Heterostructure Electrode Research Articles

Heterostructure of nickel cobalt metaphosphate nanoneedles decorated with NiMn layered double hydroxide nanosheets for supercapacitors

Constructing heterostructured electrode materials with well-designed components and nanostructures is a promising strategy to enhance the electrochemical performance of supercapacitors. In this study, a rational heterostructured composite of nickel cobalt metaphosphate (Ni0.4Co0.6(PO3)2) nanoneedles decorated with NiMn layered double hydroxide (NiMn-LDH) nanosheets has been fabricated on carbon paper (CP) substrate by sequential hydrothermal method, phosphorization, and hydrothermal treatment. This well-aligned Ni0.4Co0.6(PO3)2@NiMn-LDH core–shell heterostructure not only exposes abundant electroactive sites to participate in reversible electrochemical reactions, but also offers short pathways for rapid electron/ion transport and buffers volume changes during charging/discharging processes. Benefiting from these structural merits and component synergistic effect, the self-supporting Ni0.4Co0.6(PO3)2@NiMn-LDH electrode displays a high capacity of 1147.9C/g (1913 mC cm−2) at 1 A/g and a capacity retention of 95.2 % after 5000 cycles in a tri-electrode cell. Besides, the assembled aqueous Ni0.4Co0.6(PO3)2@NiMn-LDH-based hybrid supercapacitor presents an energy density of 71.5 Wh kg−1 (0.24 mWh cm−2) at a power density of 732.9 W kg−1 (2.5 mW cm−2) and retains 94.4 % of the initial capacity over 10,000 cycles. This work provides an efficient hybridization approach to design high-performance electrode materials for advanced energy storage devices.

One-step construction of Ti3C2Tx/MoS2 hierarchical 3D porous heterostructure for ultrahigh-rate supercapacitor

Heterostructures based on different materials can not only take full advantage of each material and overcome their limitations but also produce special effects for different applications. Here, a facile co-thermal decomposition strategy to engineer hierarchical 3D porous Ti3C2Tx/MoS2 heterostructure is presented for improved energy storage performance. The specific Ti3C2Tx/MoS2 heterostructure promotes the fast transportation of electrons and ions and fast redox reaction kinetics due to the 3D interconnected porous channels and thin exposed electroactive S-Mo-S edges. As a result, the 3D porous Ti3C2Tx/MoS2 heterostructure exhibits a specific capacitance of 439 F g-1 at a scan rate of 5 mV s−1, a satisfactory capacitance of 169 F g-1 (about 30 % of initial capacitance) under an ultra-high scan rate of 10,000 mV s−1 and long cycle stability. Moreover, ultrahigh power energy of 30,000 W kg−1 with a high energy density of 6.3 Wh kg−1 with superior cyclic stability (91 % of initial capacitance after 10,000 cycles) has been achieved from the Ti3C2Tx/MoS2-based symmetric supercapacitor. This work provides an archetype for designing and preparing hierarchical 3D porous heterostructure electrodes for the next-generation supercapacitor with the high power density and rate performances.

Efficient and stable heterostructured air electrode for solid oxide steam electrolysis

High performance and excellent durability are essential for the practical application of solid oxide electrolysis cell (SOEC). Here we have demonstrated efficient and durable solid oxide steam electrolysis by constructing active La0.8Sr0.2CoO3-δ/Gd0.2Ce0.8O2-δ (LSC/GDC) heterointerface in air electrode using a simple co-impregnation method. The heterostructured air electrode exhibits the outstanding activity for oxygen evolution reaction, and its exchange current density (557 mA cm−2) is 69 times higher than that of the traditional LSM-YSZ. The resulting cell reaches −1.86 A cm−2 @1.3 V and −2.30 A cm−2 @1.5 V at 800 °C and 50% absolute humidity (A.H), and the polarization resistance from the oxygen electrode only is 0.02 Ω cm2. Most importantly, the heterostructured cell presents excellent long-term stability for the 1035 h steam electrolysis operation and excellent durability for 100 times charge-discharge cycles. In the heterostructured air electrode, the problem of electrode delamination is avoided due to the reduced oxygen partial pressure at anode/electrolyte resulting from easy diffusion of O2− at the interphase, and the coarsening of LSC and GDC nanoparticles is limited because of the LSC/GDC percolative interfaces from phase segregation process. This work proposes a simple and effective strategy to design heterointerface for efficient and durable solid oxide steam electrolysis.

