Vapor Deposition Method Research Articles

Electrodeposition of Tribological Molybdenum Disulfide Coatings on Stainless Steel

MoS2 is an excellent solid-state lubricant for applications in space systems. Among various methods for MoS2 deposition, electrodeposition has the potential advantage over vapor deposition methods in achieving coatings on parts with complex geometries. This presentation will describe methods to electrodeposit smooth, crack-free, low-friction, and wear-resistant coatings of MoS2 on stainless steel at room temperature. The MoS2 films can be directly deposited on stainless steel without the need for anodic pretreatments or an adhesion layer, giving a low surface roughness comparable to that of the polished steel surface. The incorporation of stabilizing additives to the deposition bath not only enables the long-term stability of the solution under ambient environment, but also improves the uniformity of the coating over the substrate surface while maintaining a consistent S:Mo ratio of 2:1 across the thickness of the film. Additionally, coatings deposited from additive-free baths are amorphous, whereas those produced with additives are a composite of both amorphous and crystalline MoS2 regions. Coatings deposited with or without bath additives both display initially high friction and long run-in times but achieve low steady-state coefficients of friction and wear rates comparable to MoS2 coatings prepared by physical vapor deposition. Post-deposition mild annealing of the electrodeposited films under inert gas substantially reduces the initial friction and run-in times. Ongoing efforts to adopt the electrodeposition method for coating small parts with complex geometries such as pins and bearings will also be presented, as well as detailed information about the chemical composition and mechanistic roles of the additives in the improved deposition bath, methods to prevent film cracking during drying, and the role of mild thermal annealing.

Highly dispersed g-C3N4 on one-dimensional W18O49/carbon nanofibers for constructing well-connected S-scheme heterojunctions with synchronous H2 evolution and pollutant degradation performance

Synchronous dual-functional photocatalytic reaction can simultaneously consume photogenerated electrons and holes, leading to redox reaction, which is a promising photocatalytic reaction system model. However, the severe recombination of photogenerated charge carriers in photocatalysts limits their photocatalytic performance. In this work, W18O49/C@g-C3N4 S-scheme heterojunctions nanofibers with core-shell structure were prepared through electrospinning combined with the vapor deposition method, for high-performance synchronous photocatalytic H2 evolution and pollutant degradation. The X-ray photoelectron spectroscopy and Mott-Schottky results demonstrated that the S-scheme heterojunctions effectively separate charges while maintaining high redox capacity. The UV-vis-NIR absorption spectra results revealed the LSPR effect in W18O49, which can generate “hot electrons”. The scanning electron microscope images showed that the unique core-shell structure independently consumes electrons and holes, thereby enhancing charge separation and accelerating carrier kinetics. Specifically, the synchronous H2 evolution and RhB degradation efficiency of W18O49/C@g-C3N4 nanofibers were approximately 5.60 and 3.51 times higher than that of W18O49/C, and 2.45 and 22.55 times higher than that of C@g-C3N4 nanofibers, respectively. Furthermore, the ultra-long one-dimensional network structure of W18O49/C@g-C3N4 nanofibers enables easy recycling after liquid reactions. This study presents a novel approach for customizing band structures and unique surface morphology to improve synchronous dual-functional photocatalytic activity.

A transparent superhydrophobic coating on wood-based panel surfaces

ABSTRACT A transparent, environmentally friendly and durable superhydrophobic coating preparation process was developed to effectively isolate water molecules in the air, aiming to reduce the use limitations of the wood-based panel substrate and to realize its improved performance in terms of water resistance, stain resistance and durability. This study employs a coating method to apply a silica sol-modified nanocellulose (CNF) and polyvinyl alcohol (PVA) solution onto a wood-based panel substrate, creating a micro-nano rough structure. Subsequently, the vapor deposition method was employed to functionalize the silanol groups on the coating surface, resulting in the formation of fluorinated alkyl groups and achieving transparent superhydrophobic wood-based panels. The water contact angle measures 152.6°, the rolling angle was 4.5°, and the coating exhibits a light transmittance of 92%. Notably, the superhydrophobicity of the coating persists even after repeated polishing paper abrasion, demonstrating excellent anti-pollution self-cleaning properties. This study is of great significance for the long-term use of wood-based panels indoors and outdoors, as well as their application in complex and high humidity environments.

