to move in opposite directions and suppresses charge recombination. Besides, surface morphology and optical properties of the the p–n TiO2/SiNWs catalyst are also beneficial for the photocatalytic activity. It is expected that the results of this study will provide massive guidance in synthesizing an efficient photocatalyst for CH4 conversion under mild conditions.

Two-dimensional (2D) Ti3C2T x MXene-based materials have attracted widespread attraction in the field of energy storage owing to their high conductivity and accordion-like structure. However, challenges such as restacking and oxidative degradation of the Ti3C2T x MXene structure lead to poor stability, low conductivity, low specific capacitance and, consequently, a low specific energy, hindering their extensive adoption at an industrial scale. In this study, a ternary MXene/polyaniline (PANI)/ZnO (MPZ) composite has been synthesized via surface engineering of two-dimensional (2D) MXene using one-dimensional (1D) PANI nanowires and ZnO nanoparticles to enhance its specific energy and stability while sustaining its specific power. 1D PANI nanowires and ZnO nanoparticles act as spacers to prevent restacking, while also exposing the suppressed redox active sites of 2D MXene and preventing it from being oxidized by forming a porous conductive network all over the surface of the MXene. PANI and ZnO also provide additional electroactive redox sites by forming p–n heterojunctions, thus enhancing faradaic redox reactions and the specific capacitance of the MPZ composite. As a result, the overall electrochemical performance and stability of the ternary MPZ composite are enhanced due to the synergistic interactions among the individual components within the ternary MPZ composite. At a low current density of 0.1 A g−1, the ternary MPZ composite exhibited a maximum specific capacitance of 651.96 F g−1 and a highest specific energy of 32.59 Wh Kg−1 while maintaining a specific power of 60 W Kg−1 as compared to MXene and binary MP composite. Furthermore, it showcased exceptional cyclic stability over 10 000 cycles with 94.75% and 92.95% capacitive retention at 0.6 A g−1 current density and 40 mV s−1 scan rate, respectively. Thus, this current study highlights an effective strategy to enhance the specific energy of MXene-based supercapacitors through surface engineering and the construction of p–n heterojunctions within the composite. [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]

MnWO4/WO3 p-n heterojunction films were fabricated using a one-step method consisting of the plasma electrolytic oxidation (PEO) of titanium in homogeneous electrolytes containing paratungstate ions and stable water-soluble EDTA-chelated manganese. The influences of the formation current density and W:Mn molar ratio of the electrolyte, which was varied from 1:2 to 2:1, on the composition, morphology, and optical and photocatalytic properties of the resulting coatings were studied. X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, and ultraviolet diffuse reflectance spectroscopy were used to characterize the formed composites. Regardless of the W:Mn ratio of the electrolyte, the coatings contained crystalline t-WO3 and m-MnWO4. Depending on the formation conditions, the optical band gap energies of the composites varied from 2.63 to 3.01 eV. The largest absorption red shift and lowest band gap energy were observed in the film composite formed in an electrolyte with W:Mn = 2:1, at a current density of 0.2 A cm−2. Composites obtained in electrolytes with W:Mn ratios of 2:1 and 1:1 exhibited photocatalytic activity in the degradation of rhodamine C and methyl orange dyes in the presence of 10 mmol L–1 H2O2 under ultraviolet and visible light irradiation. The role of hydrogen peroxide in this dye degradation on PEO-coated composites under light irradiation is discussed.

Abstract This research presents a compact portable electronic gas sensor that can be monitored through a smartphone application. The smart sensor utilizes three state-of-the-art sensors. The sensors integrate an ESP8266 microcontroller within the same device. This facilitates their integration with the electronics and enhances their performance. Herein, primarily focuses on utilizing the sensor to detect carbon monoxide. This article outlines the fabrication process of a gas sensor utilizing a P–N heterojunction, eliminating the need for a binder. The sensor consists of CuO/copper foam nanowires and hierarchical In2O3. In order to verify the system’s functionality, it underwent testing with various levels of CO concentrations (10–900 ppm), including particular tests designed to examine the device’s performance in different humidity and temperature circumstances. A mobile application for the provision of monitoring services has been developed at last. To process the information obtained from the gas sensor, an algorithm has been constructed, trained, and integrated into a smartphone for this purpose. This research demonstrated that a smartphone-coupled gas sensor is a viable system for real-time monitoring and the detection of CO gas.