High capacity and stability induced by sandwich-like structure and metal–O configuration for CoNi2S4/Ti3C2Tx heterostructure electrode

A two-dimensional heterostructure, combined with the collective advantages of single building blocks, has attracted considerable interest as a new paradigm in the materials design of electrochemical energy storage. In the present study, a sandwich-like CoNi2S4/Ti3C2Tx heterostructure electrode was successfully acquired using a simple one-step hydrothermal procedure, where CoNi2S4 nanosheets are distributed uniformly within the MXene interlayers and on surfaces. The layered structure of MXene restricts the overgrowth of CoNi2S4. The tiny size shortens the charge transfer and ion diffusion pathway and minimises the volume change in CoNi2S4. The introduction of CoNi2S4 expands the interlayer distance of the host MXene, enabling fast ion movement and efficiently accommodating the volume expansion of CoNi2S4. The electronic coupling of the metal in CoNi2S4 and O in Ti3C2Tx improves the electrical conductivity and optimises the absorbability and stability of OH– on the heterostructure. The CoNi2S4/Ti3C2Tx heterostructure delivered a capacity of 320 mAh g–1 (2398 F g–1) at 1 A g–1 and a capacity retention of 80% at 25 A g–1 after 40, 000 cycles, outperforming most supercapacitor electrode materials reported to date owing to the synergy between the structural configuration and electronic interactions. This work provides valuable insights for designing high-performance electrode materials by manipulating the structural configuration and interface electronic interaction.

MoS2/carbon heterostructured catalysts for the hydrogen evolution reaction: N-doping modulation of substrate effects in acid and alkaline electrolytes

Carbon-supported MoS2 is a promising electrocatalyst for hydrogen evolution reaction (HER), however, it is not well understood how carbon substrate effects might modulate MoS2 activity. Herein, we report on development and characterization of heterostructured thin-film electrodes consisting of MoS2 supported on nitrogenated graphitic carbons, that display well defined geometry, morphology and concentration of N-functionalities. Carbon supports were synthesized via magnetron sputtering and thermal modifications, yielding graphitized smooth thin-films rich in either pyridinic-N or graphitic-N functionalities. CVD deposition of MoS2 using close proximity precursor methods yielded MoS2/carbon electrodes with high contact area between the two phases, thus enabling investigation of substrate effects on MoS2 activity. Voltammetry in acid and alkaline electrolytes indicates that N-functionalities affect HER performance with effects being pH-dependent. At low pH, similar overpotentials and Tafel slopes are observed independently of whether graphitic-N or pyridinic-N groups are present at the carbon support. However, at high pH, pyridinic-N groups lead to suppression of HER activity. We propose that deprotonation and lone-pair availability at pyridinic-N modulate activity with electrostatic interactions leading to weaker MoS2-carbon coupling for the deprotonated form. This has important implications for smart design of heterostructured electrocatalysts where synergistic/inhibitory behaviors might be exploited/avoided to control performance in HER electrocatalysis.

