Heterojunction Arrays Research Articles

A novel CaIn2S4/TiO2 NTAs heterojunction photoanode for highly efficient photocathodic protection performance of 316 SS under visible light

Designing heterojunction photocatalysts with matched band structure and good interface contact is an effective method to improve the photoelectrochemical activity. Herein, novel CaIn2S4/TiO2 nanotube arrays (NTAs) heterojunction photoanodes were successfully prepared by electrochemical anodization and hydrothermal method. The microstructures, compositions, crystal structures, chemical valence states and light absorption performances of the composites were evaluated by field emission scanning electron microscopy, energy dispersive x-ray spectroscopy transmission electron microscope, high-resolution transmission electron microscope, x-ray diffractometer, x-ray photoelectron spectroscopy and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), respectively. The photocathodic protection performances of CaIn2S4/TiO2 composites for 316 stainless steel (SS) and the influences of the CaIn2S4 content on the performances were studied. The microstructural examination revealed the uniform doping of CaIn2S4 nanofragments on the TiO2 NTAs, and the composite was made up cubic CaIn2S4 and anatase TiO2. The photogenerated electrons were transferred from the TiO2 to CaIn2S4 at the interface of the composite. Compared with pure TiO2 NTAs, CaIn2S4/TiO2 NTAs exhibited better photocathodic protection performance for 316 SS under visible light. Potential drop reached 0.78 V versus saturated calomel electrode for the 316 SS coupled with CaIn2S4/TiO2 NTAs. The photocurrent density of the 316 SS coupled with the composite photoanode (235.4 μA cm–2) was 17.4 times that of TiO2. The improved photocathodic protection property of CaIn2S4/TiO2 NTAs was ascribed to the enhanced separation efficiency of the photogenerated carriers and the strong visible light absorption of the material. The CaIn2S4/TiO2 NTAs exhibited continuous protection of the 316 SS for more than 12 h even in the dark. Therefore, the CaIn2S4/TiO2 NTAs heterojunction composite is an outstanding and efficient photoanode for the photocathodic protection of metals.

Improving the photoelectrochemical performance of spin-coated WO3/BiVO4/ZnO photoanodes by maximizing charge transfer using an optimized ZnO decoration layer

The photoelectrochemical (PEC) method has potential for harvesting solar energy to eventually resolve the fossil fuel crisis owing to its green and renewable characteristics and inherently low conversion efficiency. Herein, we introduce a controlled ZnO decoration layer on a WO3/BiVO4 type II heterojunction array using a facile spin-coating method to enhance the PEC performance of photoelectrodes. The ZnO decoration layer plays a crucial role in attaining superior charge transfer, reduced charge recombination, and stable photoactivity in the composite WO3/BiVO4/ZnO systems. An optimally decorated ZnO layer with oxygen vacancies in the WO3/BiVO4/ZnO photoanode allows extended light absorbance in the UV and visible wavelength regions with a narrow band gap and passivates the underlying WO3/BiVO4 type II heterojunction surfaces by covering the defect sites. Thus, the optimized WO3/BiVO4/ZnO-3 photoanode exhibits the highest photocurrent density (190 μA cm−2 at 1.23 VRHE) with the lowest onset potential (0.41 VRHE), reproducible photo-reaction under chopped light, the smallest charge transfer resistance in the Nyquist plot (1755 Ω), the highest quantum efficiencies for ABPE, IPCE, and APCE (0.036% at 0.92 VRHE, 6% at 380 nm at 1.23 VRHE and 11% at 380 nm, respectively), the highest reliability (30% decay after 1500 s), and high charge injection (63%) and charge separation (7.3%) efficiencies. These findings demonstrate that the component optimization in WO3/BiVO4/ZnO-x composite photoelectrodes is crucial in achieving high PEC performance by improving charge separation and reducing charge recombination.

Single-layer graphene-TiO2 nanotubes array heterojunction as photoanode to enhance the photoelectric of DSSCs

Photoanode optimization of the dye-sensitized solar cell (DSSC) is a crucial way to improve efficiency. In this investigation, a kind of heterojunction fabricated based on TiO2 nanotubes and graphene by wet transfer method, furthermore, the heterojunction was fabricated as photoanode of DSSC. This method has the advantages of simple operation and time-saving, and micromorphological characterization revealed that graphene and TiO2 combined well. UV–Visible diffuse-reflectance spectrum and photon-to-current conversion efficiency (IPCE) data demonstrated that the graphene transfer enhanced the cell's absorbance in the visible range and reduced the bandgap. The J-V curve was obtained under solar simulation, and the conversion efficiency of 4.18% was reached, which is 83% higher than that of graphene free cell. Therefore, the heterojunction of graphene/TiO2 nanotubes makes a promising prospect for further applications in DSSCs.