Faradaic‐mode organic electrochemical transistors (OECT) are promising but usually need hundreds of millivolts to sustain redox reactions. Decrease or even removal of the voltage penalty is highly desirable. Herein, the Faradic regime of the OECT is broadened toward zero bias by integrating a p‐n heterojunction of Cu2S‐diethylenetriamine (DETA)‐CdS for efficient photogating of poly(3,4‐ethylenedioxythiophene): poly(styrene sulfonate) channel. Upon light illumination, it is found that an obvious Faradaic process is evolved at the gate/electrolyte interface under zero gate bias, suggesting the potential of sensitive amperometric biodetection with enhanced signal resolution. At the Cu2S‐DETA‐CdS/liquid interface, a biosensing process is introduced, combining with a DNA walker and enzymatic biocatalytic precipitation to produce a target‐dependent diffusion barrier, modulating the amperometric output with enhanced signal variations under light irradiation compared to that in the dark. The proposed system achieves the desired analytical performance for representative target miRNA‐10b with a low detection limit of 0.21 fM. This work features a light‐mediated OECT device with enhanced signal resolution and provides new operational paradigms and insights for novel optoelectronics interfacing with biological systems. [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]

MnWO4/WO3 p-n heterojunction films were fabricated using a one-step method consisting of the plasma electrolytic oxidation (PEO) of titanium in homogeneous electrolytes containing paratungstate ions and stable watersoluble EDTA-chelated manganese. The influences of the formation current density and W:Mn molar ratio of the electrolyte, which was varied from 1:2 to 2:1, on the composition, morphology, and optical and photocatalytic properties of the resulting coatings were studied. X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, and ultraviolet diffuse reflectance spectroscopy were used to characterize the formed composites. Regardless of the W:Mn ratio of the electrolyte, the coatings contained crystalline t-WO3 and m-MnWO4. Depending on the formation conditions, the optical band gap energies of the composites varied from 2.63 to 3.01 eV. The largest absorption red shift and lowest band gap energy were observed in the film composite formed in an electrolyte with W:Mn = 2:1, at a current density of 0.2 A cm-2. Composites obtained in electrolytes with W:Mn ratios of 2:1 and 1:1 exhibited photocatalytic activity in the degradation of rhodamine C and methyl orange dyes in the presence of 10 mmol L-1 H2O2 under ultraviolet and visible light irradiation. The role of hydrogen peroxide in this dye degradation on PEO-coated composites under light irradiation is discussed. [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]

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]

[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]

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]

Organic pollutant detection has caused widespread concern regarding due to their potential environmental and human health risks. In this work, a nitrogen-doped titanium dioxide/silver oxide (N-TiO2/Ag2O) composite has been designed as a sensitive photoelectrochemical (PEC) monitoring platform of organic dyes. Sensitive determination relies on the outstanding PEC performance of N-TiO2/Ag2O. The improved PEC performance stems from the effective separation of photocarriers and the extended light response range provided by the narrowing bandgap and a p–n junction with N-TiO2/Ag2O. The N-TiO2/Ag2O electrode exhibits a photocurrent density of up to 2.2 mA/cm2, demonstrating three times increase compared with the photocurrent density observed with the pure TiO2 film. The linear detection range for rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) is 0.2 ng/mL to 10 μg/mL with an ultrasensitive detection limit of 0.2 ng/mL without bias voltage. Due to the outstanding photocurrent density and sensitive response to organic pollutants, the N-TiO2/Ag2O PEC sensor provided a promising analytical method to detect environmental organic dyes. [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]

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]

BiOCl/KBiO3 p-n heterostructures with hierarchical mesoporous architectures were successfully synthesized via a facile in situ method. The X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) results indicate the formation of heterojunctions between BiOCl and KBiO3. The photocatalytic performance of the as-prepared samples was investigated by the degradation of dye Rhodamine B (RhB) under visible light irradiation. BiOCl/KBiO3 composite has never been used to photodegrade the RhB which is a common dye and very difficult to degrade. The results demonstrated that KBiO3 combined with proper amount of BiOCl nanosheets exhibited high efficiency in the photocatalytic process, and BiOCl/KBiO3 with the molar ratio of 70/30 demonstrated the highest photocatalytic activity due to its large surface area, excellent charge separation characteristics and the suppressed recombination of electron-hole pairs. The results of active species detection reveal that the superoxide radical anions (O2-), hydroxyl free radicals (·OH), photogenerated holes (h+) and photogenerated electrons (e-) reactive species work together for the photocatalytic degradation of RhB. A possible and new mechanism of photocatalysis that differs from other teams was also explored and proposed. The present study will benefit the development of the new p-n heterojunction photocatalysts and would be of great importance to meet ever-increasing environmental demands in the future.