Performance and Degradation of Electrolyte Supported SOECs with Advanced Thin-Film Gadolinium Doped Ceria Barrier Layers in Long-Term Stack Test

Electrolyte supported Solid Oxide Cells (ESCs) with advanced thin-film Gd-doped ceria diffusion barrier layers between electrolyte and electrodes were assembled and electrochemically investigated in steam electrolysis mode in a so-called “rainbow” stack with 30 repeat units (RUs). The barrier layers were deposited onto the electrolyte supports via electron-beam physical evaporation deposition (EB-PVD) method at 600 °C. In this paper, the investigation mainly focuses on the electrochemical characteristics of RUs containing the EB-PVD thin-film GDC layers. At the initial stage of the SOEC operation, the stack reached a high performance with an electrical efficiency of 99.65% at 75% steam conversion and a total power input of 1.98 kW. A long-term stack test was performed in SOEC mode for over 5000 h and demonstrated a low voltage degradation of approx. +11.3 mV·kh–1 per RU (+0.9% kh–1). The RUs with EB-PVD GDC thin-films revealed similar initial performance and degradation rate to the state-of-the-art cells with screen printed GDC layers.

Continuous-Wave Pumped Monolayer WS2 Lasing for Photonic Barcoding.

Micro/nano photonic barcoding has emerged as a promising technology for information security and anti-counterfeiting applications owing to its high security and robust tamper resistance. However, the practical application of conventional micro/nano photonic barcodes is constrained by limitations in encoding capacity and identification verification (e.g., broad emission bandwidth and the expense of pulsed lasers). Herein, we propose high-capacity photonic barcode labels by leveraging continuous-wave (CW) pumped monolayer tungsten disulfide (WS2) lasing. Large-area, high-quality monolayer WS2 films were grown via a vapor deposition method and coupled with external cavities to construct optically pumped microlasers, thus achieving an excellent CW-pumped lasing with a narrow linewidth (~0.39 nm) and a low threshold (~400 W cm-2) at room temperature. Each pixel within the photonic barcode labels consists of closely packed WS2 microlasers of varying sizes, demonstrating high-density and nonuniform multiple-mode lasing signals that facilitate barcode encoding. Notably, CW operation and narrow-linewidth lasing emission could significantly simplify detection. As proof of concept, a 20-pixel label exhibits a high encoding capacity (2.35 × 10108). This work may promote the advancement of two-dimensional materials micro/nanolasers and offer a promising platform for information encoding and security applications.

STUDY ON FORMULATION OF BACTERIAL CELLULOSE NANOFIBERS-COATED NANOLIPOSOMES CONTAINING PACLITAXEL FOR ORAL ADMINISTRATION

Objective: The low oral bioavailability of paclitaxel (PAC) because of its limited aqueous solubility and poor intestinal permeability after being administered orally suggests the need for a sustained release system. The aim of this study is to produce and evaluate in vitro a nanoliposome system that carries paclitaxel (BCN-LIP-PAC) for oral administration. Methods: Thin-film evaporation and electrostatic deposition methods were used to obtain LIP-PAC and BCN-LIP-PAC. Particle size, polydispersity index (PDI), zeta potential, morphological analysis, entrapment efficiency percentage (EE%), and in vitro dissolution studies were used to characterize the developed systems. Results: The nano-range sizes of LIP-PAC and BCN-LIP-PAC (0.1 % BCN) were 112±4.2 nm and 154±6.4 nm, respectively, where EE % were 80.6±2.3 % and 84.6±1.7 %, respectively. BCN-LIP-PAC exhibited good stability in simulated gastrointestinal fluids. The drug release experiments conducted in vitro showed that BCN-LIP-PAC had obvious sustained release behaviors when compared to LIP-PAC. Furthermore, the release rate of PAC from all LIP-PAC and BCN-LIP-PAC was higher in SIF than in SGF. Conclusion: The preparation, characterization, and evaluation of BCN-LIP-PAC (0.1 % BCN) for oral PAC delivery were all successful. In conclusion, the approach presented herein is a promising option for delivering oral sustained-release PAC.