Geometric optimization and performance enhancement of PEDOT: PSS/GaAs NP array based heterojunction solar cells

Polymer/semiconductor nanostructure array based solar cells (SCs) exhibit extremely low optical losses, excellent light-harvesting, improved carrier lifetime, increased defect tolerance etc. and can be a new pathway for low-cost high efficiency SCs. In order to fabricate efficient heterojunction SCs, it is extremely necessary to evaluate their optimal geometric configuration theoretically. In this article, using 3D-finite difference time domain (FDTD) method, we have optimized the geometric configuration of poly (3, 4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) coated vertically aligned GaAs Nano pyramid (NP) array heterojunction SCs to obtain high average optical absorption and J sc of 92.2% and 41.1 mA/cm 2 , respectively. The optimized structure simulated in Lumerical Charge Solver DEVICE module, exhibit power conversion efficiency (PCE) of 15.9% despite low carrier mobility and lifetime of 1000 cm 2 v −1 s −1 and 2ns respectively. • Role of GaAs nanopyramids (NPs) in efficient light harvesting is studied. • Optimization of geometrical dimensions of the NPs is performed in terms of optical J sc . • Conformal coating of PEDOT:PSS results in absorption enhancement. • GaAs NPs/PEDOT PSS based solar cells exhibits PCE of ~13%.

Enhanced Light Trapping in Conformal CuO/Si Microholes Array Heterojunction for Self-Powered Broadband Photodetection

In this letter, we demonstrate the fabrication of a conformal CuO/Si microholes array heterojunction through the DC reactive magnetron sputtering from a high-purity Cu target. By using the monolayer graphene as the top electrode, the device served well as a self-powered vis-NIR photodetector, showing a high responsivity of 301.5 mA W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , specific detectivity of 7.96×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> Jones and a fast response speed (rise time 9.9 μ s and fall time 10 μs) upon 530 nm illumination. Compared to its planar counterpart, the responsivity was remarkably enhanced over the broadband region. The underlying reason should be ascribed to the improved light trapping in the microholes via the longitudinal Fabry-Perot (F-P) cavity resonance, according to theoretical simulation by finite-difference time-domain (FDTD) solution. Such an effect gave rise to an enhanced light-matter interaction, leading to the improved photoresponse. This work also opens up an effective way for the on-chip high performance photodetection due to the well compatibility with the current complementary metal-oxide-semiconductor (CMOS) technology.

A Multiplexed Self-Powered Dual-Photoelectrode Biosensor for Detecting Dual Analytes Based on an Electron-Transfer-Regulated Conversion Strategy.

Due to the inherent mechanism limitation of photocatalytic fuel cell based self-powered biosensors (PFC-SPBs), it was difficult to distinguish the power density of various photoactive materials or recognition events in one detection process, which made it lack multitarget quantitative capacity. In order to solve this problem, we proposed an electron-transfer-regulated conversion strategy for the construction of multiplexed PFC-SPBs. Herein, the n-type CdS/Fe2O3 nanorod array (NR) heterojunction and p-type CuBr semiconductor were used as photoactive materials to prepare the photoanode and photocathode. Based on the appropriate Fermi level differentiation between these two photoelectrodes, a self-powered sensing platform driven by visible light without external energy supply was achieved. In this design, two kinds of common and easily coexisting mycotoxins OTA and AFB1 acted as model analytes. The coupling of "signal off" and "signal on" was realized by controlling the electronic transmission on the interface between the photoanode and photocathode, so as to achieve the simultaneous detection of two mycotoxins. This work established a proof-of-concept for the integration of a dual-photoelectrode with dual-assay that could provide the innovative inspiration for the formation of a general multiplexed self-powered sensing platform.