Porous-tube arrays with electron-correlated strong synergy of sulfide/ phosphide heterostructures for ultrahigh-capacity and stable battery

This study reports a significant advance toward the multicomponent design and fabrication of novel hierarchical porous-tube array electrodes by engineering surfaces and interfaces of different active materials. The hierarchical electrodes with an electron-correlated strong synergy of traditional bimetallic sulfide/phosphide heterostructures were achieved by controlled ion-exchange processes. Each submicron-sized tube has a porous shell consisting of Fe7(PO4)6 inner layer with metalloid-like electrical conductivity wrapped by interlaced ultrathin CoS nanoflakes, which provides both a stable nano-micron architecture and highly active heterostructure interfaces. The CoS/Fe7(PO4)6 heterostructure electrode showed an ultrahigh specific capacity reaching up to 461.5mAh·g−1 at 5 mA·cm−2, much higher than that of a single component and previously reported multicomponent ones. Particularly, the electrode also showed remarkable stability with capacity retention of 92.0% after 10,000 charge-discharge cycles at a high current density of 30 mA·cm−2. The practical application demonstrated that two connected devices in a series can power 16 LEDs. This work provides an effective pathway to hierarchical heterostructure arrays for energy storage devices with high energy density, fast recharging ability, and long cycle life.

ALD-fabricated two-dimensional SnO2-In2O3n-n nanohybrid electrode for electrochemical supercapacitors

Fabrication of thin-film heterostructured electrodes with thickness below 10.0 nm is of great importance for the development of high-performance electrochemical supercapacitors (ESCs) with great capabilities. This is because such electrodes with uniform thicknesses enable fast electrochemical responses during charging/discharging ascribed to their short charge and ion diffusion lengths. In this study, two-dimensional (2D) SnO2-In2O3 heterostructures with a thickness of ∼7.84 nm was fabricated on Au/SiO2/Si wafers by the atomic layer deposition (ALD) technique for ESCs application. Various spectroscopic and microscopic analyses demonstrated the formation of 2D SnO2-In2O3 heterojunction with high purity, crystallinity and homogeneous morphology. Cyclic voltammetry (CV) measurements revealed the pseudocapacitive Faradaic redox reactions with good reversibility for 2D SnO2-In2O3 heterostructure. The heterostructured electrodes demonstrated excellent super-capacitive performance with high specific capacitance (Cs) up to 1048.25 and 757 F g−1 at the scan rate and the current density of 10 mV s−1 and 12 A g−1, respectively. Accordingly, a high energy density of 51.55 Wh kg−1 is attained at 12 A g−1. The high super-capacitive performance of these heterostructures can be attributed to the improved redox activity and short ion diffusion length of the SnO2-In2O3 nanohybrid thin-film. The electrodes also demonstrated great electrochemical stability with the Cs retention of 96.15% even after 5000 charge/discharge cycles.

Mixed metal chalcogenide shell with carbon interlayer wrapped 3D NiCo 2 O 4 nanowire array: A hierarchical self‐supported electrode for high‐performance supercapacitors

The expansion of effective mass transportation and elevated electrochemical active sites are cogent strategies for designing hierarchical transition metal-based heterostructures electrodes in high-performance supercapacitors (SC). In this study, we fabricated a self-supported three-dimensional NiCoO@NC@NiCoMnSe core-shell nanowire array (NWA) on Ni foam via a two-step hydrothermal process followed by vapor phase selenification. Fabricated multivalent heterostructured core-shell NWA electrode exhibited a high areal capacity of 0.761 mA h cm−2 (2.73 C cm−2) at 2 mA cm−2 with cyclic stability of 83.1% after 5000 cycles at 30 mA cm−2. An assembled HSC device with NiCoO@NC@NiCoMnSe as a positive electrode and activated carbon (AC) as a negative electrode exhibited a high volumetric energy density of 3.87 mWh cm−3 at a volumetric power density of 20.17 mW cm−3 and further retained an energy density of 2.64 Wh cm−3 at a power density of 201.5 W cm−3. The HSC exhibited high-capacity retention of 98.2% after 10 000 cycles at 6 mA cm−2, evidence of the high durability of the rich redox-active heterostructured electrode. A thin carbon nanowall between the core and shell interface enriched the mass electron transfer, reduced the impedance, and promoted its structural durability, resulting in the heterostructure's superior electrochemical performance.