Facilitating the separation of photogenerated charges is a crucial process in photocatalytic degradation of pollutants. In this study, Bi2O3/In2O3 composites were prepared using a co-precipitation method and subsequently calcined at 400 ℃ for 1 h. The Mott-Schottky curves confirmed a p(Bi2O3)-n(In2O3) heterojunction was yielded. Due to the significant difference in Fermi levels between Bi2O3 and In2O3, an internal electric field was established at the interface, with field lines directed from In2O3 to Bi2O3. Under illumination, the excited electrons accumulated in the conduction band (CB) of In2O3, while holes gathered in the valence band (VB) of Bi2O3, promoting charge separation and enhancing quantum efficiency. The composite material exhibited the highest photocatalytic activity when the atomic percentage of Bi to In was 1:1, with the first-order reaction rate constant of BI-1 increasing to 0.0149 min−1, which is 4.3 and 4.4 multiples higher than that of pure In2O3 and pure Bi2O3. Recycling experiments demonstrated that the photocatalytic composite possesses good reusability and structural stability.

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]

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]

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]

The direct conversion of atmospheric CO2 into fuel via photocatalysis exhibits significant practical application value in advancing the carbon cycle. In this study, we established an electro-assisted photocatalytic system with dual compartments and interfaces, and coated Ag nanoparticles on the titanium nanotube arrays (TNTAs) by polydopamine modification. In the absence of sacrificial agent and alkali absorption liquid conditions, the stable, efficient and highly selective conversion of CO2 to CO at the gas-solid interface in ambient air was realized by photoelectric synergy. Specifically, with the assistance of potential, the CO formation rates reached 194.9 µmol h-1 m-2 and 103.9 µmol h-1 m-2 under ultraviolet and visible light irradiation, respectively; the corresponding CO2 conversion rates in ambient air were 30% and 16%, respectively. The excellent catalytic effect is mainly attributed to the formation of P-N heterojunction during the catalytic process and the surface plasmon resonance effect. Additionally, the introduction of solid agar electrolytes effectively inhibits the hydrogen evolution reaction and improves the electron utilization rate. This system promotes the development of photocatalytic technology for practical applications and provides new insights and support for the carbon cycle. [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]

Star-like BiVO4 and Cu2O nanocubes were prepared by hydrothermal method and chemical reduction, respectively, and Cu2O/BiVO4 p-n heterojunction with different mass ratios of Cu2O to BiVO4 (3:1, 1:1, 1:3) were synthesized via facile physical mixing. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflection spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of the Cu2O/BiVO4 composites was evaluated by degradation of tetracycline hydrochloride (TC) under simulated solar illumination. Owing to the fast charge transfer between n-type BiVO4 and p-type Cu2O, Cu2O/BiVO4 composites exhibited superior photocatalytic activity. When the mass ratio of Cu2O to BiVO4 was 1:3, the highest degradation efficiency of TC reached 78.9% within 24 min. [ABSTRACT FROM AUTHOR]

The combination of two-dimensional material MXene and one-dimensional metal oxide semiconductor can improve the carrier transmission rate, which can effectively improve sensing performance. We prepared a trimethylamine gas sensor based on MoO3 nanofibers and layered Ti3C2Tx MXene. Using electrospinning and chemical etching methods, one-dimensional MoO3 nanofibers and two-dimensional Ti3C2Tx MXene nanosheets were prepared, respectively, and the composites were characterized via XPS, SEM, and TEM. The Ti3C2Tx MXene–MoO3 composite material exhibits excellent room-temperature response characteristics to trimethylamine gas, showing high response (up to four for 2 ppm trimethylamine gas) and rapid response–recovery time (10 s/7 s). Further, we have studied the possible sensitivity mechanism of the sensor. The Ti3C2Tx MXene–MoO3 composite material has a larger specific surface area and more abundant active sites, combined with p–n heterojunction, which effectively improves the sensitivity of the sensor. Because of its low detection limit and high stability, it has the potential to be applied in the detection system of trimethylamine as a biomarker in exhaled air. [ABSTRACT FROM AUTHOR]

