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A silver phosphate (Ag3PO4)/silver (Ag)/silver halide (AgX, X = Cl, Br, or I) ternary composite photocatalysts were prepared by loading Ag nanoparticles on Ag3PO4 tetrapods followed with in situ halogenation. The interface charge transfer behavior in the Ag3PO4/Ag/AgX nanocomposite was studied, and the photocatalytic performance was also evaluated. The results show that the Ag3PO4/Ag/AgI photocatalyst exhibits higher photocatalytic activity than the other two photocatalysts due to the more matched band structure between AgI and Ag3PO4. An internal electric field (IEF) from Ag3PO4 to AgI is formed at the heterogeneous interface, so the photogenerated electrons at the conduction band of AgI can rapidly transfer to the valence band of Ag3PO4 and recombine with photogenerated holes, which is consistent with the S-scheme charge transfer mechanism. Meanwhile, the photogenerated electrons left at the conduction band of Ag3PO4 can transfer to Ag nanoparticles due to the Schottky junction and react with oxygen to produce •O2–, which is proved to be the main active species in the photocatalytic procedure. This tandem junction modulated between the S-scheme heterojunction and Schottky junction promotes the efficient separation of photogenerated carriers, thus significantly increasing the average PL lifetime of electrons by 2.95 times. Therefore, the Ag3PO4/Ag/AgI photocatalyst exhibits excellent photocatalytic activity for the degradation of methylene blue and norfloxacin. The seven consecutive cyclic tests prove the good stability of the photocatalyst, thus showing the application potential in the field of sewage treatment. [ABSTRACT FROM AUTHOR]

ZnO nanomaterial-based UV photodetectors (UV PDs) have a long response time and poor responsiveness. The adjustable work function and high conductivity of 2D Ti3C2-MXene make it a suitable electrode material for optoelectronic devices. In this work, the MXene/ZnO nanorods Schottky junction hybrid was constructed via spin-coating of 2D Ti3C2-MXene nanosheets deposited on a 1D ZnO nanorods array, increasing the optical absorbance of the UV range. The MXene/ZnO nanorods PD at 368 nm and 5 V bias performs noticeably better with a high on/off ratio of 806, a responsivity of 142.2 mA W–1, and a specific detectivity of 2.03 × 1010 jones, which are, respectively, increased by 14.4, 418, and 4194 times than a pure ZnO nanorods PD,. In particular, the rise time and fall times of the MXene/ZnO nanorods PD at 5 V bias are 12.2 s/3.9 s, which are 31 and 76% faster than those of the ZnO nanorods PD, respectively. Developing 2D MXene/ZnO nanorods PDs provides an alternative strategy to improve the response rate and photoelectrical properties of ZnO nanorods PDs over conventional alloy solutions. [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]

Two-dimensional (2D) materials are increasingly being used as detectors and are gaining popularity due to the advantage of tunability of their electrical and thermal properties. Certain non-centrosymmetric materials exhibit a property known as pyroelectricity, which can be utilized to detect infrared (IR) radiation. On the other hand, the pyroelectric effect can be induced in centrosymmetric materials by making them react to external stimuli that break up their symmetry. Here, we report the pyroelectric behavior of a centrosymmetric 2D SiTe2 by inducing interface polarization in a Schottky junction. For this bulk, SiTe2 was synthesized via induction melting and its 2D counterpart via liquid-phase exfoliation. A pyroelectric photodetector in Au/p-SiTe2/ITO configuration was fabricated. The electrical studies confirm the formation of a Schottky junction. The 2D SiTe2-based pyroelectric detector exhibited a high pyroelectric coefficient of 3.73 mC/m2 K and a good responsivity of 3.9 × 105 Jones. The obtained pyroelectric coefficient using 2D SiTe2 was remarkably superior to that of conventional bulk materials. This enhanced property arises from the combined effect of the two-dimensional nature of the material and the induced interface polarization in the device. We employed density functional theory to support our experimental observations. The performance results suggest that 2D SiTe2 could be a benchmark candidate for ultrafast pyroelectric detectors. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting using semiconductor-based catalysts is a promising avenue to gain H2 fuel from renewable solar energy. Nonetheless, developing earth-abundant and visible-light-responsive photocatalysts for efficient H2 production still remains a huge challenge. In this work, unique two-dimensional hierarchitectures of S-deficient CdS integrated with ultrafine CoP nanocrystals embedding in graphitic N-doped C (CoP-CN) nanosheets are fabricated for the first time. Noticeably, the graphitic CN electron mediator not only enhances the photocatalytic stability of CdS/CoP-CN composites by protecting CoP from external corrosion but also induces the formation of an ohmic junction to boost electron extraction from CdS to CoP efficiently. Meanwhile, the S vacancies in CdS serve as electron traps to further enhance the separation of photogenerated carriers. Such unique CdS/CoP-CN hierarchical hybrid nanosheets exhibited an extraordinary visible-light-induced (λ > 400 nm) photocatalytic H2-evolving performance, delivering a high apparent quantum yield (26.3% at 420 nm) and an excellent H2 generation rate of 54.01 mmol·g–1·h–1, much superior to those of a CdS/CoP Schottky junction, Pt-loaded CdS, and a vast amount of CdS-based photocatalysts ever reported. In addition, the outstanding H2-evolving durability of CdS/CoP-CN composites was verified by cycling and long-term photocatalytic tests. The findings presented here are anticipated to enlighten the rational design and synthesis of highly active photocatalysts with an ohmic junction for application in energy and environment-related domains. [ABSTRACT FROM AUTHOR]

Surface defect engineering and heterojunction fabrication are considered to be effective strategies for modifying semiconductor photocatalysts. In this work, we synthesized a series of defect-rich Ti3C2/BiOIO3 nanocomposites for photocatalytic degradation of methyl orange (MO). The samples were characterized by various techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL). The composite exhibited the best photocatalytic performance toward MO under simulated sunlight, which can degrade 95.2% MO in 0.5 h. The total organic carbon (TOC) analysis was also used to ascertain the mineralization degree of MO. The BiOIO3 light response is widened from UV to the visible light region by generating defect energy levels of I–. At the same time, the oxygen vacancy (OV) as the negative charge attraction center captures the excited electrons in the conduction band and doping level, and Ti3C2 as a cocatalyst transfers electrons. This work provides guidance for designing photocatalysts with high-efficient interfacial charge transfer heterostructures. [ABSTRACT FROM AUTHOR]

