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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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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 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]

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]

Transition metal sulfides are promising electrode materials for supercapacitors (SCs), but they still suffer from sluggish electrochemical kinetics and volume changes during the electrochemical process. Herein, two-dimensional (2D) nickel metal–organic framework (Ni-MOF) nanosheets coated on MnS hollow microspheres to form a MnS@Ni-MOF p-n heterojunction have been constructed for SCs. The core–shell structure can provide abundant electroactive sites and void space benefits electrolyte ions diffusion. The charge redistribution in the p-n junction can form space-charge regions and a built-in field therein, which facilitates charge transfer, thereby enhancing intrinsic activity. Benefiting from these advantages, the optimal MnS@Ni-MOF-5 (12 h) displays outstanding specific capacity (687.0 C g–1 at1 A g–1), surpassing solitary MnS or Ni-MOF. Besides, the asymmetric SC comprising MnS@Ni-MOF-5 (12 h) demonstrates satisfactory energy density (maximal 28.7 W h kg–1) and stability (86.2%, 10,000 cycles at 5 A g–1). [ABSTRACT FROM AUTHOR]

Although SnO2 nanomaterials have been leading components of semiconductor gas sensors, their long-standing challenges of high working temperatures limit their practical application for ultralow-power-consumption room-temperature sensing. In this study, Au and Pt bimetallic nanoparticles were used to fabricate a MoS2/AuPt/SnO2 nanocomposite device by interfacially engineering a MoS2/SnO2 nanostructure. Owing to the unique structure and electrical properties, the as-fabricated MoS2/AuPt/SnO2 device exhibits a remarkable sensing response (2.22), short response time (20 s), and excellent baseline recovery (8 s) to 10 ppm NO2 gas at 23 ± 2 °C. Meanwhile, the MoS2/AuPt/SnO2 device possesses high sensitivity, a low detection limit (20 ppb), commendable reversibility, appreciable stability, and excellent selectivity against ammonia, carbon monoxide, ethanol, isopropanol, and acetone gases. The superior sensing characteristics of the MoS2/AuPt/SnO2 nanocomposite device are attributed to the modulation effect of the Schottky junction and p–n heterojunction on the potential barrier, highly efficient interfacial electron transport, and edge-enriched structure, which provide abundant active adsorption sites. This work will advance the evolution of room-temperature gas-sensitive nanomaterials and render them promising for applications in ultralow power-integrated sensors. [ABSTRACT FROM AUTHOR]

Owing to the confinement of ZnO in the photocatalytic application: the wide bandgap, the rapid photogenerated carriers recombination, and the expensive cost for the catalyst separation from the wastewater, the p-n heterojunction of NiFe2O4 magnetic phase and ZnO is considered to improve the photocatalytic efficiency and the catalyst separation by the external magnetic. The NiFe2O4/ZnO composites with 0–12 wt% of NiFe2O4 were prepared by an ordinary process and characterized using XRD, Raman, SEM, EDS, TEM, HRTEM, UV–Vis spectroscopy, and PL techniques. The Raman spectra confirm the crystallinity of ZnO and NiFe2O4, including their defects. As increasing NiFe2O4 incorporation, the crystallite size of ZnO phase depicts a lower value with changing from 53.14 to 40.49 nm, whereas NiFe2O4 phase reveals a greater value of 60.61–141.55 nm. The dislocation density, lattice constants, and atomic coordinates are also discussed in terms of ion diffusion. The morphology analysis reveals ZnO particles on the surface of NiFe2O4 microcrystals, confirming the p-n heterojunction formation. The energy bandgap of the as-synthesized samples is in the range of 1.52–2.85 eV, suggesting to the visible light photocatalysis. The prominent PL spectrum indices the forming of Zn interstitial defect state. Under the visible light irradiation, the dye degradation was investigated as a result of the photoreduction percentage and catalyst dosage. With prepared by a facile process, 12 wt% NiFe2O4-loaded ZnO displayed the high methylene blue degradation of 96.96 % within 150 min under visible light irradiation, confirming an excellent photocatalyst. Due to the microstructural composite, the active surface site and the p-n heterojunction were elucidated as the principal mechanism for the difference in reaction time. The dye degradation was discussed in association with the structural constants, morphology, and defects. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate a new, simple, one-pot combustion synthesis technique for creating sulphur-based CuS/ZnS p-n heterojunction nanocomposite photocatalysts. This study examined the photocatalytic activity and reusability of these nanocomposites in removing rhodamine B (RhB) dye under visible-light irradiation. Various methods of characterisation were employed to determine the properties of the materials, including particle morphology, crystalline phases, and bandgap energy. The intrinsic reaction parameters, such as catalyst loading, the pH level of the solution, and initial pollutant concentration, were varied to establish the optimal photodegradation conditions. The results showed that a binary CuS/ZnS catalyst with a 10 g L−1 loading, at pH 5, degraded 97% of 5 ppm RhB dye after 270 min of visible light irradiation. Additionally, this composite catalyst exhibited excellent chemical stability and reusability, achieving 83% RhB dye removal after five recycling runs. Scavenger tests identified the photogenerated holes (h+) and superoxide free radicals (•O2) as the primary reactive species responsible for degradation. This study provides valuable insight into the design of highly efficient nanomaterials for removing organic pollutants in wastewater, and a possible reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