Nanoporous glass as prospective material for fiber optics

The method of manufacturing active silica fibers by sintering nanoporous glasses has a number of advantages over methods of vapor deposition (MCVD, OVD). The features of obtaining nanoporous glasses by the method of two-phase separation of alkali borosilicate glasses are described. Examples of doping sintered nanoporous glasses with rare earth elements are given and the main results on the production of active fibers with a core are considered. It has been shown that such fibers are similar to their MCVD analogues in terms of properties. At the same time, it is possible to impregnate nanoporous glass with large (more than 1 at.%) concentration of dopants without revealing clustering effects and without noticeable fluctuations in the refractive index of the fiber core glass.

Oxygen-doped colloidal GaN quantum dots with blue emission

Gallium nitride quantum dots (GaN QDs), as a third-generation semiconductor material, are usually synthesized through a vapor deposition method at an elevated temperature (typically ≥800 °C). Thermal injection method is rarely reported for the synthesis of GaN QDs due to the lack of active precursors and the require of harsh reaction conditions. Here, we report the fabrication of oxygen doped colloidal GaN QDs via rapid thermal injection. By screening the reaction temperature and solvent, well-dispersed GaN QDs with a size of 3.8 nm were obtained in octadecylamine (ODA) at 360 °C. The synthesized GaN QDs show blue emission, the maximum emission wavelength is about 440 nm, and the photoluminescence quantum yield is 14.3%. Furthermore, we reveal the donor-acceptor mechanism of blue emission from GaN QDs. During the growth of GaN QDs, oxygen atoms occupy some nitrogen sites and produce a shallow oxygen donor energy level (ON). A part of the ON can be combined with the adjacent gallium vacancy (VGa) to form a VGa-ON acceptor, whose energy level is about 0.98 eV above the valence band of GaN QDs. The transition of excited electrons from the donor (ON) to the acceptor (VGa-ON) is responsible for the blue emission of GaN QDs.

Diffusible Capping Layer Enabled Homogeneous Crystallization and Component Distribution of Hybrid Sequential Deposited Perovskite.

Nowadays, the development of wide-bandgap perovskite by thermal evaporation and spin-coating hybrid sequential deposition (HSD) method has special meaning on textured perovskite/silicon tandem solar cells. However, the common issues of insufficient reaction caused by blocking of perovskite capping layer are exacerbated in HSD, because evaporated precursors are usually denser with higher crystallinity and the widely used additive-assisted microstructure is also difficult to access. Here, a facile "diffusible perovskite capping layer" (DPCL) strategy to solve this dilemma is presented. With DPCL, crystallization alleviation of perovskite and more diffusion channels of organic salts can be realized simultaneously, contributing to a homogenization process. The resultant perovskite films exhibit complete conversion, uniform crystallization, enhanced quality, and reduced defect, leading to obvious improvements in device efficiency, repeatability, and stability. This work offers a way to promote the development of textured tandems a step further.

Semiconductor Properties of π‐Extended 2‐(Thiopyran‐4‐ylidene)‐1,3‐benzodithiole (TP‐BT) Analogs