Friction at sliding interfaces, even in the atomistically smooth limit, can proceed through many energy dissipation channels, such as phononic and electronic excitation. These processes are often entangled and difficult to distinguish, eliminate, and control, especially in the presence of wear. Structural superlubricity (SSL) is a wear-free state with ultralow friction that closes most of the dissipation channels, except for electronic friction, which raises a critical concern of how to effectively eliminate and control such a channel. In this work, we construct a Schottky junction between a microscale graphite flake and a doped silicon substrate in the SSL state to address the issue and achieve wide-range (by 6×), continuous, and reversible electronic friction tuning by changing the bias voltage. No wear or oxidation at the sliding interfaces was observed, and the ultralow friction coefficient indicated that electronic friction dominated the friction tuning. The mechanism of electronic friction is elucidated by perturbative finite element analysis, which shows that migration of the space-charge region leads to drift and diffusion of charge carriers at Schottky junctions, resulting in energy dissipation.

We report a nontransition-metal chalcogenide Bi2Te3–Aux nanocomposite (NC) architecture by two-step solvothermal synthesis of Bi2Te3 combined with in situ reduction (Kirkendall effect) of HAuCl4 (with concentration of x mM) to obtain nano Schottky junctions with Au nanoclusters on Bi2Te3 nanosheets. The interface of Bi2Te3–Au is analyzed using various microscopic, spectroscopic, and electrical characterizations. The increased Schottky junction density with increased Au loading (x = 0.25–20 mM in solution) resulted in an enhancement of peroxidase activity (POD) by 4.2–9.6 folds, upto x = 5 mM, compared to pure Au nanoclusters. The kinetics, studied by Michaelis–Menten plots, reveal similar activity of the NCs to that of the gold standard horseradish peroxidase (HRP). The binding affinities of tetramethylbenzidine for Bi2Te3–Au0.5 and Bi2Te3–Au5 are found to be 1.57 and 4.9 folds better than that of HRP. The synergistic POD activity enhancement follows the electron-transfer mechanism. A facile H2O2-mediated colorimetric glucose detection is demonstrated by the Bi2Te3–Au0.5 NCs with a limit of detection 0.38 mM. These results show the possibility of converting an inactive nontransition-metal chalcogenide to an active one with distributed nano Schottky junctions with Au nanoclusters showing synergistic POD. The nontransition-metal chalcogenide–noble metal interface may be developed for antioxidant properties, bio-detection, and bio-catalysis. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) biosensors show great potential in biochemical molecular detection due to the advantages of low background noise, high sensitivity, and easy integration. However, the current PEC glucose biosensors are subject to the deficiencies of the relatively large limit of detection, small detectable range of concentration, and requirement of an operation voltage. Herein, we construct an unbiased glucose biosensor both in three- and two-electrode configurations using a glucose oxidase (GOx)-modified Schottky junction comprised of Au nanoparticle (NP)-decorated TiO2-coated Al films. A wide detectable range of concentration (0.3–104 μM) is achieved at relatively zero bias versus the reference electrode in a three-electrode configuration under AM 1.5G illumination along with a fitted sensitivity of 3780 μA mM–1 cm–2 (in the concentration range of 0.3–1.0 μM) and a limit of detection down to 0.05 μM. The photocurrents corresponding to typical interfering substances (e.g., uric acid and ascorbic acid) are less than 10% of that to glucose. Moreover, the constructed sensor achieves almost no attenuation in photocurrent under light ON/OFF circular irradiation for 30 min and shows a photocurrent around 92% of the initial value after 30-day storage in air at room temperature. The satisfactory sensing performance is ascribed to the following three aspects: (1) the optical absorption is enhanced due to the formation of a plane-parallel resonance cavity and the reduced band gap of the TiO2 material, (2) the separation and extraction of the photogenerated carriers are facilitated due to the Al doping and the embedded Schottky junction, and (3) the carrier transfer from the photoelectrode surfaces into the electrolyte is boosted because of the Au NPs and nanostructured GOx decoration. This work provides an alternative route to prepare high-performance and self-powered glucose sensors for diabetes diagnosis. [ABSTRACT FROM AUTHOR]

Self-formation of boron-doped diamond (BDD)-multilayer graphene (MLG) core-shell nanowalls (BDGNWs) via microwave plasma-enhanced chemical vapor deposition is systematically investigated. Here, the incorporation of nitrogen brings out the origin of MLG shells encapsulating the diamond core, resulting in unique sp 3 /sp 2 hybridized frameworks. The evolution mechanism of the nanowall-like morphology with the BDD-MLG core-shell composition is elucidated through a variety of spectroscopic studies. The photocatalytic performance of these core-shell nanowalls is examined by the deterioration of methylene blue (MB) and rhodamine B (RhB) dyes beneath low-power ultraviolet (UV) light irradiation. Starting with 5 ppm dye solutions and employing BDGNWs as the photocatalyst, remarkable degradation efficiencies of 95% for MB within 100 min and 91% for RhB within 220 min are achieved. The effect of varying dye concentrations was also examined. The enhanced photocatalytic activity is driven by carrier photogeneration and mediated by the Schottky junction formed between BDD and MLG, promoting efficient photoinduced charge separation. The stability of the BDGNW photocatalyst is examined, and after five test runs, the photocatalytic behavior for MB and RhB degradation decreases to 87 and 85%, respectively, from initial values of 96 and 91%, demonstrating excellent photostability. These findings underscore the significance of diamond-graphene nanoarchitectures as promising green carbonaceous photocatalysts.