Extensive consumption, toxicity and bioaccumulation of malathion (MLT) and lindane (γ-HCH) pesticides collectively attract the world's attention. Herein, the nanocomposite of chitosan wrapped NiO@ZnO was synthesized by a green methodology using Azadirachta indica leaves extract. Structural and morphological analysis of chitosan-NiO@ZnO showed hollow sphere-flake shaped image adsorbed on a solid chitosan surface with a large surface area of 73 m2g−1. A decrease in values of lattice strain, dislocation density and crystallite size described the imperfection in crystal geometry and new peaks in FT-IR spectra at 698 cm−1 and 448 cm−1 of Ni–N and Zn–N, which respectively confirm the coupling. Chitosan-NiO@ZnO and individual nanoparticles (NiO and ZnO) were well-characterized and utilized for degradation MLT and γ-HCH under direct sunlight and dark conditions. The highest degradation of pesticides (above 94%) resulted with 2 mg L−1 and 10 mg L−1 of MLT (π–π) and γ-HCH, respectively with a 20 mg catalyst dose, and pH of ~ 7 under daylight exposure (5 h). Chitosan-NiO@ZnO substantially suppressed the half-life of the targeted pesticides (MLT: 0.48 h; HCH 0.51 h) and demonstrated the first-order kinetics with a high adsorption capacity, Xm (MLT: 14.5 mg g−1 and γ-HCH 20.7 mg g−1), which also confirmed the strong binding with the pesticides, followed by their conversion into safer and smaller metabolites. The charge separation mechanism was elucidated by UV reflectance and photoluminescence data. Hydroxyl radicals were most frequently responsible for the degradation of pesticides as confirmed by scavenger analysis. The synthesized green-nano photocatalyst showed high reusability (up to 10th cycles), sensitivity and stability within the degradation process, presumably making it suitable for industrial applications. [ABSTRACT FROM AUTHOR]

In this study, a Z-Scheme WO3/CoO p-n heterojunction with a 0D/3D structure was designed and prepared via a simple solvothermal approach to remove the combined pollution of tetracycline and heavy metal Cr(VI) in water. The 0D WO3 nanoparticles adhered to the surface of the 3D octahedral CoO to facilitate the construction of Z-scheme p-n heterojunctions, which could avoid the deactivation of the monomeric material due to agglomeration, extend the optical response range, and separate the photogenerated electronhole pairs. The degradation efficiency of mixed pollutants after a 70 min reaction was significantly higher than that of monomeric TC and Cr(VI). Among them, a 70% WO3/CoO heterojunction had the best photocatalytic degradation effect on the mixture of TC and Cr(VI) pollutants, and the removing rate was 95.35% and 70.2%, respectively. Meanwhile, after five cycles, the removal rate of the mixed pollutants by the 70% WO3/CoO remained almost unchanged, indicating that the Z-scheme WO3/CoO p-n heterojunction has good stability. In addition, for an active component capture experiment, ESR and LC-MS were employed to reveal the possible Z-scheme pathway under the built-in electric field of the p-n heterojunction and photocatalytic removing mechanism of TC and Cr(VI). These results offer a promising idea for the treatment of the combined pollution of antibiotics and heavy metals by a Z-scheme WO3/CoO p-n heterojunction photocatalyst, and have broad application prospects: boosted tetracycline and Cr(VI) simultaneous cleanup over a Z-scheme WO3/CoO p-n heterojunction with a 0D/3D structure under visible light. [ABSTRACT FROM AUTHOR]