Red@Black phosphorus core–shell heterostructure with superior air stability for high-rate and durable sodium-ion battery

Heterostructured electrodes have gained increasing attentions owing to the synergistic effects from individual building components and the unique interfaces. However, rational design and controllable fabrication of high areal capacity and durable phosphorus-based heterostructure anode for industry remains a critical challenge. Herein, a new red@black phosphorus core–shell heterostructure anchored on three-dimensional N-doped graphene (RP@BP/3DNG) has been prepared via a facile one-step solvothermal strategy. As demonstrated by experimental data and theoretical calculations, RP@BP/3DNG shows a superior high electronic conductivity and an extremely low Na+ diffusion barrier due to the build-in filed at the RP@BP heterointerface, thus RP@BP/3DNG delivers an ultra-high areal capacity of 3.46 mAh cm−2 (1440.2 mAh/g at 0.05 A/g), impressive rate performance (521.3 mAh/g at 10.0 A/g) as well as unprecedented capacity retention rate of 89.3% after 1200 cycles at 10.0 A/g when evaluated as an anode for sodium ion batteries (SIBs). Furthermore, the internal electric field at the interfaces of RP@BP leads to the shift of electron cloud from BP to RP, which greatly suppresses the reaction activity of lone-pair electrons of BP atoms, and therefore RP@BP/3DNG shows much enhanced air stability. This work heralds a new insight for designing high-performance and stable P-based anodes for rechargeable batteries.

Covalent‐Induced Heterostructure of Covalent‐Organic Frameworks and MXene as Advanced Electrodes with Motivated Pseudocapacitance Performance

AbstractHeterostructures based on covalent organic frameworks (COFs) and conductive materials have attracted more attentions to effectively apply COF‐related materials for supercapacitor. Here, the as‐prepared amino‐modified Ti3C2 MXene nanosheets are adopted to support the in‐situ growth of anthraquinone‐based COFs (AQ‐COF) to fabricate the heterostructures of COFs uniformly dispersed on surface of MXene, based on the covalent interaction between terminal C=O groups of COFs and amino units of MXene. Besides, the morphology and porous structures of COF@MXene heterostructures are optimized by controlling the amounts of MXene nanosheets. Combining the superiority from the two‐dimensional structure with high conductivity of MXene and porous structure with abundant redox‐active groups inherited from AQ‐COF, the COF@MXene‐15 heterostructure electrode delivers large surface area with optimal porous structures, leading to the maximally‐activated C=O units for charge‐storage and capacitance‐controlled electrochemical kinetics. Improved specific capacitance (290 F g−1 at 0.5 A g−1) and rate capability can be achieved for the COF@MXene‐15 heterostructure as the electrode for supercapacitor in Na2SO4 electrolyte. It is the first time to report the heterostructure of COFs and MXene as the electrode for supercapacitor, and this work would promote further application of COFs and related materials for other energy‐storage systems.

Rational construction of 2D/2D Ti3C2Tx/NiCo MOF heterostructure for highly efficient Li+ storage

Metal-organic framework (MOFs) have been regarded as ideal lithium-ion battery (LIB) anodes with abundant active sites, porous structure, shortened ion diffusion pathways, and adjustable component, but the MOF anodes suffer from the low electronic conductivity. Herein, we rationally design a 2D/2D Ti3C2Tx/NiCo MOF heterostructure through in-situ growth of ultrathin NiCo MOF nanosheets on the few-layer Ti3C2Tx MXene sheets. The carboxylate groups of BDC2− can form stable bond with the termination groups (e.g., -OH) on the Ti3C2Tx surface and hydroxyl groups in the lignin molecules, resulting in stable Ti3C2Tx/NiCo MOF interface and good structure stability of the 2D/2D Ti3C2Tx/NiCo MOF heterostructure. The Ti3C2Tx/NiCo MOF heterostructure could combine the advantages of 2D MXene nanosheets and 2D bimetallic MOF structure. The 2D bimetallic NiCo MOF can offer plenty of exposed active sites for Li+ intercalation, while the 3D conductive network structure based on the Ti3C2Tx can not only enhance the electronic conductivity, but also facilitate the electrode/electrolyte interface contact and promote the charge diffusion. The obtained 2D/2D Ti3C2Tx/NiCo MOF heterostructure anode demonstrates a high capacity of 637 mAh g−1 at 0.2 A g−1 after 200 cycles. Furthermore, the Li+ intercalation/extraction mechanism of the Ti3C2Tx/NiCo MOF heterostructure electrode is explored in detail.