With the development of modern infrared detection systems, military targets are more easily exposed, leading to the increasing risk of high-value targets being detected. Thus, stealth materials are highly desired to protect these targets. Additionally, stealth materials should expand their application scenarios to meet the growing performance requirements of military equipment. In this work, a polyacrylonitrile (PAN)/Al–ZnO/Ag nanofiber composite (PAN/ZAO/Ag) with three functions including infrared protection, antibacterial property, and self-cleaning was prepared by electrospinning, solvothermal, and electroless plating processes. The Schottky junction was formed due to the direct contact between ZAO nanosheets and Ag nanoparticles, leading the materials to possess the characteristic of plasmon resonance absorption of near-infrared light. In the thermal infrared imaging band of 8–14 μm, the infrared emissivity of the fiber was as low as 0.39, effectively blocking the target's thermal radiation. The composite membranes also achieved self-cleaning effect and synergistic antibacterial effect, with the maximum contact angle of 131.5° for water and 100% of antibacterial rate. In summary, this study provided a possibility for multifunctional infrared protective clothing materials to deal with the complex battlefield environment. [ABSTRACT FROM AUTHOR]

Metal-semiconductor junctions play an important role in the development of electronic and optoelectronic devices. A Schottky junction photodetector based on two-dimensional (2D) materials is promising for self-powered photodetection with fast response speed and large signal-to-noise ratio. However, it usually suffers from an uncontrolled Schottky barrier due to the Fermi level pinning effect arising from the interface states. In this work, all-2D Schottky junctions with near-ideal Fermi level depinning are realized, attributed to the high-quality interface between 2D semimetals and semiconductors. We further demonstrate asymmetric diodes based on multilayer graphene/MoS 2 /PtSe 2 with a current rectification ratio exceeding 10 5 and an ideality factor of 1.2. Scanning photocurrent mapping shows that the photocurrent generation mechanism in the heterostructure switches from photovoltaic effect to photogating effect at varying drain biases, indicating both energy conversion and optical sensing are realized in a single device. In the photovoltaic mode, the photodetector is self-powered with a response time smaller than 100 μs under the illumination of a 405 nm laser. In the photogating mode, the photodetector exhibits a high responsivity up to 460 A/W originating from a high photogain. Finally, the photodetector is employed for single-pixel imaging, demonstrating its high-contrast photodetection ability. This work provides insight into the development of high-performance self-powered photodetectors based on 2D Schottky junctions.

Toluene is one of the harmful volatile organic compounds (VOCs) for both human health and environments. Thus, to prevent the hazardous effect of toluene, fast detection at an early stage is needed. CuO shows the merit for a wide range responsivity to VOCs but suffers from small response value, slow response/recovery speeds, and low durability. Herein, we report a facile preparation of CuO/Ti3C2Tx MXene hybrids via electrostatic self-assembly. The CuO nanoparticles (∼7 nm) were uniformly dispersed on the surface and the interlayers of the Ti3C2Tx MXene, forming hybrid heterostructures. The CuO/Ti3C2Tx MXene exhibited the improved toluene gas sensing response (Rg/Ra) of 11.4, which is nearly 5 times higher than that of the pristine CuO nanoparticles (2.3) to 50 ppm of toluene at 250 °C. Due to the different work function (Φ), the Schottky junction was established at the interface of CuO/Ti3C2Tx MXene, acting as a hole trapping region (HTR) at the Ti3C2Tx MXene side. Compared to other hybrid 2D materials such as MoS2 and rGO, which possess a higher work function, the CuO/Ti3C2Tx MXene maintained better toluene sensing performance. Thus, the work function is critical for designing a high sensing performance of hybrid metal oxides/2D materials. The hybridization of CuO with Ti3C2Tx MXene improved not only enhancement of the response time but also the selectivity and the responses (270 s) and recovery times (10 s) compared with those of CuO, due to high conductivity of the metallic phase in Ti3C2Tx MXene. Such excellent performance showed the promising applications of metal oxides/2D hybrid materials for VOCs gas sensing. [ABSTRACT FROM AUTHOR]

The practical efficacy of nanomedicines for treating solid tumors is frequently low, predominantly due to the elevated interstitial pressure within such tumors that obstructs the penetration of nanomedicines. This increased interstitial pressure originates from both liquid and solid stresses related to an undeveloped vascular network and excessive fibroblast proliferation. To specifically resolve the penetration issues of nanomedicines for tumor treatment, this study introduces a holistic "dual-faceted" approach. A treatment platform predicated on the WS 2 /Pt Schottky heterojunction was adopted, and flexocatalysis technology was used to disintegrate tumor interstitial fluids, thus producing oxygen and reactive oxygen species and effectively mitigating the interstitial fluid pressure. The chemotherapeutic agent curcumin was incorporated to further suppress the activity of cancer-associated fibroblasts, minimize collagen deposition in the extracellular matrix, and alleviate solid stress. Nanomedicines achieve homologous targeting by enveloping the tumor cell membrane. It was found that this multidimensional strategy not only alleviated the high-pressure milieu of the tumor interstitium─which enhanced the efficiency of nanomedicine delivery─but also triggered tumor cell apoptosis via the generated reactive oxygen species and modulated the tumor microenvironment. This, in turn, amplified immune responses, substantially optimizing the therapeutic impacts of nanomedicines.

Light-emitting diodes (LED) currently play a key role in solid- state illumination and displays. Using nanotechnology, more advanced and functional LEDs have been developed. Here, a violet-light-emitting device with stroke growth of ZnO nanorods and a metal/n-ZnO/GaN structure was developed for nanostroke. The device has strong violet light, overwhelming monochromaticity, 400 nm wavelength, a full width at half- maximum (fwhm) of ~14 nm, and it displays character edges at ~400 nm resolution using electroluminescence. The new device has strong potential applications in micro-LED and nonmask near-field lithography. [ABSTRACT FROM AUTHOR]

The Schottky junction is an important unit in electronics and optoelectronics. However, its properties greatly degrade with device miniaturization. The fast development of circuits has fueled a rapid growth in the study of two-dimensional (2D) crystals, which may lead to breakthroughs in the semiconductor industry. Here we report a floating-gate manipulated nonvolatile ambipolar Schottky junction memory from stacked all-2D layers of graphene-BP/h-BN/graphene (BP, black phosphorus; h-BN, hexagonal boron nitride) in a designed floating-gate field-effect Schottky barrier transistor configuration. By manipulating the voltage pulse applied to the control gate, the device exhibits ambipolar characteristics and can be tuned to act as graphene-p-BP or graphene-n-BP junctions with reverse rectification behavior. Moreover, the junction exhibits good storability properties of more than 10 years and is also programmable. On the basis of these characteristics, we further demonstrate the application of the device to dual-mode nonvolatile Schottky junction memories, memory inverter circuits, and logic rectifiers. [ABSTRACT FROM AUTHOR]