Recently, heterojunctions formed between dissimilar semiconducting materials have been received considerable attention as an elementary building block of photodetectors (PDs) due to their enormous potential of tuning the wavelength selectivity from bandgap limited photoresponsivity in a single band to multiband or broadband. In this work, titania (TiO2) nanorods (NRs) with anatase crystalline structures were synthesized using hydrothermal method and spin coated on p-Si to realize Au/TiO2 NRs/p-Si (lateral) and Au/TiO2 NRs/p-Si/Ag (vertical) heterojunction broadband (BB) PDs. The structural and optical parameters of the prepared TiO2 NRs/p-Si heterojunction were studied using XRD, SEM, EDS, XPS and UV–VIS methods. A direct optical bandgap of 3.22 eV was evaluated using Tauc's method for the TiO2 nanorod (NR) films deposited on quartz substrate. XPS data revealed two strong binding energy (BE) peaks at 464.4 eV and 458.7 eV which correspond to core level spectral lines of Ti2p1/2 and Ti2p3/2, respectively, may arise owing to the interaction of Ti–O–Si bonds. The photoresponse parameters of the prepared two types of BB PDs were evaluated and compared using I–V, responsivity and I–T methods. The vertical structure exhibited betterment in transient responses (@-7 V) due to its reverse bias operation compared to the lateral structure which operated in forward bias (@ 10 V). The Au/TiO2 NRs/p-Si/Ag: vertical BB PD device displayed a peak photoresponsivity of 41 μA/W, detectivity of 4.6 × 108 Jones and rise/fall times of 0.36 s/0.45 s, when compared to Au/TiO2 NRs/p-Si lateral device architecture. This work suggests a simple approach for the development of tunable functionality of inorganic n-TiO2 NRs/p-Si heterojunction-based BB PDs (300–1100 nm) to fit the future necessities of the optoelectronic field. [ABSTRACT FROM AUTHOR]

The Bi2O3/Bi2WO6 heterostructures of various compositions are prepared via the surfactant-assisted sol–gel method, which exhibits enhanced and synergistic photocatalytic activity towards the degradation of Rhodamine B (Rh B) using visible light irradiation. Characterization of these heterostructures has been done using X-ray diffraction, microscopic and spectroscopic methods. The 50% tungstate in bismuth oxide (BWO) nanocomposites having band gap of 2.85 eV and an average size of 40–80 nm shows maximum dye removal up to 87% in 4 h compared to pure Bi2O3 and other heterostructures of Bi2O3/Bi2WO6. The reusability studies demonstrate the excellent retention of photocatalytic activity without much loss in activity, implying the stability and efficiency of the prepared catalyst. The degradation of the Rh B dye is modeled mathematically to analyze the interactive effects of the key parameters like the time, amount of catalyst, and dye concentration, and to determine the optimal setting of these parameters to optimize the degradation process using the face-centered Central Composite Design (FC-CCD) of the Response Surface Methodology (RSM) analysis. An accurate full quadratic model has been developed with R2 = 99.41%. The sensitivity of the degradation was evaluated at all levels of the key parameters. At 0.1 g of catalyst amount, it was found that the increment of the catalyst amount would be suitable for improved degradation as compared to allowing more time for the degradation. The maximum degradation was obtained for a dye concentration of 5 ppm, and 0.1 g catalyst for 4 h. [ABSTRACT FROM AUTHOR]

2D organic–inorganic perovskites are an emerging class of materials with great potential for optoelectronics since a wide variety of large functional chromophores can be regularly incorporated. Among this new type of materials, hybrid perovskite systems incorporating strong electron acceptor molecules are considered as a promising approach to designing a new type of functional 2D perovskites for optoelectronics. In this work, a rare example of organic–inorganic 2D perovskite incorporating strong acceptors such as naphthalene diimide (NDI) building blocks between inorganic sheets is presented. This hybrid architecture forms highly air‐stable thin films with a structure consisting of inorganic perovskite monolayers of metal‐halide octahedra separated by bilayers of NDI‐based organic cations. The presence of strong electron‐accepting moieties in this multifunctional donor–acceptor hybrid heterostructure leads to a rare type II heterojunction in which the excitons can be efficiently dissociated via the electron‐transfer process and in which holes and electrons can be easily confined in the inorganic and organic sublayers, respectively. Such an ultimate p–n heterojunction shows improved photoconduction properties with a photocurrent multiplied by ≈40 under white‐light illumination in comparison to a similar 2D perovskite structure containing optically and electrically inert alkyl chains as organic components. [ABSTRACT FROM AUTHOR]