A signal-on photoelectrochemical aptasensor for chloramphenicol assay based on 3D self-supporting AgI/Ag/BiOI Z-scheme heterojunction arrays

Severe challenges are still remained for development of highly sensitive, selective and stable photoelectrochemical (PEC) sensing technology, albeit with its broad application for chloramphenicol (CAP) detection. Herein, a novel “signal-on” PEC aptasensor was fabricated based on a 3D self-supporting Z-scheme AgI/Ag/BiOI heterojunction arrays subtly integrated with in-situ formed biocatalytic precipitation (BCP) for highly sensitive and selective determination of CAP. Impressively, the HRP modified CAP aptamer (HRP-CAP aptamer) was released from the electrode by its strong affinity to the introduced CAP, and gradually terminated the BCP reaction, in turn recovering the photocurrent. By virtues of the 3D self-supporting AgI/Ag/BiOI Z-scheme heterojunction arrays and BCP signal amplification strategy, the resultant PEC sensor exhibited a wide linear range of 2–250 nM with a limit of detection (LOD) as low as 0.226 nM (S/N = 3). This work opens a new avenue for design of PEC aptasensing strategy and exhibits the marvelous potential in bioanalysis of environmental samples.

Construction of BiVO4 nanosheets@WO3 arrays heterojunction photoanodes by versatile phase transformation strategy

A versatile phase transformation strategy was proposed to synthesize novel BiVO4 nanosheets (NSs)@WO3 nanorod (NR) and nanoplate (NP) arrays films. The strategy was carried out by following a three-step hydrothermal process (WO3→WO3/Bi2WO6→WO3/BiVO4). According to the characterization results, plenty of BiVO4 NSs grew well on the surface of WO3 NR and NP arrays films, thus forming the WO3/BiVO4 heterojunction structure. The prepared WO3/BiVO4 heterojunction films were used as the photoanodes for the photoelectrochemical (PEC) water splitting. As indicated by the results, the photoanodes exhibited an excellent PEC activity. The photocurrent densities of the WO3/BiVO4 NR and NP photoanodes at 1.23 V (vs RHE) without cocatalyst under visible light illumination reached up to about 1.56 and 1.20 mA/cmbrespectively.

Hierarchical sheet-on-sheet heterojunction array of a β-Ni(OH)2/Fe(OH)3 self-supporting anode for effective overall alkaline water splitting.

Rationally designing high-performance non-noble metal electrocatalysts is of essence to improve energy conversion efficiency in water splitting. Herein, a unique 3D hierarchical sheet-on-sheet heterojunction between Fe(OH)3 and β-Ni(OH)2 on pretreated Ni foam (NiFe-HD/pre-NF) was fabricated by a two-step strategy involving the interfacial hydrolysis-deposition of Fe2+ and electrodeposition of Ni2+. The presence of the Ni-O-Fe bridge at the Fe(OH)3/β-Ni(OH)2 heterointerface can induce interfacial electronic redistribution to form Ni3+ in NiFe-HD/pre-NF, and further strengthen the adsorption of OH- and weaken the O-H bond to change the rate-determining step (RDS) for accelerating OER kinetics. Benefiting from the sheet-on-sheet architecture and dual-phase synergism on NiFe-HD/pre-NF, the optimal NiFe-HD/pre-NF exhibits excellent OER performance with a lower overpotential of 256 mV at 100 mA cm-2, a small Tafel slope of 81 mV dec-1, high intrinsic activity and robust stability. Alkaline water-splitting using NiFe-HD/pre-NF as the anode requires ultralow cell voltages of 1.62 V and 1.83 V at current densities of 100 mA cm-2 and 400 mA cm-2, respectively, which are comparable with commercial alkaline water electrolysis, and operates steadily at a current density of 100 mA cm-2 for 85 h without decay. This work proposes a facile strategy for constructing heterojunctions and modulating electronic interaction to develop electrocatalysts with new architectures.

Direct Z-scheme WO3- nanowire-bridged TiO2 nanorod arrays for highly efficient photoelectrochemical overall water splitting

All-solid-state Z-scheme photocatalysts for overall water splitting to evolve H2 is a promising strategy for efficient conversion of solar energy. However, most of these strategies require redox mediators. Herein, a direct Z-scheme photoelectrocatalytic electrode based on a WO3-x nanowire-bridged TiO2 nanorod array heterojunction is constructed for overall water splitting, producing H2. The as-prepared WO3-x/TiO2 nanorod array heterojunction shows photoelectrochemical (PEC) overall water splitting activity evolving both H2 and O2 under UV–vis light irradiation. An optimum PEC activity was achieved over a 1.67-WO3-x/TiO2 photoelectrode yielding maximum H2 and O2 evolution rates roughly 11 times higher than that of pure TiO2 nanorods without any sacrificial agent or redox mediator. The role of oxygen vacancy in WO3-x in affecting the H2 production rate was also comprehensively studied. The superior PEC activity of the WO3-x/TiO2 electrode for overall water splitting can be ascribed to an efficient Z-scheme charge transfer pathway between the WO3-x nanowires and TiO2 nanorods, the presence of oxygen vacancies in WO3-x, and a bias potential applied on the photoelectrode, resulting in effective spatial charge separation. This study provides a novel strategy for developing highly efficient PECs for overall water splitting.