Self-powered operation and multifunctionality have significantly oriented the development of photodetectors (PDs), which could be realized through nanoarchitecture construction and energy band structure design. Herein, a self-powered wavelength-dependent dual-polarity response PD based on (CdS@PEDOT:PSS@Au) sandwich-structured core-shell nanorod arrays (NRAs) is proposed. The synthesis approach of this three-layer heterostructure consists of a hydrothermal reaction, spin coating, and thermal evaporation. The n -CdS/ p -PEDOT:PSS junction and the PEDOT:PSS/Au Schottky junction at the interfaces provide two photocurrent driving forces in opposite directions, and their contribution to the net photocurrent is controlled by the incident light wavelength due to the different light absorption ranges of the CdS core and the PEDOT:PSS shell. As a result, the polarity of the photocurrent switches from negative to positive as the wavelength increases. In addition, the response speed of negative photocurrents (∼10 ms) is faster than that of positive photocurrents (∼100 ms), which is consistent with the underlying mechanism of the dual-polarity response. Furthermore, color discrimination and imaging capabilities are demonstrated by deploying the PDs as sensing pixels and recognizing green and red patterns. The sandwich-structured core-shell NRA heterojunction system introduces a novel idea for dual-polarity response PDs.

Tribovoltaic devices are attracting increasing attention as motion-based energy harvesters due to the high local current densities that can be generated. However, while these tribovoltaic devices are being developed, debate remains surrounding their fundamental mechanism. Here, we fabricate thin films from one of the world's most common oxides, TiO 2 , and compare the tribovoltaic performance under contact with metals of varying work functions, contact areas, and applied pressure. The resultant current density shows little correlation with the work function of the contact metal and a strong correlation with the contact area. Considering other effects at the metal-semiconductor interface, the thermoelectric coefficients of different metals were calculated, which showed a clear correlation with the tribovoltaic current density. On the microscale, molybdenum showed the highest current density of 192 mA cm -2 . This work shows the need to consider a variety of mechanisms to understand the tribovoltaic effect and design future exemplar tribovoltaic devices.

Defect engineering in perovskite thin films has attracted extensive attention recently due to the films' atomic-scale modification, allowing for remarkable flexibility to design novel nanostructures for next generation nanodevices. However, the defect-assisted three-dimensional nanostructures in thin film matrices usually has large misfit strain and thus causes unstable thin film structures. In contrast, defect-assisted one- or two-dimensional nanostructures embedded in thin films can sustain large misfit strains without relaxation, which make them suitable for defect engineering in perovskite thin films. Here, we reported the fabrication and characterization of edge-type misfit dislocation-assisted two-dimensional BiMnO x nanochannels embedded in SrTiO 3 /La 0.7 Sr 0.3 MnO 3 /TbScO 3 perovskite thin films. The nanochannels are epitaxially grown from the surrounding films without noticeable misfit strain. Diode-like current rectification was spatially observed at nanochannels due to the formation of Schottky junctions between BiMnO x nanochannels and conducting La 0.7 Sr 0.3 MnO 3 thin films. Such atomically scaled heterostructures constitute more flexible ultimate functional units for nanoscale electronic devices.

For semimetal nanowires with diameters on the order of 10 nm, a semimetal-to-semiconductor transition is observed due to quantum confinement effects. Quantum confinement in a semimetal lifts the degeneracy of the conduction and valence bands in a "zero" gap semimetal or shifts energy levels with a "negative" overlap to form conduction and valence bands. For semimetal nanowires with diameters less than 10 nm, the band gap energy can be significantly larger than the thermal energy at room temperature resulting in a new class of semiconductors suitable for nanoelectronics. As a nanowire's diameter is reduced, its surface-to-volume ratio increases rapidly leading to an increased impact of surface chemistry on its electronic structure. Energy level shifts to states in the vicinity of the Fermi energy with varying surface electronegativity are shown to be comparable in magnitude to quantum confinement effects arising in nanowires with diameters of a few nanometer; these two effects can counteract one another leading to semimetallic behavior at nanowire cross sections at which confinement effects would otherwise dominate. Abruptly changing the surface terminating species along the length of a nanowire can lead to an abrupt change in the surface electronegativity. This can result in the formation of a semimetal-semiconductor junction within a monomaterial nanowire without impurity doping nor requiring the formation of a heterojunction. Using density functional theory in tandem with a Green's function approach to determine electronic structure and charge transport, respectively, current rectification is calculated for such a junction. Current rectification ratios of the order of 103-105 are predicted at applied biases as low as 300 mV. It is concluded that rectification can be achieved at essentially molecular length scales with conventional biasing, while rivaling the performance of macroscopic semiconductor diodes. [ABSTRACT FROM AUTHOR]

Vertical heterostructures of van der Waals materials enable new pathways to tune charge and energy transport characteristics in nanoscale systems. We propose that graphene Schottky junctions can host a special kind of photoresponse that is characterized by strongly coupled heat and charge flows that run vertically out of the graphene plane. This regime can be accessed when vertical energy transport mediated by thermionic emission of hot carriers overwhelms electron-lattice cooling as well as lateral diffusive energy transport. As such, the power pumped into the system is efficiently extracted across the entire graphene active area via thermionic emission of hot carriers into a semiconductor material. Experimental signatures of this regime include a large and tunable internal responsivity R with a nonmonotonic temperature dependence. In particular, R peaks at electronic temperatures on the order of the Schottky barrier potential ϕ and has a large upper limit R e/ϕ (e/ϕ = 10 A/W when ϕ = 100 meV). Our proposal opens up new approaches for engineering the photoresponse in optically active graphene heterostructures. [ABSTRACT FROM AUTHOR]

Photocatalytic water cracking hydrogen (H 2 ) production is a promising clean energy production technology. Therefore, a ternary CdS@Nb 2 O 5 /Nb 2 C T x (MXene) heterojunction with hierarchical structure was designed to promote photocatalytic H 2 evolution. When Na 2 S/Na 2 SO 3 and lactic acid were used as sacrificial agents, the hydrogen evolution reaction (HER) rates of the optimized photocatalyst were 1501.7 and 2715.8 μmol g -1 , with 12.4% and 26.1% apparent quantum efficiencies (AQE) at 420 nm, respectively. Its HER performance was 10.9-fold higher than that of pure CdS and remained 87% activity after five rounds of cycle tests. Such an enhancement stems from the excellent light absorption properties, tight interfacial contact, fast charge transfer channel, and sufficient active sites. Mechanism analysis demonstrates that S-scheme and Schottky junction synchronous regulation boost hierarchical CdS@Nb -1 , with 12.4% and 26.1% apparent quantum efficiencies (AQE) at 420 nm, respectively. Its HER performance was 10.9-fold higher than that of pure CdS and remained 87% activity after five rounds of cycle tests. Such an enhancement stems from the excellent light absorption properties, tight interfacial contact, fast charge transfer channel, and sufficient active sites. Mechanism analysis demonstrates that S-scheme and Schottky junction synchronous regulation boost hierarchical CdS@Nb 2 O 5 /Nb 2 C T x for photocatalytic H 2 production. This work creates possibilities for manufacturing Nb-based MXene photocatalysts for converting solar energy and other applications.