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The 2D MoS2 with superior optoelectronic properties such as high charge mobility and broadband photoresponse has attracted broad research interests in photodetectors (PD). However, due to the atomic thin layer of 2D MoS2, its pure photodetectors usually suffer from inevitable drawbacks such as large dark current, and intrinsically slow response time. Herein, a new organic material BTP‐4F with high mobility is successfully stacked with 2D MoS2 film to form an integrated 2D MoS2/organic P–N heterojunction, facilitating efficient charge transfer as well as significantly suppressed dark current. As a result, the as‐obtained 2D MoS2/organic (PD) has exhibited excellent response and fast response time of 332/274 µs. The analysis validated photogenerated electron transition from this monolayer MoS2 to subsequent BTP‐4F film, whereas the transited electron is originated from the A− exciton of 2D MoS2 by temperature‐dependent photoluminescent analysis. The ultrafast charge transfer time of ≈0.24 ps measured by time‐resolved transient absorption spectrum is beneficial for efficient electron–hole pair separation, greatly contributing to the obtained fast photoresponse time of 332/274 µs. This work can open a promising window to acquire low‐cost and high‐speed (PD). [ABSTRACT FROM AUTHOR]

Fabricating an efficient photocatalyst for solving energy and environmental pollution is challenging, especially using sunlight. Herein, a photocatalyst was developed to degrade plasticizer (Bisphenol A, BPA) and an industrial‐pollutant 2,4‐dinitrophenol (DNP) found in water bodies with sunlight. Several ZnIn2S4/B‐doped g‐C3N4 (ZIS@BCN) heterojunctions were prepared by an ultra‐sonochemical route followed by calcination. HRTEM, MS analysis, EIS, photocurrent, and synergic factor calculations were employed to confirm p‐n heterojunction. The phase purity and optical characteristics of the photocatalysts were determined by XRD, PL, and DRS UV‐Vis spectroscopy. A successful p‐n heterojunction 2 %ZIS@BCN showed better degradation efficiency than pristine ZIS (n‐type) and BCN (p‐type) semiconductors. Moreover, the best photocatalyst (2 % ZIS@BCN) exhibited maximum photo‐degradation of 83 % of BPA and 85 % of DNP under solar light illumination. The degradation pathways and involvement of reactive species were confirmed using LC–MS, trapping experiments, nitroblue‐tetrazolium, and terephthalic acid tests. The superior activity is ascribed to the successful formation of an electrical double layer (EDL) between p‐type BCN and n‐type ZIS, which minimizes the e−‐h+ recombination and thereby increases the visible light utilization efficiency. The work validates the formation of ZIS@BCN p‐n heterojunction, showing solar light‐driven photocatalytic degradation of toxic effluents found in water bodies. [ABSTRACT FROM AUTHOR]

High photoelectrochemical water oxidation efficiency can be achieved through an efficient photogenerated holes transfer pathway. Constructing a photoanode semiconductor heterojunction with close interface contact is an effective tactic to improve the efficiency of photogenerated carrier separation. Here, we reported a novel photoanode p-n junction of Ti:Fe2O3/Cu2O (n-Ti:Fe2O3 and p-Cu2O), Cu2O being obtained by in situ reduction in CuAl-LDH (layered double hydroxides). The Ti:Fe2O3/Cu2O photoanode exhibits a high photocurrent density reaching 1.35 mA/cm2 at 1.23 V vs. RHE is about 1.67 and 50 times higher than the Ti:Fe2O3 and α-Fe2O3 photoanode, respectively. The enhanced PEC activity for the n-Ti:Fe2O3/p-Cu2O photoelectrode is due to the remarkable surface charge separation efficiency (ηsurface 85%) and bulk charge separation efficiency (ηbulk 72%) formed by the p-n junction and the tight interface contact formed by in situ reduction. Moreover, as a cocatalyst, CuAl-LDH can protect the Ti:Fe2O3/Cu2O photoanode and improve its stability to a certain extent. This study provides insight into the manufacturing potential of in situ reduction layered double hydroxides semiconductor for designing highly active photoanodes in the field of photoelectrochemical water oxidation. [ABSTRACT FROM AUTHOR]