AbstractDespite having an asymmetric structure, 2‐(thiopyran‐4‐ylidene)‐1,3‐benzodithiole (TP‐BT) is a good p‐type semiconductor containing isotropic three‐dimensional (3D) intermolecular interactions. Moreover, its π‐extended analogs can potentially work as organic electronic materials. Herein, a fused‐type π‐extended analog containing an extra benzene ring on the benzodithiole unit, i. e., 2‐(thiopyran‐4‐ylidene)‐1,3‐naphtho[2,3‐d]dithiole (TP‐NT), and three σ‐bonded‐type π‐extended analogs, i. e., phenyl‐, naphthyl‐, and anthryl‐substituted analogs (Ph‐TP‐BT, Nap‐TP‐BT, and Ant‐TP‐BT, respectively), were prepared and their molecular arrangements and organic field‐effect transistor (OFET) properties were investigated. TP‐NT formed a herringbone arrangement with 3D intermolecular interactions similar to that of the parent TP‐BT. Meanwhile, Ant‐TP‐BT formed a bilayer‐type layered herringbone arrangement. Since the highest occupied molecular orbital and the lowest unoccupied molecular orbital are located on the TP‐BT and anthracene units, respectively, a unique donor–acceptor separated network was formed. In OFETs prepared via a vapor deposition method using the σ‐bonded‐type analogs, slightly lower mobilities (0.1 to 8×10−3 cm2/Vs) than that of TP‐NT (0.1 cm2/Vs) were observed. Upon photo‐irradiation, the OFET of Ant‐TP‐BT exhibited a larger threshold voltage shift and an increase in the off current compared with TP‐NT. The σ‐bonded‐type analogs showed a larger photo‐response effect than TP‐NT derived from the donor–acceptor molecular structure.

Efficient Photocatalytic Cleavage of Lignin Models by a Soluble Perylene Diimide/Carbon Nitride S-Scheme Heterojunction.

3,4,9,10-Perylenetetracarboxylic dianhydride (PDI) is one of the best n-type organic semiconductors and an ideal light-driven catalyst for lignin depolymerization. However, the charge localization effect and the excessively strong intermolecular aggregation trend in PDI result in rapid electron-hole (e- -h+ ) recombination, which limits photocatalytic performance. Herein, polymeric carbon nitride/polyhedral oligomeric silsesquioxane PDI (p-CN/P-PDI) S-scheme heterojunction photocatalyst was prepared by the solvent evaporation-deposition method for C-C bond selective cleavage of lignin β-O-4 model. Based on the material characterization results, the synergic role of polyhedral oligomeric silsesquioxane (POSS) and S-scheme heterojunction maintains appropriate aggregation domains, achieves better solar light utilization, faster charge-transfer efficiency, and greater redox capacity. Notably, the 3 % p-CN/P-PDI heterostructure exhibits a remarkable enhancement in cleavage conversion efficiency, achieving approximately 16.42 and 2.57 times higher conversion rates compared to polyhedral oligomeric silsesquioxane modified PDI (POSS-PDI) and polymeric carbon nitride (p-CN), respectively.

Supported Ni Catalysts: Simple Vapor Deposition Preparation Method and Improved Catalytic Performance for Oxidative Dehydrogenation of Ethane.

Developing new methods of catalyst preparation is one of the most important tasks in the field of catalysis. A simple one-tube vapor deposition (VD) is provided in this paper for preparing the supported Ni catalyst. Ni(acac)2 was used as the Ni precursor. This preparation method was successfully applied to three types of catalytic supports, that is, Al2O3 and zeolites 5A and Hβ. Varying Ni contents of less than 8 wt % can be obtained by employing different conditions. The Ni content, depending on different deposition conditions, was preliminarily explored. The catalytic performance for oxidative dehydrogenation of ethane (ODHE) was tested for the prepared Ni catalysts by the VD method. Several cases of catalytic tests showed that for the same Ni content, the VD-prepared Ni catalyst presented better performance for ODHE than the one prepared by a traditional impregnation method. Besides the improvement in catalytic performance, several advantages of our VD preparation method for catalysis are discussed.