A novel p-n heterojunction photocatalyst of CoMoO 4 /NiS-3 was constructed by electrostatic adsorption (In CoMoO 4 /NiS-3, the content of CoMoO 4 accounts for 30%). Through SEM and crystal structure, it can be seen that the composite catalyst has a starry flower morphology and is successfully synthesized. The fluorescence emission spectra show that CoMoO 4 /NiS-3 can accelerate the separation rate of photogenerated carriers. The electron transfer mechanism can be determined by ultraviolet characterization and electrochemical methods. Hydrogen evolution experiments can be observed that the amount of hydrogen evolution by the composite catalyst CoMoO 4 /NiS-3 is 225.1 μmol, which is 2.74 and 4.89 times higher than that of the CoMoO 4 and NiS catalysts, respectively. Through the control of the starry flower morphology and the contact interface of p-n heterojunction, the internal electric field is effectively constructed to inhibit the recombination rate of photogenerated carriers, which provides a powerful theoretical model for high performance hydrogen evolution reaction. The formation of p-n heterojunction effectively improves the transmission path of photogenerated carriers and greatly improves the performance of photocatalytic hydrogen evolution. [Display omitted] • The p-n heterojunction between NiS and CoMoO 4 has good stability. • Dispersion of NiS on CoMoO 4 is important for the hydrogen evolution reaction activity. • The electron transport path and hydrogen evolution mechanism of CoMoO 4 /NiS composite catalyst are proposed. • High-efficiency hydrogen evolution is realized through CoMoO 4 /NiS heterojunction. [ABSTRACT FROM AUTHOR]

Slow hole transfer is one of the important reasons for limited charge separation. This work reports a strategy to construct a p-n heterojunction biomimetic hollow composite (Cu 2-x S@ZGS) by combining Cu 2-x S (composed of Cu 7.2 S 4 and Cu 1.96 S) with Zn 3.74 Ga 1.02 S 5.24 (ZGS) to promote charge space separation and improve the photocatalytic hydrogen production activity of ZGS. Cu 2-x S@ZGS shows significantly enhanced photocatalytic hydrogen production. The hydrogen production rate of 7 %Cu 2-x S@ZGS is 44 and 3 times higher than that of Cu 2-x S and ZGS under simulated sunlight and is 36, 30, and 25 times higher than that of Cu 2 S, Cu 2-x S, and ZGS under visible-light-driven, respectively. The biomimetic hollow structure provides the site of spatial separation for the redox reaction. The Cu 2-x S/ZGS p-n heterojunction promotes the migration of photogenerated holes to the inner Cu 2-x S, where oxidation reactions occur, and it promotes the migration of photogenerated electrons to the outer ZGS, where the proton reduction reaction occurs, improving the spatial separation efficiency of charges. In addition, the Cu vacancies of Cu 2-x S further promote the rapid transfer of h+ and the S vacancies of ZGS expose the active site to enhance hydrophilicity. This study provides design ideas and synthesis guidance for heterojunction catalysts that achieve photogenerated charge spatial separation. [Display omitted] • The biomimetic Cu 2-x S@ZGS hollow composite with p-n heterojunctions was developed. • p-type Cu 2-x S extracts photogenerated holes to improve carrier's transfer. • n-type ZGS with S defects has a larger surface area and hydrophilia. • The p-n heterojunction hollow structure achieves the spatial separation of charges. [ABSTRACT FROM AUTHOR]

A composite of two or more materials usually results in enhanced specific properties. In this paper, a kind of composite material composed of Bi2WO6 with highly exposed {010} facets and 2D‐Co3O4 was prepared by a one‐pot reaction and then applied to decontaminate hydrocortisone in wastewater. The Bi2WO6/Co3O4 composite possessed a rose‐like surface microtopography self‐assembled from Bi2WO6 and Co3O4 nanosheets. The micro‐interface analysis showed that {110} facets of Co3O4 and {010} facets of Bi2WO6 were glued in situ and formed heterojunction. Additionally, the removal ability of hydrocortisone through Bi2WO6/Co3O4 varied under different light sources, which was 85.0 % under ultraviolet light and 97.3 % under visible light within 60 min. It was considered that Bi2WO6/Co3O4 was similar to a traditional heterojunction and the major reactive species was H2O2 under ultraviolet light, while it played a role as a Z‐scheme photocatalyst and the major reactive species was ⋅OH under visible light. Finally, product analysis of hydrocortisone demonstrated that the dexter chain broke whatever under ultraviolet or visible light, but the breakage of parent nucleus appeared only under visible light. This research revealed the enhanced catalytic properties of p‐n heterojunction catalysts and indicated the specifically exposed facets are promising for organic contaminants in water. [ABSTRACT FROM AUTHOR]

Designing photocatalysts with p-n heterojunction structures is an effective way to boost the separation of photogenerated carriers and stimulate the photocatalytic degradation activity. Herein, an efficient visible-light responsive AgI/BiSI p-n heterojunction photocatalyst was successfully constructed. X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and electrochemical measurements confirmed that the AgI/BiSI p-n heterojunction structure was beneficial to the separation and transfer of photogenerated carriers, promoting the generation of main active species (•O2− and h+). Furthermore, the photocatalytic degradation rate constants of Acid Red 1 (0.4699 min−1) and metronidazole (0.0730 min−1) over the optimal AgI/BiSI were about 8.4 and 3.0 times higher than those over pure AgI, respectively. This work provides a heterojunction engineering strategy to design high-efficient photocatalysts for the degradation of refractory organic pollutants.