Scalable Integration of Coplanar Heterojunction Monolithic Devices on Two-Dimensional In2Se3.

The formation of lateral heterojunction arrays within two-dimensional (2D) crystals is an essential step to realize high-density, ultrathin electro-optical integrated circuits, although the assembling of such structures remains elusive. Here we demonstrated a rapid, scalable, and site-specific integration of lateral 2D heterojunction arrays using few-layer indium selenide (In2Se3). We use a scanning laser probe to locally convert In2Se3 into In2O3, which shows a significant increase in carrier mobility and transforms the metal-semiconductor junctions from Schottky to ohmic type. In addition, a lateral p-n heterojunction diode within a single nanosheet is demonstrated and utilized for photosensing applications. The presented method enables high-yield, site-specific formation of lateral 2D In2Se3-In2O3-based hybrid heterojunctions for realizing nanoscale devices with multiple advanced functionalities.

Programmable Single‐Crystalline PbI2 Microplate Arrays and Their Organic/Inorganic Heterojunctions

AbstractDeterministic patterning of inorganic semiconducting micro‐/nanostructures has laid the foundation for the on‐chip integration of optoelectronic devices. However, it requires complicated equipment for thin‐film deposition, lithography, and etching. Solution‐processing bottom‐up integration of micro‐/nanostructures has been extensively studied in organic semiconductors and nanoparticles, but solution‐patternable inorganic single‐crystalline micro‐/nanostructures are still elusive. It is still challenging to control the crystallization of inorganic semiconductors in solution processes. Herein, an efficient strategy is developed to steer the crystallization of PbI2 hexagonal microplates in capillary bridges. Evenly distributed mass and ordered microfluid in each capillary bridge are able to attain simultaneous manipulation of position, size, and crystallographic orientation. Complex patterns, including Latin characters, Arabic numeral characters, and mathematical symbols, are realized by positioning capillary bridges. Based on these high‐quality PbI2 microcrystals, high‐performance photodetectors are demonstrated with a responsivity of 625 mA W−1, an on–off ratio of 105 and response speeds of τrise = 0.31 ms and τdecay = 0.17 ms. This technique also allows for the integration of PbI2 microstructures with organic semiconductors to manufacture heterojunction arrays with efficient charge transfer. The strategy provides a perception to fabricate inorganic single‐crystalline microarrays and heterostructures for integrated optoelectronics.

Co-axial silicon/perovskite heterojunction arrays for high-performance direct-conversion pixelated X-ray detectors

Creating monolithic silicon/perovskite structures is a promising approach to engage emerging perovskite materials with silicon circuitry, which is essential to achieve industry-scale applications such as high performance X-ray detection. In particular, to achieve pixelated perovskite is a key step to address the issue of electrical crosstalk and low spatial resolution in imaging caused by inefficient migration and collection of carriers in the direction of signal collection. However, with the existing top-down methods, the thickness of patterned perovskite is limited to be in submicron level, which is far from highly efficient absorption of X-ray energy, further compromising the detection sensitivity. Here, we successfully demonstrate 3D hybrid perovskite crystal arrays with the thickness of ~300 μm on pixelated silicon substrate (forming co-axial silicon/perovskite heterojunction arrays) by melting PbBr2 and in situ chemical vapor conversion. Both morphological and optical properties of the resulting heterojunction arrays are systematically investigated. Furthermore, we demonstrate a high performance direct-conversion flat panel X-ray detector which exhibits high sensitivity of 242 μC Gyair−1 cm−2 that is much higher than the commercially available α-Se, and fast response speed (rising and falling time are 0.5 ms and 1.3 ms, respectively). The proposed strategy addresses the trade-off problem between the high sensitivity (requiring ~ mm-thickness perovskite crystal) and high spatial resolution (patterning of perovskite crystal) to achieve high-performance X-ray detection. This work not only offers a new pathway to fabricate pixelated μm-thick perovskite-based X-ray detectors, but also impacts on the application and functionalization of perovskite materials in silicon circuitry.