The S-scheme photocatalyst system has become increasingly popular in recent years for its ability to efficiently degrade various pollutants, including organic dyes, pesticides, and other harmful substances. This system uses two semiconductor photocatalysts with different bandgap energies, working together in a redox reaction to produce a highly reactive species capable of pollutant breakdown. Here, an S-scheme Ag2WO4/Ag6Si2O7 p-n heterojunction nanocomposite was successfully developed by a coprecipitation method. By decomposing Rhodamine B (RhB) under visible-light irradiation, the photocatalytic activities of Ag6Si2O7/Ag2WO4 showed enhanced photocatalytic degradation performance of organic dyes, especially at a 4% molar ratio of the Ag2WO4-modified Ag6Si2O7 sample, whose degradation rate was 23.7 and 4.65 times those of Ag2WO4 and Ag6Si2O7, respectively. The physical and chemical properties of the samples were determined by identifying the physical structure, chemical element composition, and optical responsiveness. The optimum composite amongst the prepared materials was AgSW-4, achieving the maximum RhB degradation efficiency of 97.5%, which was higher by 60% and 20% than its counterparts Ag6Si2O7 and Ag2WO4, respectively. These results showed that in the nanocomposite structure, Ag6Si2O7 was a p-type semiconductor and Ag2WO4 was an n-type semiconductor. Based on the analysis data, a comprehensive p-n heterojunction S-scheme process was proposed to demonstrate the enhanced photocatalytic performance of the Ag6Si2O7/Ag2WO4 nanocomposite. [ABSTRACT FROM AUTHOR]

An effective p–n heterojunction fabrication strategy of amorphous ZnGa2O4/NiO self‐powered ultraviolet (UV) photodetector is reported to consider both the low‐temperature and band alignment. Owing to the excellent photovoltaic effect, the device exhibits an ultralow dark current of 1.81 pA, a satisfactory response sensitivity of 48.19 mA W−1, a specific detectivity of 1.9 × 1012 Jones, and a high rise/decay speed of 41/22 ms under 255 nm light irradiation at 0 V bias. Compared with previously reported UV photodetectors, the proposed photodetector exhibits a high responsivity of 1.88 A W−1 and an excellent detectivity of 7.1 × 1013 Jones under an applied voltage of −5 V, indicating its ability to detect weak signals. This remarkable photoelectric detection capability is attributed to the strong absorption of UV light by the amorphous ZnGa2O4 and typical type‐II band alignment at the heterojunctions. Moreover, the photodetector continues to function stably without degradation, even after two months without an external power supply. This work not only provides an effective reference for the manufacture of high performance ZnGa2O4‐based UV photodetectors, but also offers the opportunity for practical industrial production and flexible applications. [ABSTRACT FROM AUTHOR]

Deep ultraviolet monitoring is realized via a high crystal quality SnO2 microwire (MW)‐based photodetector (PD). This is then combined with 2D nitrogen‐doped graphene (NGr), conducting polymer polypyrrole (PPy), and an in situ polymerization‐fabricated composite film PPy‐NGr to construct an organic–inorganic p–n heterojunction PD. The long response time brought on by the oxygen adsorption of SnO2 MW is greatly decreased via coating with the aforementioned materials. A defect response is created by the surface dangling bonds of SnO2 MW, which can be effectively suppressed by the PPy. Absorption in the deep ultraviolet region (<240 nm) by PPy results in a blue shift of the response peak of the PPy/SnO2 heterojunction PD compared to that of a single SnO2 PD. The introduction of NGr improves the detection performance by providing a smoother energy band migration to reduce photogenerated carrier recombination and stacking at the potential barrier. The ultrahigh responsivity of PPy‐NGr/SnO2 PD is 4594.25 A W−1 and the detectivity is 6.47 × 1011 Jones, 40 and nine times greater, respectively, than those of a PPy/SnO2 PD under a 5 V reverse bias and 240‐nm light irradiation (18.75 µW cm−2). The novel strategy provides a reference for the future design of high‐performance heterojunction PDs. [ABSTRACT FROM AUTHOR]

Deep ultraviolet monitoring is realized via a high crystal quality SnO2 microwire (MW)‐based photodetector (PD). This is then combined with 2D nitrogen‐doped graphene (NGr), conducting polymer polypyrrole (PPy), and an in situ polymerization‐fabricated composite film PPy‐NGr to construct an organic–inorganic p–n heterojunction PD. The long response time brought on by the oxygen adsorption of SnO2 MW is greatly decreased via coating with the aforementioned materials. A defect response is created by the surface dangling bonds of SnO2 MW, which can be effectively suppressed by the PPy. Absorption in the deep ultraviolet region (<240 nm) by PPy results in a blue shift of the response peak of the PPy/SnO2 heterojunction PD compared to that of a single SnO2 PD. The introduction of NGr improves the detection performance by providing a smoother energy band migration to reduce photogenerated carrier recombination and stacking at the potential barrier. The ultrahigh responsivity of PPy‐NGr/SnO2 PD is 4594.25 A W−1 and the detectivity is 6.47 × 1011 Jones, 40 and nine times greater, respectively, than those of a PPy/SnO2 PD under a 5 V reverse bias and 240‐nm light irradiation (18.75 µW cm−2). The novel strategy provides a reference for the future design of high‐performance heterojunction PDs. [ABSTRACT FROM AUTHOR]