Heterostructured Functional Materials through Molten Salt Synthesis for Solid Oxide Fuel Cells and Electrolysis Cells

La0.6Sr0.4Co0.2Fe0.8O3 (LSCF)−La0.8Sr0.2MnO3 (LSM) heterostructure crystalline materials have been synthesized in a simple, one-step via reaction-deposition process using a molten salt. Two-phase perovskite composites can be synthesized in times as short as 10 minutes in a molten salt solvent. X-ray diffraction and S/TEM energy dispersive X-ray spectroscopy have been utilized to confirm the formation of an LSM shell on LSCF cores in all samples when adjusting dwell time, core size, weight ratio between core and shell precursors, and weight ratio of powder to salt. Specifically, decreasing the LSCF core size increases core−shell yield. Smaller cores result in a greater density of facets on the crystal surface and provide more favorable sites for LSM heterogeneous nucleation. By decreasing the weight ratio of shell precursor to core decreases shell thickness, and reduces the number of homogeneously nucleated LSM nanoparticles, and thereby increases core−shell yield. Increasing the amount of molten salt solvent relative to precursors decreases supersaturation in the melt and results in less uniform, and isolated shell deposition on the cores. The synthesized heterostructred nanoparticles have been functionalized into electrodes for solid oxide fuel cells and electrolysis cells. Symmetrical cells fabricated from baseline LSCF electrodes are compared with symmetrical cells fabricated from the molten salt-synthesized heterostructred electrodes. The heterostructured electrodes are shown to have significantly lower polarization resistance compared to baseline LSCF electrodes, showing the promise of the molten salt process to achieve heterostructured electrodes with substantially reduced polarization resistance.

Construction of MoS2 intercalated Siloxene heterostructure for all-solid-state symmetric supercapacitors

Two-dimensional (2D) heterostructure electrode materials have recently attracted great interest in supercapacitors because of their unique features. Herein, we report molybdenum disulfide (MoS2) intercalated Siloxene heterostructure based all-solid-state symmetric supercapacitor (SSC) for an energy harvester-storage system. The interlaying spacing of the Siloxene sheets in the heterostructure is expanded due to the MoS2 intercalation and the synergistic behaviour, which are fruitful for the higher charge storage performance of the fabricated SSC device. The density functional theory calculation results prove the enhanced conductivity of the Siloxene@MoS2 heterostructure. The fabricated Siloxene@MoS2 device exhibits a device capacitance of 133.5 F g–1 with an energy density of 31.3 Wh kg–1. Besides, the supercapacitor device has excellent cyclic stability of 89.3% after 15,000 cycles. The energy stored from an inertial energy harvester is successfully utilized for real-time application, confirming the practical usage of the constructed energy harvester-storage system. The outcome of the work demonstrated that the Siloxene@MoS2 heterostructure could be a promising candidate for high-performance supercapacitors and provides a novel strategy to design Siloxene material with other pseudocapacitive for future energy storage devices.