Borophene has drawn tremendous attention in the past decade for a wide range of potential applications owing to its unique structural, optical, and electronic properties. However, applications of borophene toward next-generation nanodevices are mostly theoretical predictions, while experimental realization is still lacking due to rapid oxidation of intrinsic borophene in an air environment. Here, we have successfully prepared structurally stable and transferrable few-layer β 12 -borophane on copper foils by a typical two-zone chemical vapor deposition method, where bis(triphenylphosphine)copper tetrahydroborate was used as the boron source in a hydrogen-rich atmosphere to stabilize its structure through hydrogenation. The crystal structure of the as-prepared β 12 -borophane is in good agreement with previous reports. A fabricated photodetector based on β 12 -borophane-silicon ( n -type) Schottky junction shows good photoelectric responses to light excitations in a wide wavelength range from 365 to 850 nm. Especially, the photodetector exhibits a good photoresponsivity of around 0.48 A W -1 , a high specific detectivity of 4.39 × 10 11 jones, a high external quantum efficiency of 162%, and short response and recovery times of 115 and 121 ms under an ultraviolet light with the wavelength of 365 nm at a reverse bias of 5 V. The results show great potential applications of borophane in next-generation nanophotonic and nanoelectronic devices.

We demonstrate that the electrical conductivity of metal/semiconductor oxide heterojunctions can be increased over 7 orders of magnitude by inserting an ultrathin layer of LaAlO3. This counterintuitive result, that an interfacial barrier can be driven transparent by inserting a wide-gap insulator, arises from the large internal electric field between the two polar LaAlO3 surfaces. This field modifies the effective band offset in the device, highlighting the ability to design the electrostatic boundary conditions with atomic precision. [ABSTRACT FROM AUTHOR]

Gas species and concentrations of human-exhaled breath correlate with health, wherein disease markers contain volatile organic compounds (VOCs) of concentrations in parts per billion. It is expected that a gas-sensing strategy possesses a gas specificity and detection limit in the parts per trillion (ppt) range; however, it is still a challenge. This investigation has exploited the Schottky junction of gas sensors for detecting the reactance signal of ppt VOC, aiming for a specific and rapid detection toward disease marker acetone. In this new sensing paradigm, formed by the engineered energy band between metal-semiconductor contact, the Schottky junction is accessed to specific modulation of different adsorbate dopings and the corresponding reactance signal is measured. Regarding the detection toward ppt concentration of acetone, this sensing paradigm possesses rapid (∼100 s) and room-temperature response, molecular specificity, and 34 ppt of detection limit. The proposed detection paradigm is demonstrated to show a high feasibility toward detection of disease marker acetone.

The deployment of two-dimensional (2D) materials for solar energy conversion requires scalable large-area devices. Here, we present the design, modeling, fabrication, and characterization of monolayer MoS 2 -based lateral Schottky-junction photovoltaic (PV) devices grown by using chemical vapor deposition (CVD). The device design consists of asymmetric Ti and Pt metal contacts with a work function offset to enable charge separation. These early stage devices show repeatable performance under 1 sun illumination, with V OC of 160 mV, J SC of 0.01 mA/cm 2 , power conversion efficiency of 0.0005%, and specific power of 1.58 kW/kg. An optoelectronic model for this device is developed and validated with experimental results. This model is used to understand loss mechanisms and project optimized device designs. The model predicts that a 2D PV device with ∼70 kW/kg of specific power can be achieved with minimum optimization to the current devices. By increasing the thickness of the absorber layer, we can achieve even higher performance devices. Finally, a 25 mm 2 area solar cell made with a 0.65 nm thick MoS 2 monolayer is demonstrated, showing V OC of 210 mV under 1 sun illumination. This is the first demonstration of a large-area PV device made with CVD-grown scalable 2D materials.

Photocatalysis presents a feasible option to control low-concentration NO emissions from industrial burning facilities, and increasing excitons in quantity and improving surface activity are the crucial issues to be solved. Plasmonic silver with the orientation of the (111) plane is uniformly distributed on the Ti-O termination of the SrTiO 3 (STO) (100) plane (major). The NO conversion rate has a sixfold increment compared to pristine STO. Meanwhile, the toxic NO 2 had a significant decline in the absence of water. This high performance could be attributed to the unique property of the localized surface plasmonic resonance of silver particles, which increases the optical response range of the catalyst. Meanwhile, the formation of a Schottky junction could promote the charge separation and enhance the lifetime of excitons via the electron transfer from silver particles to STO. More importantly, the Ag-O bond of the heterojunction increases the charge density of adjacent Ti, preferring to bond with the antibonding orbital electron of adsorbed molecules, which offers a favorable channel for the NO adsorption and activation of reactive oxidation species.

In this study, we present a wavelength sensor that is capable of distinguishing the spectrum in the range from ultraviolet (UV) to near-infrared (NIR) light. The filterless device is composed of two horizontally stacking PdSe 2 /20 μm Si/PdSe 2 heterojunction photodetectors with a photovoltaic (PV) behavior, which makes it possible for the device to work at 0 bias voltage. Due to the relatively small thickness of Si and the wavelength-dependent absorption coefficient, the two PdSe 2 /20 μm Si/PdSe 2 photodetectors according to theoretical simulation display a sharp contrast in distribution of the photoabsorption rate. As a result, the photocurrents of both photodetectors evolve in completely different ways with increasing wavelengths, leading to a monotonic decrease in the photocurrent ratio from 6800 to 22 when the wavelength gradually increases from 265 to 1050 nm. The corresponding relationship between both the photocurrent ratio and wavelength can be easily described by the monotonic function, which can help to precisely determine the wavelength in the range from 265 to 1050 nm, with an average relative error less than ±1.6%. It is also revealed that by slightly revising the monotonic function, the wavelength in other different temperatures can also be estimated.