Photocatalysts derived from semiconductor heterojunctions for water splitting have bright prospects in solar energy conversion. Here, a Co3O4@ZIS p-n heterojunction was successfully created by developing two-dimensional ZnIn2S4 on ZIF-67-derived hollow Co3O4 nanocages, realizing efficient spatial separation of the electron-hole pair. Moreover, the black hollow structure of Co3O4 considerably increases the range of light absorption and the light utilization efficiency of the heterojunction avoids the agglomeration of ZnIn2S4 nanosheets and further improves the hydrogen generation rate of the material. The obtained Co3O4(20) @ZIS showed excellent photocatalytic H2 activity of 5.38 mmol g−1·h−1 under simulated solar light, which was seven times more than that of pure ZnIn2S4. Therefore, these kinds of constructions of hollow p-n heterojunctions have a positive prospect in solar energy conversion fields. [ABSTRACT FROM AUTHOR]

Ag2O@g-C3N4 catalysts with p-n heterostructure were prepared by the hydrothermal method. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectric spectroscopy, and UV/visible light spectroscopy. Ag2O nanoparticles were uniformly distributed on the surface of g-C3N4 and a heterostructure was formed. The sample Ag2O@g-C3N4 degraded methylene blue (MB) dye by visible light, which showed that it had good photocatalytic activity. Under the same catalytic conditions, the catalytic efficiency of Ag2O@g-C3N4 is two times higher than that of pure g-C3N4. The improvement in catalytic efficiency is due to the formation of heterostructure between Ag2O and g-C3N4, which greatly reduces the recombination rate of electrons and holes. At the same time, Ag is a good electron trapping agent, which increases the mobility of electrons and holes and inhibits the photoetching of Ag2O. Finally, the photocatalytic principle of Ag2O@ g-C3N4 was analyzed for its excellent photocatalytic performance. [ABSTRACT FROM AUTHOR]

The p-n heterojunction Bi2O3/TiO2 catalysts with different mass ratios of Bi2O3 were prepared by the sol–gel method. Under simulated solar irradiation, the photocatalytic degradation effects of Bi2O3, TiO2, and p-n heterojunction Bi2O3/TiO2 on acid red 18 (AR18) were evaluated. The characterizations show that the diffraction peaks were all anatase phase and Bi2O3 was evenly distributed on the surface of TiO2. With the increase of Bi2O3 content, the band gap of the composites gradually decreased. When the dosage of catalyst (Bi2O3 mass ratio was 10%) was 0.5 g/L and the initial concentration of dye was 50 mg/L, the photocatalytic experiment was carried out under a xenon lamp (500 W), the p-n heterojunction formed by Bi2O3 and TiO2 improved the performance of the photocatalyst and showed good catalytic performance under acidic conditions. Compared with TiO2 and Bi2O3, when the mass ratio of Bi2O3 was 10%, the photocatalytic degradation performance of the material was the best, and the degradation rate of AR18 could reach 99.76% after 210 min illumination. [ABSTRACT FROM AUTHOR]