Developing Potential Energy Surfaces for Graphene-Based 2D–3D Interfaces From Modified High-Dimensional Neural Networks for Applications in Energy Storage

Abstract Designing a new heterostructure electrode has many challenges associated with interface engineering. Demanding simulation resources and lack of heterostructure databases continue to be a barrier to understanding the chemistry and mechanics of complex interfaces using simulations. Mixed-dimensional heterostructures composed of two-dimensional (2D) and three-dimensional (3D) materials are undisputed next-generation materials for engineered devices due to their changeable properties. The present work computationally investigates the interface between 2D graphene and 3D tin (Sn) systems with density functional theory (DFT) method. This computationally demanding simulation data is further used to develop machine learning (ML)-based potential energy surfaces (PES). The approach to developing PES for complex interface systems in the light of limited data and the transferability of such models has been discussed. To develop PES for graphene-tin interface systems, high-dimensional neural networks (HDNN) are used that rely on atom-centered symmetry function to represent structural information. HDNN are modified to train on the total energies of the interface system rather than atomic energies. The performance of modified HDNN trained on 5789 interface structures of graphene|Sn is tested on new interfaces of the same material pair with varying levels of structural deviations from the training dataset. Root-mean-squared error (RMSE) for test interfaces fall in the range of 0.01–0.45 eV/atom, depending on the structural deviations from the reference training dataset. By avoiding incorrect decomposition of total energy into atomic energies, modified HDNN model is shown to obtain higher accuracy and transferability despite a limited dataset. Improved accuracy in the ML-based modeling approach promises cost-effective means of designing interfaces in heterostructure energy storage systems with higher cycle life and stability.

TiVCTx MXene/Chalcogenide Heterostructure-Based High-Performance Magnesium-Ion Battery as Flexible Integrated Units.

Magnesium-ion batteries (MIB) have gradually attracted attention owing to their high theoretical capacity, high safety, and low cost. A bimetallic metal-organic framework self-sacrificing template and a co-assembly strategy are used to prepare a high-performance, stable cycling NiSe2 -CoSe2 @TiVCTx (NCSe@TiVC) heterostructure MIB cathode that can be used as a flexible integrated unit to power future self-powered systems. Benefiting from the synergistic effect of TiVCTx MXene and NCSe, the NCSe@TiVC heterostructure electrode has a discharge-specific capacity of 136mAhg-1 at 0.05Ag-1 and high cycling stability of over 500 cycles; the assembled pouch-cell device as flexible integrated unit exhibits good practicability. The magnesium ion storage mechanism is also validated using quantitative kinetic analysis, ex situ XRD, and XPS techniques. Density functional theory analysis indicates the most stable Mg-atom adsorption sites in the heterostructure. This study broadens the possibilities for applying the TiVCTx MXene heterostructure to energy storage materials and future self-powered flexible systems.

The coplanar graphene oxide/graphite heterostructure-based electrodes for electrochemical supercapacitors

Graphene-based foams were widely applied as electrode (or substrate) in energy storage devices. However, many efforts were spent on exfoliation, purification and fabrication process as the graphene-based materials were mostly fabricated by the assembly of GO nanosheets. In this work, a novel top-down strategy was presented to directly fabricate the GO/graphite foam from graphite paper. Under a controllable intercalation/expansion method, the graphite layers were partly expanded (and oxidized) and cross-linked by the coplanar GO/graphite heterostructure. The expanded GO parts endowed the electrode high surface area and pseudocapacitance, while the coplanar unexpanded graphite parts supported the electrode with hierarchical nanostructure and superior conductive network. The synergistic effect with GO and graphite greatly enhanced the electrochemical performance of the heterostructure electrodes. This method suggests an alternative to revisit the electrode production made from graphite and GO, which could greatly simplify the production flow of graphene-based electrodes.