Performance and Degradation of Electrolyte Supported SOECs with Advanced GDC Thin-film Layers in Long-term Stack Test

Solid oxide electrolyser (SOE) based on electrolyte-supported cell (ESC) architecture is proven to be highly efficient and reliable technology for green hydrogen production via high temperature electrolysis. Operating under industrial conditions, the performance, lifetime and robustness of the cells and stacks belong to the most important factors for an up-scaled penetration of the SOE technology into energy and chemistry sectors. A typical ESC consists of scandia- or yttria-stabilized zirconia electrolyte, Ni-cermet fuel electrode, lanthanum strontium cobalt ferrite (LSCF) oxygen electrode and either one or two Gd-doped ceria (GDC) layers with a thickness of 5-7 µm between electrolyte and electrodes. At the oxygen electrode side, the GDC layer prevents interdiffusion (mainly of Sr), whereas at the fuel electrode side, the GDC layer may improve the electrode adherence to electrolyte and reduce the interfacial resistance. State-of-the-art fabrication route of the GDC layers is screen-printing followed by partially sintering at high temperature between 1200 °C to 1300 °C. This fabrication process usually results in porous structure in the GDC layers and residual stresses which reduce the mechanical strength of the cells.Aiming to improve the mechanical strength of ESCs and the properties (e.g. porosity and electrical conductivity) of GDC layers, the conventional screen-printed GDC layers either only at the oxygen electrode or at both electrodes were replaced by 0.5 µm thick thin-film GDC layers fabricated by electron-beam physical evaporation deposition (EB-PVD) method at 600 °C. These EB-PVD-fabricated thin-film GDC layers were electrochemically characterized in a so-called “rainbow” stack with 30 repeat units (RUs), including 4 RUs with EB-PVD GDC layers at the oxygen electrode and screen-printed GDC at fuel electrode, 3 RUs with EB-PVD GDC layers at both electrodes and 23 RUs with state-of-the-art screen-printed GDC layers at both electrodes. The stack was operated for over 5000 h in SOEC mode under a current density of -410 mA cm−2 and 75 % steam conversion, with a feed gas composition of 80 % steam + 10 % H2 + 10 % N2 on the fuel electrode and air on oxygen electrode.In this paper, the investigation focuses on the electrochemical characteristics of RUs containing the EB-PVD thin-film GDC layers during the SOEC stack testing. The performance and degradation behavior of the stack and representative RUs were investigated and compared by means of current-voltage curves and electrochemical impedance spectroscopy (EIS). The initial performance and the degradation of the voltage and resistances of the stack and the RUs with EB-PVD GDC thin-film layers were determined and discussed in order to evaluate the effectiveness of the modifications in the scenario of long-term SOEC stack testing.The German Federal Ministry for Education and Research (BMBF) is acknowledged for the financial supports within the project H2GiGa-HTEL (grant no. 03HY124E).

In Situ Growth Engineering on 2D MXenes for Next‐Generation Rechargeable Batteries

MXene is an emerging 2D material and shows large potential as a substrate for in situ growth of functional materials due to its merits such as large surface area, abundant nucleation sites, structural diversity, superior dispersion ability, blocking agglomeration of nanomaterials, and rich element/kind compositions. The in situ‐formed MXene‐based composites are largely applied in rechargeable batteries in the past several years by acting as active materials, serving as current collectors, decorating separators, and catalyzing electrochemical process. However, a detailed and systematic summary is still lacked. Herein, a review on in situ growth engineering on 2D MXene for next‐generation rechargeable batteries is presented in detail for the first time. Meanwhile, some outlooks and perspectives are put forward. In situ growth engineering on 2D MXenes can be achieved by calcination method, hydrothermal method, solvothermal method, room‐temperature liquid‐phase reduction method, room‐temperature liquid‐phase oxidation method, electrochemical deposition method, in situ polymerization method, vapor deposition method, mechanical milling method, microwave method, composite method, self‐reduction method, coprecipitation method, immersion method, hydrolysis method, etc. These in situ growth strategies can be extended to materials beyond MXenes, such as graphene, MBene, graphdiyne, etc.