Solar radiation is a cheap and abundant energy for water remediation, hydrogen generation by water splitting, and CO2 reduction. Supported photocatalysts have to be tuned to the pollutants to be eliminated. Spectral engineering may be a handy tool to increase the efficiency or the selectivity of these. Photonic nanoarchitectures of biological origin with hierarchical organization from nanometers to centimeters are candidates for such applications. We used the blue wing surface of laboratory-reared male Polyommatus icarus butterflies in combination with atomic layer deposition (ALD) of conformal ZnO coating and octahedral Cu2O nanoparticles (NP) to explore the possibilities of engineering the optical and catalytic properties of hybrid photonic nanoarchitectures. The samples were characterized by UV-Vis spectroscopy and optical and scanning electron microscopy. Their photocatalytic performance was benchmarked by comparing the initial decomposition rates of rhodamine B. Cu2O NPs alone or on the butterfly wings, covered by a 5 nm thick layer of ZnO, showed poor performance. Butterfly wings, or ZnO coated butterfly wings with 15 nm ALD layer showed a 3 to 3.5 times enhancement as compared to bare glass. The best performance of almost 4.3 times increase was obtained for the wings conformally coated with 15 nm ZnO, deposited with Cu2O NPs, followed by conformal coating with an additional 5 nm of ZnO by ALD. This enhanced efficiency is associated with slow light effects on the red edge of the reflectance maximum of the photonic nanoarchitectures and with enhanced carrier separation through the n-type ZnO and the p-type Cu2O heterojunction. Properly chosen biologic photonic nanoarchitectures in combination with carefully selected photocatalyst(s) can significantly increase the photodegradation of pollutants in water under visible light illumination. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) has received extensive attention in the field of photoelectrochemical water splitting (PEC‐WS). However, ZnO has a narrow absorption range for visible light, easy recombination of photogenerated electrons and holes, and slow kinetics of surface water oxidation, limiting its further practical application. In this work, a FTO/TiO2/ZnO/NiO photoanode with a micro‐nano structure is built with ZnO as nanosheet clusters, TiO2 as the electron transport layer, and NiO for forming p‐n heterojunction between NiO and ZnO. This photoanode exhibits a photocurrent density of 1.91 mA/cm2 at 1.23 VRHE, which is three times that of the pure ZnO photoanode (0.65 mA/cm2). The detailed mechanism investigations demonstrate that the introduced TiO2 can reduce the interface defects between ZnO and FTO, and Ti doping to ZnO improves the conductivity, which simultaneously reduces the bottom surface and bulk charge recombination. The constructed p‐n heterojunction further significantly increases the carrier transfer efficiency. [ABSTRACT FROM AUTHOR]

Herein, CuS was incorporated with ZnS to form a novel nanocomposite via cation exchange, and the product was then employed for dual application of the colorimetric determination and photocatalytic degradation of tetracycline (TC) in water. The formed p–n heterojunction provided an improved gap width and electron mobility, which could rapidly catalyze H2O2 to produce plenty of •OH, supporting a color conversion with TMB. Meanwhile, the addition of TC could lead to the further enhancement in colorimetric signal, and the distinction level was sensitive to the target amount. Additionally, under light conditions, the p-CuS/n-ZnS could produce •O2−, •OH, and h+ through photocatalysis, and these ions could degrade the TC via oxidation. In the colorimetric determination of TC, the signal responses were obtained within 10 min, and the detection limit was 20.94 nM. The recovery rates were 99% and 106% for the water samples from Ganjiang river. In the photocatalytic degradation, the TC was degraded by 91% within 120 min, which was threefold that of ZnS. Meanwhile, the morphology feature of the p-CuS/n-ZnS remained after multiple uses, suggesting a favorable material stability. This strategy provides application prospects for the monitoring and control of antibiotics in water. [ABSTRACT FROM AUTHOR]

ZnO/NiO heterojunction nanofibers were synthesized by an electrostatic spinning technique in this work. The morphologies, crystal structures, and compositional features of the ZnO/NiO nanofibers were analyzed by SEM, TEM, XRD, and EDS characterization. ZnO/NiO nanofibers with Zn contents of 37.5 at% showed a 46% response to 300-ppm ammonia gas at room temperature (25 ± 1 ℃; 56 ± 3% RH), with fast response and recovery behavior (100 s /25 s). The existence of p-n heterojunctions on the surface of ZnO/NiO nanofibers, as well as surface ionic conduction, improved the response to ammonia gas in a synergistic manner. [ABSTRACT FROM AUTHOR]

Magnetically recyclable visible light photocatalysts for the degradation of critical organic pollutants are an urgent industrial requirement. Nonetheless, one component photocatalysts frequently suffer from photo corrosion and recombination issues. Constructing composites of a photocatalytic magnetic phase with a visible range semiconductor could solve both problems. The current article investigates the visible light photocatalytic effectiveness of starch stabilized Fe3O4/Cu2O nanostructures for photocatalytic degradation of p-nitrophenol (PNP) and methyl orange (MO). A stage-wise co-precipitation protocol was employed to prepare these nanocomposites. Mott-Schottky plots of these nanocomposites exhibited positive and negative slope parts, confirming the formation of a p-n heterojunction. Such a coupling of p-type Cu2O with n-type starch functionalized Fe3O4 resulted in a better photocatalyst with improved photostability. Both PNP and MO degradation followed zero-order kinetics under photocatalytic conditions. The nanocomposites demonstrated appreciably better visible light photocatalytic properties along with excellent recyclability. Schematic representation of the mechanism proposed for explaining the photocatalytic Fenton degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Summary: The Co3O4/ZnIn2S4 p‐n heterojunction photocatalyst was successfully prepared using the block stacked by Co3O4 nanosheets as the carrier. Because the surface of the Co3O4 nano‐block is rough, it is easy to absorb more ZnIn2S4 nanosheets, which leads to the tight coupling of composite Co3O4/ZnIn2S4. In addition, the interaction of the p‐n heterojunction interface accelerates the separation of photogenerated carriers, thus increasing the rate of photocatalytic hydrogen evolution. In the photocatalytic hydrogen evolution test, the composite Co3O4/ZnIn2S4 showed excellent hydrogen evolution performance, and the maximum hydrogen evolution capacity was up to 72.01 μmol, which was about 5.6 times that of pure Co3O4. Under the action of the built‐in electric field, the accumulation of electrons and holes in the ZnIn2S4 conduction band and Co3O4 valence band is accelerated, thus higher separation efficiency is achieved. The addition of various characterizations also confirmed the excellent properties of the composites. This work provides a reference for the construction of photocatalytic heterojunction. [ABSTRACT FROM AUTHOR]