The development of a sensor capable of selectively detecting hydrogen levels in the environment holds immense importance for ensuring the safer utilization of hydrogen energy. In this study, a hydrogen sensor made of Ce-doped single-layer graphene (SLG)/SnO2 composite material was fabricated using a hydrothermal method. The study examined the impact of varying Ce doping concentrations on the hydrogen sensing capabilities of the SLG/SnO2 matrix. The results show that the SLG/SnO2 hydrogen sensor doped with 2 mol% Ce demonstrated optimal performance at a humidity of 20%. It operated most efficiently at 250 °C, with a response of 2.49, representing a 25.75% improvement over the undoped sample. The response/recovery times were 0.46/3.92 s, which are 54.9% shorter than those of the undoped sample. The enhancement in hydrogen sensitivity stems from the synergistic effect of Ce and SLG, which facilitates the coexistence of n–n and p–n heterojunctions, thereby increasing carrier mobility and refining grain structure. Analysis via X-ray photoelectron spectroscopy (XPS) reveals that Ce increases the material’s oxygen vacancy concentration, enhancing its hydrogen sensitivity. Ce-doped SLG/SnO2, with its robust hydrogen sensitivity, represents one of the leading candidates for future hydrogen gas sensors.

In recent years, water pollution caused by organic pollutants and antibiotic residues has become increasingly serious, posing a serious threat to human health and ecosystems. In this paper, Co–BiVO 4 /Bi 2 O 3 heterojunction was successfully prepared by electrospinning of Co3+ doped monoclinic BiVO 4 nanofibers and Bi 2 O 3. The photocatalytic degradation of chlortetracycline hydrochloride (CTC·HCl) and 2-mercaptobenzothiazole (MBT) in water was tested by simulating visible light conditions. The degradation efficiency of CTC·HCl by 3Co–BiVO 4 /Bi 2 O 3 -0.8 reached 90.5 % within 30 min, and the degradation rates were 3.93 and 7.06 times that of BiVO 4 and Bi 2 O 3 , respectively. At the same time, the degradation efficiency of MBT by 3Co–BiVO 4 /Bi 2 O 3 -0.8 reached 97.7 % within 40 min, and the degradation rates were 8.93 and 41.80 times that of BiVO 4 and Bi 2 O 3 , respectively. In addition, the photocatalytic performance of the catalyst and potassium persulfate (PS) co-system on pollutants was investigated. When 0.5 mM PS and a small amount of 3Co–BiVO 4 /Bi 2 O 3 -0.8 catalyst were added, the degradation efficiency of CTC·HCl and MBT could reach 87.6 % and 92.8 % in a short time. Furthermore, the work function and difference of the material were calculated by density functional theory (DFT), and the charge transfer mechanism of the p-n heterojunction was further determined. Finally, the intermediate products, degradation pathways and reaction mechanisms of MBT degradation were analyzed in detail by high performance liquid chromatography-mass spectrometry (HPLC-MS). Therefore, this study provides a potential effective way for the treatment of water pollution. [Display omitted] [ABSTRACT FROM AUTHOR]

This study reports PANI/WS2 gas-sensitive sensing materials synthesized with in situ polymerization for high-performance, wearable, flexible gas sensors. The gas sensors were constructed on flexible interdigital electrodes (IDEs) using a drop-coating self-assembly method. Due to the p–n junction structure formed by polyaniline (PANI) and tungsten disulfide (WS2), PANI doped with 2 wt % WS2 exhibits excellent properties for flexible sensors at room temperature, including high sensitivity, flexibility, and selectivity. The flexible sensor remains sensitive to NH3 at 100 ppb and maintains a good sensing performance under bending conditions. The mechanism of improved gas-sensitive performance due to p–n junctions has been investigated. In addition to gas sensing applications, a real-time human breath testing device was designed based on a PANI/WS2 composite membrane, demonstrating its potential application in health assessment. [ABSTRACT FROM AUTHOR]