Enhanced Photovoltaic Performances of La-Doped Bismuth Ferrite/Zinc Oxide Heterojunction by Coupling Piezo-Phototronic Effect and Ferroelectricity.

Ferroelectric materials have drawn widespread attention due to their switchable spontaneous polarization and anomalous photovoltaic effect. The coupling between ferroelectricity and the piezo-phototronic effect may lead to the design of distinctive photoelectric devices with multifunctional features. Here, we report an enhancement of the photovoltaic performances in the ferroelectric p-type La-doped bismuth ferrite film (BLFO)/n-type zinc oxide (ZnO) nanowire array heterojunction by rationally coupling the strain-induced piezoelectricity in ZnO nanowires and the ferroelectricity in BLFO. Under a compressive strain of -2.3% and a 10 V upward poling of the BLFO, the open-circuit voltage (VOC) and short-circuit current density (JSC) of the device increase by 8.4% and 54.7%, respectively. Meanwhile, the rise (/decay) time is modulated from 153.7 (/108.8) to 61.28 (/74.86) ms. Systematical band diagram analysis reveals that the promotion of photogenerated carriers and boost of the photovoltaic performances of the device can be attributed to the modulated carrier transport behaviors at the BLFO/ZnO interface and the superposed driving forces arising from the adding up of the piezoelectric potential and ferroelectric polarization. In addition, COMSOL simulation results of piezopotential distribution in ZnO nanowire arrays and the energy band structure change of the heterojunction further confirm the mechanisms. This work not only presents an approach to design high-performance ferroelectric photovoltaic devices but also further broadens the research scope of piezo-phototronics.

In situ growth of Fe2WO6 on WO3 nanosheets to fabricate heterojunction arrays for boosting solar water splitting.

We demonstrate the construction of heterojunction arrays for boosting solar water splitting by combining in situ guided growth of heterointerfaces and energy band tuning. By directly growing an ultrathin Fe2WO6 layer on a preformed WO3 nanosheet array in full coverage, a uniform and dense array of intimately contacted WO3/Fe2WO6 heterojunction was created. The heterojunction array shows not only a largely broadened visible light absorption range but also a built-in interface polarization to accelerate hole transfer from WO3 to Fe2WO6. Meanwhile, fine-tuning to match energy levels at the heterojunction was achieved by doping WO3 with Fe (Fe-WO3), leading to improved electrical conductivity and reduced charge recombination. Photoanodes based on such heterojunction arrays have shown significantly enhanced photoelectrochemical (PEC) water splitting performance, clearly arising from the above-mentioned efforts. Furthermore, by decorating FeOOH/NiOOH cocatalysts on the heterojunction arrays in tandem, the surface water oxidation kinetics was considerably accelerated, and the resulting Fe-WO3/Fe2WO6/FeOOH/NiOOH photoanode achieved a photocurrent density of 2.78 mA/cm2 at 1.23 V vs reversible hydrogen electrode. This work highlights the benefits of in situ construction of heterojunction arrays for enhancing the PEC performance.

UV Photodetector Based on Vertical (Al, Ga)N Nanowires with Graphene Electrode and Si Substrate

As the key device in a UV warning system, a solid‐state UV photodetector has attracted great attention. Herein, a new UV photodetector structure based on vertical (Al, Ga)N nanowires with graphene electrode and Si substrate is designed and demonstrated. By graphene/vertical (Al, Ga)N nanowire array heterojunction, the rectifying characteristics of I–V curve are formed, and the dark current is 54 nA at −2 V bias. The fabricated device exhibits a responsivity of 0.176 mA W−1 at the bias of −2 V, as well as a stable switching characteristic. It is proposed that the photogenerated electrons and holes can reach positive and negative electrodes by diffusion or tunneling effect, even with thick AlN sections. This method can promote the implementation of low cost for UV photodetector with adjustable detection range nowadays.