Photo‐Responsive Molecular Junctions Activated by Perovskite/Graphene Heterostructure Electrode (Advanced Optical Materials 11/2022)

Photo‐Responsive Molecular Junctions Activated by Perovskite/Graphene Heterostructure Electrode (Advanced Optical Materials 11/2022)

Enhanced capacitive deionization by rGO@PEI/MoS2 nanocomposites with rich heterostructures

Heterostructure electrodes prepared from the nanocomposite rGO/MoS2 have become one of the hot spots for capacitive deionization (CDI) research due to their excellent electrochemical properties. However, during the preparation process, the electrostatic repulsion by the electronegativity of graphene oxide (GO) and MoS2 precursor (molybdate ion) led to the undesirable combination of rGO and MoS2. Only a small amount of MoS2 existed on the surface of rGO, which was not conducive to the formation of heterostructures between rGO and MoS2. In this work, GO was modified by the positively charged polyethyleneimine (PEI), forming the GO@PEI with positively charged surfaces. Due to the electrostaticinteraction with the precursors (Molybdate ions) of MoS2, the rGO@PEI/MoS2 composites with rich heterostructures were successfully prepared. As result, the rGO@PEI/MoS2 composites exhibited high specific capacitance, excellent cycle stability, and enhanced desalination performance. The rGO@PEI/MoS2 had a maximum specific capacitance of 212.53F/g, which was a 45% improvement over rGO/MoS2. The maximum electro-adsorption of the rGO@PEI/MoS2 electrode was about 24.13 mg/g with pole plate spacing of 1 mm at 1.0 V. The excellent electrochemical properties and desalination capability of the rGO@PEI/MoS2 composite were attributed to the synergistic effect generated by the rich heterostructure. The rich heterostructure formed between rGO and MoS2 through van der Waals forces and chemical bonding (Mo-N-C) perfectly combined their advantages and counteracted their disadvantages.

In-situ hydrothermal synthesis of Ni–MoO2 heterostructure on porous bulk NiMo alloy for efficient hydrogen evolution reaction

The Ni–MoO2 heterostructure was synthesized in suit on porous bulk NiMo alloy by a facile powder metallurgy and hydrothermal method. The results of field emission scanning electron microscopy (SEM), field emission transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) reveal that the as-prepared electrode possesses the heterostructure and a layer of Ni(OH)2 nanosheets is formed on the surface of Ni–MoO2 electrode simultaneously after hydrothermal treatment, which provides abundant interface and much active sites, as well as much active specific surface area. The results of hydrogen evolution reaction indicate that the Ni–MoO2 heterostructure electrode exhibits excellent catalytic performance, requiring only 41 mV overpotential to reach the current density of 10 mA/cm2. It also possesses a small Tafel slope of 52.7 mV/dec and long-term stability of electrolysis in alkaline medium.

Photo‐Responsive Molecular Junctions Activated by Perovskite/Graphene Heterostructure Electrode

AbstractPhotoresponsivity is a fundamental process that constitutes optoelectronic devices. In molecular junction devices, one of the most adopted strategies is to employ photoactive molecules that can undergo conformational change upon light illumination as the conduction channel. However, such devices suffer from their relatively low photoresponsivity, long switching time, and unidirectional switching. In this study, the authors employed organohalide perovskite (OHP)/graphene heterojunction as a photoactive electrode that acted a source of photo‐generated carriers collected as photocurrent in self‐assembled monolayer (SAM)‐based molecular junctions. This hybrid device architecture of perovskite/graphene/SAM allows the molecular junctions to attain a high photoresponsivity with molecules that have intrinsically little photoresponse. The authors elucidate the role of the molecular SAM in enhancing the photoresponsivity by systematically examining the transport and charge transfer processes at the graphene/SAM interface via molecules with different intrinsic dipole moments. This, corroborated with a theoretical analysis, reveals the origin of the observed photoresponsivity as light‐induced coupling between the SAM and the OHP/graphene electrode within the orbital‐mediated resonant tunnelling transport regime. These findings advance the understanding of photo‐induced charge transport in molecular junctions with heterointerfaces, providing a road‐map for designing high‐performance molecular optoelectronic devices based on hybrid device architecture.