To meet the fast-growing need for broad applications in remote sensing, novel optoelectronic devices with high detectivity in full bands and room temperature operation are urgently desired. This paper reports our progress in developing a specially designed photovoltaic detector by integrating a monolayer graphene onto a silicon-based nanopillar array standing on a p-n junction. Optoelectronic measurements of the fabricated detectors show that the monolayer graphene plays a critical role in device performance. Compared with the one without the graphene covering, the new device demonstrates significant improvements in the specific detectivity of 1.43 × 10 13 Jones and the responsivity exceeding ∼10 6 V/W with a reduced leakage current corresponding to a quantum efficiency of 74.8% at 860 nm wavelength. Moreover, such sensing performance remained unaffected over the entire band from 450 to 1100 nm at room temperature, which is suitable for broadband imaging applications.

Engineering of the interface for tuning the structural, functional, and electronic properties of materials via the formation of heterostructure composites exhibits immense potential in the current research scenario. This study reports a novel ternary composite synthesized by decoration of zero-dimensional Pd nanoparticles (NPs) and two-dimensional (2D) graphite oxide (GO) sheets in the UiO-66 metal-organic framework (MOF). A mixed matrix membrane was fabricated by incorporating this composite in the SPEEK polymer matrix, which exhibited higher selectivity compared to commercial Nafion 117. The synthesized composite and fabricated membranes were thoroughly characterized in terms of their chemical structures, microstructural morphologies, physicochemical, thermal, photo-electrochemical, and optical properties, ion-exchange capacity, proton conductivity, and methanol permeability. As per our knowledge, this is the first study which explores the effect of noble metal NPs and carbon 2D material simultaneously on the electronic structure of the MOF, resulting in improved selectivity. The electron-accepting nature of GO and surface plasmon resonance effect of Pd alter the energy band positions and scavenge the electrons, improving the proton conduction of the composite. The introduction of oxygen vacancies in lattice leads to efficient charge separation. The formation of a Schottky junction results in the localized electric field effect due to electron density fluctuation which aids in ion transport. The current study opens up a new route to overcome the major challenge associated with direct methanol fuel cells (DMFCs), that is, high/low methanol crossover by improving the proton conduction.

Developing high-performance dielectric absorbers, low filler loading, and a broad absorption band remains a great challenge for wireless data communication systems, household appliances, local area network, and so on. Herein, we report a facile green method to design and fabricate a copper-coated tin/reduced graphene oxide (Cu@Sn/rGO) composites with a heterojunction obtained by modifying a Schottky junction. The unique heterojunction can enable an appropriate balance between impedance and strong loss capacity. Meanwhile, it can not only promote the carrier migration but also obtain the rich interfaces. Consequently, a Cu@Sn/rGO composite with a heterojunction exhibits superior absorption intensity, far surpassing that of other absorbing materials reported. With a weight content of only 5 wt %, the maximum absorptivity reaches -49.19 dB at 6.08 GHz, and an effective absorption bandwidth (RL < -10 dB) of 13.94 GHz is achieved when the absorber's thickness ranges from 1.7 to 5.5 mm. This study provides new insights into the design and synthesis of a novel microwave absorption material with lightweight, smaller filler loading, and strong reflection loss.

Cu/TiO 2 is a well-known photocatalyst for the photocatalytic transformation of CO 2 into methane. The formation of C 2+ products such as ethane and ethanol rather than methane is more interesting due to their higher energy density and economic value, but the formation of C-C bonds is currently a major challenge in CO 2 photoreduction. In this context, we report the dominant formation of a C 2 product, namely, ethane, from the gas-phase photoreduction of CO 2 using TiO 2 nanotube arrays (TNTAs) decorated with large-sized (80-200 nm) Ag and Cu nanoparticles without the use of a sacrificial agent or hole scavenger. Isotope-labeled mass spectrometry was used to verify the origin and identity of the reaction products. Under 2 h AM1.5G 1-sun illumination, the total rate of hydrocarbon production (methane + ethane) was highest for AgCu-TNTA with a total C x H 2 x +2 rate of 23.88 μmol g -1 h -1 . Under identical conditions, the C x H 2 x +2 production rates for Ag-TNTA and Cu-TNTA were 6.54 and 1.39 μmol g -1 h -1 , respectively. The ethane selectivity was the highest for AgCu-TNTA with 60.7%, while the ethane selectivity was found to be 15.9 and 10% for the Ag-TNTA and Cu-TNTA, respectively. Adjacent adsorption sites in our photocatalyst develop an asymmetric charge distribution due to quadrupole resonances in large metal nanoparticles and multipole resonances in Ag-Cu heterodimers. Such an asymmetric charge distribution decreases adsorbate-adsorbate repulsion and facilitates C-C coupling of reaction intermediates, which otherwise occurs poorly in TNTAs decorated with small metal nanoparticles.

Environment-adaptable photonic-electronic-coupled devices can help overcome major challenges related to the extraction of highly specific angular information, such as human visual perception. However, a true implementation of such a device has rarely been investigated thus far. Herein, we provide an approach and demonstrate a proof-of-concept solid-state semiconductor-based highly transparent, optical-electrical-coupled, self-adaptive angular visual perception system that can fulfill the versatile criteria of the human vision system. Specifically, all of the primitive functions of visual perception, such as broad angular sensing, processing, and manifold memory storage, are demonstrated and comodulated using optical and electric pulses. This development represents an essential step forward in the fabrication of an environment-adaptable artificial angular perception framework with deep implications in the fields of optoelectronics, artificial eyes, and memory storage applications.