The improved photoresponse properties of self-powered NiO/ZnO heterojunction arrays UV photodetectors with designed tunable Fermi level of ZnO

Self-powered ultraviolet (UV) photodetectors (PDs) based on ZnO heterojunctions have attracted more attention due to the simple preparation and excellent photoresponse performance without any power supply. The self-powered UV PDs based on NiO nanoflakes/ZnO nanorod arrays (NRs) heterojunctions were fabricated by a low-cost, simple chemical bath deposition (CBD) method. The crystal quality, optical and electronic properties of ZnO NRs is modified by Al3+ ions additions in the precursor solution. The heterojunction devices with ZnO NRs grown in 0.5% Al3+ ions additions precursor solution exhibit a narrow UV spectral selectivity, high photoresponsivity R (85.12 mA/W) and detectivity D* (1.74 × 1012 cm·Hz1/2/W) and a fast response speed (~2 ms) under 378 nm UV light for low intensity irradiance (0.2 mW/cm2) at zero bias. The large built-in electric field of the NiO/ZnO heterojunction with the increased Fermi level of ZnO NRs provide a strong driving force to separate and transfer the photo-generated carriers, decrease the recombination of the carriers and then improve the photoresponse performance of heterojunction devices without external bias.

Highly efficient photoelectrochemical water splitting from P-doped α-Fe2O3 nanorod/BiVO4 heterojunction array

We report the fabrication of P-doped α-Fe2O3 nanorod/BiVO4 heterojunction photoelectrode for photoelectrochemical (PEC) water splitting. The heterojunction photoelectrode is fabricated by combining methods of hydrothermal deposition, wet impregnation and metal organic decomposition. The structure and PEC activity of the photoelectrode are systemically studied. This heterojunction photoelectrode exhibits a surprising photocurrent density of 1.17 mA/cm2 at 0.8 V vs. Ag/AgCl, which is approximately 3.55 times higher than that of the pristine α-Fe2O3. The photoconversion efficiency is 9.58 times higher than α-Fe2O3 and the onset potential has an obvious negative shift of 450 mV compared to the α-Fe2O3 for the heterojunction photoelectrode. The significant enhancement of PEC water splitting performance is attributed to the heterojunction structure and the synergistic effects of P-doping, which contributes to expediting electron and hole transfer and reducing carriers recombination. This novel design may provide an efficient way to developing efficient heterojunction photoelectrodes for practical PEC application.

A Self‐Powered High‐Performance UV Photodetector Based on Core–Shell GaN/MoO3–x Nanorod Array Heterojunction

AbstractSelf‐powered UV photodetectors are highly desirable for applications in space communications and environmental monitoring. However, most self‐powered UV photodetectors exhibit unimpressive performance in weak signal detection. Herein, a self‐powered UV photodetector based on the core–shell GaN/MoO3–x nanorod array (NRA) heterojunction system is demonstrated. Homogeneous MoO3–x layers are deposited on GaN NRAs by a simple one‐step physical vapor deposition method. The photodetector device shows an ultrahigh specific detectivity of 2.7 × 1015 Jones at 355 nm without any power supply. Further analyses reveal a responsivity of 160 A W−1 and a high UV–vis rejection ratio (R355 nm/R400 nm) of 2.0 × 104 under zero bias. The self‐powered device also has a fast response speed with a rise/fall time of 73/90 µs. As a result, the self‐powered photodetector, featuring ultrahigh detectivity and responsivity along with fast response, exhibits great potential for applications in next‐generation UV detection. The core–shell NRA structure heterojunction design provides a valuable direction for realizing nanoscale self‐powered UV photodetectors.

Low-temperature growth of Three dimensional ReS2/ReO2 metal-semiconductor heterojunctions on Graphene/polyimide film for enhanced hydrogen evolution reaction

Flexible inorganic electronics (FIE) have shown unique advantages in energy conversion, aerospace and wearable devices due to excellent electronic properties and thermostability of inorganic materials. The industrialization of high-performance flexible inorganic electronics (FIE) devices requires universal approaches to fabricate inorganic crystal on polymer substrates at acceptable temperature. Herein, we firstly developed the vortex flow chemical vapor deposition (VFCVD) for low temperature synthesis of high-quality vertical ReO2 arrays at 450 °C on flexible graphene-polyimide (G-PI) conductive film. The Euler equations suggest that the vapor pressure of ReO2 is almost 100-times higher than that of free space with VFCVD at identical conditions. The derived ReS2/ReO2 metal-semiconductor heterojunction arrays are performed outstanding hydrogen evolution reaction (HER) activity with high long-term stability as an energy conversion device. This work opens up an opportunity for low temperature growth of inorganic nanomaterials on polymer substrates by VFCVD for the industrialization of high-performance flexible energy devices.