Simultaneous transformation of CO2 and H2O into syngas (CO and H2) using solar power is desirable for industrial applications. Herein, an efficient photocatalyst based on double‐shelled nanoboxes, with an outer shell of hydroxy‐rich nickel cobaltite nanosheets and an inner shell of Cu2S (Cu2S@ROH‐NiCo2O3), is prepared via a multistep templating strategy. The high performance of Cu2S@ROH‐NiCo2O3 (7.1 mmol g−1 h−1 for CO; 2.8 mmol g−1 h−1 for H2) is attributed to the hierarchical hollow geometry and p–n heterojunction to promote light absorption and charge separation. Spectroscopic and theoretical analyses elucidate that the ROH‐NiCo2O3 surface enhances *CO2 adsorption and lowers energy barriers for CO2‐to‐CO. Therefore, modulating the hydroxy contents of ROH‐NiCo2O3 can achieve broad CO/H2 ratios from 0.51 to 1.24. This work offers in‐depth insights into adjustable syngas photosynthesis and generalized concepts of selective heterogeneous CO2 photoreduction beyond cobalt‐based oxides. [ABSTRACT FROM AUTHOR]

Simultaneous transformation of CO2 and H2O into syngas (CO and H2) using solar power is desirable for industrial applications. Herein, an efficient photocatalyst based on double‐shelled nanoboxes, with an outer shell of hydroxy‐rich nickel cobaltite nanosheets and an inner shell of Cu2S (Cu2S@ROH‐NiCo2O3), is prepared via a multistep templating strategy. The high performance of Cu2S@ROH‐NiCo2O3 (7.1 mmol g−1 h−1 for CO; 2.8 mmol g−1 h−1 for H2) is attributed to the hierarchical hollow geometry and p–n heterojunction to promote light absorption and charge separation. Spectroscopic and theoretical analyses elucidate that the ROH‐NiCo2O3 surface enhances *CO2 adsorption and lowers energy barriers for CO2‐to‐CO. Therefore, modulating the hydroxy contents of ROH‐NiCo2O3 can achieve broad CO/H2 ratios from 0.51 to 1.24. This work offers in‐depth insights into adjustable syngas photosynthesis and generalized concepts of selective heterogeneous CO2 photoreduction beyond cobalt‐based oxides. [ABSTRACT FROM AUTHOR]

Constructing heterojunction is an attractive strategy for promoting photoelectrochemical (PEC) performance in water splitting and organic pollutant degradation. Herein, a novel porous BiVO4/Boron-doped Diamond (BiVO4/BDD) heterojunction photoanode containing masses of ultra-micro electrodes was successfully fabricated with an n-type BiVO4 film coated on a p-type BDD substrate by magnetron sputtering (MS). The surface structures of BiVO4 could be adjusted by changing the duration of deposition (Td). The morphologies, phase structures, electronic structures, and chemical compositions of the photoanodes were systematically characterized and analyzed. The best PEC activity with the highest current density of 1.8 mA/cm2 at 1.23 VRHE was achieved when Td was 30 min, and the sample showed the highest degradation efficiency towards tetracycline hydrochloride degradation (TCH) as well. The enhanced PEC performance was ascribed to the excellent charge transport efficiency as well as a lower carrier recombination rate, which benefited from the formation of BiVO4/BDD ultra-micro p-n heterojunction photoelectrodes and the porous structures of BiVO4. These novel photoanodes were expected to be employed in the practical PEC applications of energy regeneration and environmental management in the future. [ABSTRACT FROM AUTHOR]