Halide perovskites are promising optoelectronic semiconductors. For applications in solid-state detectors that operate in low photon flux counting mode, blocking interfaces are essential to minimize the dark current noise. Here, we investigate the interface between methylammonium lead tri-iodide (MAPbI 3 ) single crystals and commonly used high and low work function metals to achieve photon counting capabilities in a solid-state detector. Using scanning photocurrent microscopy, we observe a large Schottky barrier at the MAPbI 3 /Pb interface, which efficiently blocks dark current. Moreover, the shape of the photocurrent profile indicates that the MAPbI 3 single-crystal surface has a deep fermi level close to that of Au. Rationalized by first-principle calculations, we attribute this observation to the defects due to excess iodine on the surface underpinning emergence of deep band-edge states. The photocurrent decay profile yields a charge carrier diffusion length of 10-25 μm. Using this knowledge, we demonstrate a single-crystal MAPbI 3 detector that can count single γ-ray photons by producing sharp electrical pulses with a fast rise time of <2 μs. Our study indicates that the interface plays a crucial role in solid-state detectors operating in photon counting mode.

Dual-ion electrolytes with oxygen ion and proton-conducting properties are among the innovative solid oxide electrolytes, which exhibit a low Ohmic resistance at temperatures below 550 °C. BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ with a perovskite-phase cathode has demonstrated efficient triple-charge conduction (H + /O 2- /e - ) in a high-performance low-temperature solid oxide fuel cell (LT-SOFC). Here, we designed another type of triple-charge conducting perovskite oxide based on Ba 0.5 Sr 0.5 Co 0.1 Fe 0.7 Zr 0.1 Y 0.1 O 3-δ (BSCFZY), which formed a heterostructure with ionic conductor Ca 0.04 Ce 0.80 Sm 0.16 O 2-δ (SCDC), showing both a high ionic conductivity of 0.22 S cm -1 and an excellent power output of 900 mW cm -2 in a hybrid-ion LT-SOFC. In addition to demonstrating that a heterostructure BSCFZY-SCDC can be a good functional electrolyte, the existence of hybrid H + /O 2- conducting species in BSCFZY-SCDC was confirmed. The heterointerface formation between BSCFZY and SCDC can be explained by energy band alignment, which was verified through UV-vis spectroscopy and UV photoelectron spectroscopy (UPS). The interface may help in providing a pathway to enhance the ionic conductivities and to avoid short-circuiting. Various characterization techniques are used to probe the electrochemical and physical properties of the material containing dual-ion characteristics. The results indicate that the triple-charge conducting electrolyte is a potential candidate to further reduce the operating temperature of SOFC while simultaneously maintaining high performance.

Rectifying semiconductor junctions are crucial to electronic devices. They convert alternating current into a direct one by allowing unidirectional charge flows. Analogous to the current-flow rectification for itinerary electrons, here, a polar rectification that is based on the localized oxygen vacancies (OVs) in a Ti/fatigued-SrTiO 3 (fSTO) Schottky junction is first demonstrated. The fSTO with OVs is produced by an electrodegradation process. The different movabilities of localized OVs and itinerary electrons in the fSTO yield a unidirectional electric polarization at the interface of the junction under the coaction of external and built-in electric fields. Moreover, the fSTO displays a pre-ferroelectric state located between paraelectric and ferroelectric phases. The pre-ferroelectric state has three sub-states and can be easily driven into a ferroelectric state by an external electric field. These observations open up opportunities for potential polar devices and may underpin many useful polar-triggered electronic phenomena.

Engineering tunable graphene-semiconductor interfaces while simultaneously preserving the superior properties of graphene is critical to graphene-based devices for electronic, optoelectronic, biomedical, and photoelectrochemical applications. Here, we demonstrate this challenge can be surmounted by constructing an interesting atomic Schottky junction via epitaxial growth of high-quality and uniform graphene on cubic SiC (3C-SiC). By tailoring the graphene layers, the junction structure described herein exhibits an atomic-scale tunable Schottky junction with an inherent built-in electric field, making it a perfect prototype to systematically comprehend interfacial electronic properties and transport mechanisms. As a proof-of-concept study, the atomic-scale-tuned Schottky junction is demonstrated to promote both the separation and transport of charge carriers in a typical photoelectrochemical system for solar-to-fuel conversion under low bias. Simultaneously, the as-grown monolayer graphene with an extremely high conductivity protects the surface of 3C-SiC from photocorrosion and energetically delivers charge carriers to the loaded cocatalyst, achieving a synergetic enhancement of the catalytic stability and efficiency.

Two-dimensional (2D) Mo 2 C, as a new member of transition metal carbides, has many intriguing properties and potential applications in superconductors and electronic devices. The thermal stability of 2D materials is essential for the performance of the related devices, especially the ones with a vertical heterostructure. However, rare reports have demonstrated the thermal stability of Mo 2 C and the effects of thermal stability on its performance. Here, we propose a facile and controllable method to directly oxidize Mo 2 C to MoO x , forming a MoO x /Mo 2 C heterostructure. During the oxidization process, an in situ technique is employed to uncover the transformation and thermal stability of the Mo 2 C. The chemical vapor deposition Mo 2 C shows high structural stability below 550 °C in Ar or below 350 °C in O 2 , which demonstrates the high thermal stability and antioxidation of the Mo 2 C film. The metallic Mo 2 C is gradually oxidized to semiconducting MoO x as the temperature increases above 350 °C. The oxidization rate can be easily controlled by adjusting the oxidation temperature and time. Further, the obtained MoO x /Mo 2 C vertical hybrid structure shows obvious Schottky junction behaviors, strongly indicating the perfect interfacial contact between the component layers. This work offers a new strategy for the controllable fabrication of high-quality 2D heterostructures.

Due to the complexity of harmful wastewater components, environmental and multifunctional materials are required for sewage purification. In this paper, a novel kidney-bean-skin-like hydrophilic porous polyacrylonitrile/reduced graphene oxide- g -poly(amidoxime)-loaded Ag + (H-PPAN/rGO- g -PAO@Ag + /Ag) composite nanofiber membrane was fabricated by combining electrospinning and hydrolysis methods. The spinning solution was pumped at a rate of 0.4 mL/h with the voltage set at a constant value of 23 kV. Then, some of the -CN groups switched to hydrophilic -COOH groups via a hydrolysis method, which acts as a linker of GO- g -PAN, Ag + , and the polyacrylonitrile (PAN) matrix. A further step of chelation and thermal treatment were used for generating Schottky junctions between rGO- g -PAO@Ag + and Ag. After five-cycle tests, it exhibited outstanding mechanical properties ensuring the filtration and purification performance of the H-PPAN/rGO- g -PAO@Ag + /Ag composite nanofiber membrane (i.e., the tensile strength was still 7.21 MPa, and the elongation was 61.53%) for simulated wastewater. The methods of thermal treatment and high-pressure Hg lamp irradiation promoted the reduction of GO to rGO and Ag + to Ag particles, which endows the final product H-PPAN/rGO- g -PAO@Ag + /Ag with excellent photocatalytic and bactericidal properties. Its catalytic efficiency for dyes benzoic acid (BA), Rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) was up to 99.8, 98, 95, and 91%. The antibacterial rate was 100% against Escherichia coli and 99% against Staphylococcus aureus . More importantly, the photocatalytic and antibacterial PAN-based nanofiber membrane can be simply scaled up, which provides the membrane with great potential in highly efficient wastewater treatment and augmenting water supply.

Graphene (Gr) presents promising applications in regulating the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Light illumination is regarded as a spatiotemporally controllable, easily applicable, and noninvasive mean to modulate material responses. Herein, Gr-transferred silicon (Gr/Si) with a Schottky junction is utilized to evaluate the visible-light-promoted osteogenic differentiation of BMSCs. Under light illumination, light-induced charges, owing to the formation of the Schottky junction at the interface of Gr and Si, accumulated on the surface and then changed the surface potential of Gr/Si. The Schottky junction and surface potential at the interface of Gr and Si was measured by photovoltaic test and scanning Kelvin probe microscopy. Alkaline phosphatase (ALP) activity and quantitative real-time polymerase chain reaction (PCR) measurement showed that such variations of surface improved the osteogenic differentiation of BMSCs, and the activation of the voltage-gated calcium channels through surface potential and accumulation of cytosolic Ca 2+ could be the reason. Moreover, X-ray photoelectron spectroscopy characterization showed that surface charge could also affect BMSCs differentiation through the promotion or inhibition of the adsorption of osteogenic growth factors. Such light-promoted osteogenic differentiation of BMSCs on Gr/Si may have huge potential for biomedical materials or devices for bone regeneration application.

A Schottky barrier is a double-edged sword in electronic and optoelectronic devices, especially devices based on two-dimensional materials. It may restrict the carrier transport in devices, but it can also realize multifunctional devices by architecture design. We designed a simple but novel device structure based on theWSe 2 -Cr Schottky junction with an asymmetric Schottky contact area of the source and drain. A significant rectification ratio over 10 5 and multiple rectifying states (e.g., full pass, forward pass, off, and backward pass) were achieved in the single Schottky junction tuned by gate voltage. Furthermore, switching characteristic, rectification characteristic, and amplitude of a sin wave can be effectively modulated by the electrical field or light illumination in a signal process circuit based on the WSe 2 -Cr Schottky junction. The highly tunable Schottky junction working as a multimode signal processor unit has great potential in future optoelectronic-integrated chips.

We report on the investigation of the Schottky barrier (SB) formed at the junction between a metal-free graphene monolayer and Ge semiconductor substrate in the as-grown epitaxial graphene/Ge(100) system. In order to preserve the heterojunction properties, we defined submicron size graphene/Ge junctions using the scanning probe microscopy lithography in the local oxidation configuration, a low-invasive processing approach capable of inducing spatially controlled electrical separations among tiny graphene regions. Characteristic junction parameters were estimated from I - V curves obtained using conductive-atomic force microscopy. The current-voltage characteristics showed a p-type Schottky contact behavior, ascribed to the n-type to p-type conversion of the entire Ge substrate due to the formation of a large density of acceptor defects during the graphene growth process. We estimated, for the first time, the energy barrier height in the as-grown graphene/Ge Schottky junction (φ B ≈ 0.45 eV) indicating an n-type doping of the graphene layer with a Fermi level ≈ 0.15 eV above the Dirac point. The SB devices showed ideality factor values around 1.5 pointing to the high quality of the heterojunctions.

A proof-of-concept strategy for significant enhancement of hydrogen evolution reaction (HER) performance of transition metals via construction of a metal/semiconductor Schottky junction is presented. The decoration of low-cost commercial TiO 2 nanoparticles on the surface of microscale Co dendrites causes a significant charge transfer across the Co/TiO 2 Schottky interface and enhances the local electron density at the Co surface, confirmed by X-ray photoelectron spectroscopy results and density functional theory calculations. The Co/TiO 2 Schottky catalyst displays superior HER activity with a turnover frequency of 0.052 s -1 and an exchange current density of 79 μA cm -2 , which are about 4.3 and 4.0 times greater than that of pristine Co, respectively. Moreover, the Co/TiO 2 Schottky catalyst displays excellent electrochemical durability for long-term operation in both alkaline solution and high saline solution. Theoretical calculations suggest that the Schottky junction plays an important role to optimize hydrogen adsorption free energy (Δ G H* Schottky catalyst. This study of modulating the electronic structure of the catalysts via the Schottky junction could provide valuable insights for designing and synthesizing low-cost, high-performance electrocatalysts.2 Schottky catalyst. This study of modulating the electronic structure of the catalysts via the Schottky junction could provide valuable insights for designing and synthesizing low-cost, high-performance electrocatalysts.

Single-layer fuel cells (SLFCs) based on mixed semiconductors and ionic conductors demonstrate  simplified material preparation and fabrication procedure and possess high performance potentially. However, the operational stability and principle of SLFCs have not yet been convinced of either commercialization or fundamental interests. We hereby report on the employment of a perovskite oxide-based phase-structured redox-stable semiconductor prior to determining a possible solution that improves the durability of the SLFC. Feasible working principles are established and an in-depth understanding of the short-circuit-free phenomenon in SLFCs with the mixed ionic and electronic conductors is provided. Additionally, a smart material design and cell structure processing are also proposed. An extended nonstop testing period of up to 2 days confirms the project feasibility and improved durability of the SLFCs, achieved by replacing the unstable lithiated oxide phase with redox-stable perovskite oxide, though the electrochemical performance is sacrificed. The precipitated metal/alloy nanoparticle on perovskite oxide not only improves the electrode reaction kinetics but also facilitates the charge separation and ionic conduction in SLFCs, consequently enhancing the fuel cell performance and electrical efficiency. The results confirmed the potential of stable operation for future practical deployment of SLFCs via appropriate selection of material and cell structure design. It is greatly believed that the physical junction plays a crucial role in overcoming the internal short-circuit issue of SLFCs.