Luminescence Properties of the Hexagonal Boron Nitride Epilayer

AbstractAs an emerging 2D ultrawide bandgap semiconductor, hexagonal boron nitride (h‐BN) is gaining significant attention for its superior properties and wide applications. Although optical properties of h‐BN have been partially revealed by using h‐BN bulk single crystal, luminescence properties of the h‐BN few‐layer are rare due to its poor crystallinity. In this work, the h‐BN epilayers have been synthesized on sapphire substrates by the submicron‐spacing vapor deposition method. The crystalline quality of the h‐BN epilayer is improved with the increase of the growth temperature, and the full width at half‐maximum of the Raman peak is only ≈13 cm−1. The low temperature cathodoluminescence spectra of h‐BN epilayers exhibit two strong deep ultraviolet (DUV) luminescence peaks at 5.49 and 5.35 eV, as well as a weaker and broader defect‐related emission band at ≈4.0 eV. The DUV emission band is ascribed to the recombination of bound excitons and its phonon replica. Based on the theoretically predicted energy levels, the 4.0 eV emission band is tentatively attributed to the radiative transition from C impurities occupying the B sites to the B vacancies. Moreover, the h‐BN‐based DUV photodetectors exhibit an outstanding performance, making it a promising prospect for optoelectronic applications.

NiFeCr–S/NiS/NF with modified 2D nanosheet array as bifunctional electrocatalysts for overall water splitting

Hetero-structured NiFeCr–S/NiS nanosheet arrays supported on nickel foam (NiFeCr–S/NiS/NF) were prepared by sulfurizing the hetero-structured hybrid of NiFeCr-layered double hydroxides/NiS/NF (NiFeCr-LDH/NiS/NF) through sequential hydrothermal method and vapour deposition method. Benefiting from the abundant NiS/NiFeCr–S interfaces and the two-dimensional nanosheet structure, the as-prepared catalyst displays an overpotential at 10 mA cm−2 of 94 mV for oxygen evolution reaction and 131 mV for hydrogen evolution reaction, respectively, which is better than the non-sulfurized NiFeCr-LDH/NiS/NF and NiFeCr-LDHs/NF, as well as the sulfurized NiFeCr–S/NF and NiS/NF. In the self-assembled device using NiFeCr–S/NiS/NF as both cathode and anode, the overall water splitting reaction can be driven at 1.53 V of cell voltage to achieve the current density of 10 mA cm−2.

Photon Upconversion in a Vapor Deposited 2D Inorganic-Organic Semiconductor Heterostructure.

Energy transfer processes may be engineered in van der Waals heterostructures by taking advantage of the atomically abrupt, Å-scale, and topologically tailorable interfaces within them. Here, we prepare heterostructures comprised of 2D WSe2 monolayers interfaced with dibenzotetraphenylperiflanthene (DBP)-doped rubrene, an organic semiconductor capable of triplet fusion. We fabricate these heterostructures entirely through vapor deposition methods. Time-resolved and steady-state photoluminescence measurements reveal rapid subnanosecond quenching of WSe2 emission by rubrene and fluorescence from guest DBP molecules at 612 nm (λexc = 730 nm), thus providing clear evidence of photon upconversion. The dependence of the upconversion emission on excitation intensity is consistent with a triplet fusion mechanism, and maximum efficiency (linear regime) of this process occurs at threshold intensities as low as 110 mW/cm2, which is comparable to the integrated solar irradiance. This study highlights the potential for advanced optoelectronic applications employing vdWHs which leverage strongly bound excitons in monolayer TMDs and organic semiconductors.

Molecular Synergistic Passivation for Efficient Perovskite Solar Cells and Self-Powered Photodetectors.

The interface between the perovskite and electron-transporting material is often treated for defect passivation to improve the photovoltaic performance of devices. A facile 4-Acetamidobenzoic acid (containing an acetamido, a carboxyl, and a benzene ring)-based molecular synergistic passivation (MSP) strategy is developed here to engineer the SnOx /perovskite interface, in which dense SnOx are prepared using an E-beam evaporation technology while the perovskite is deposited with vacuum flash evaporation deposition method. MSP engineering can synergistically passivate defects at the SnOx /perovskite interface by coordinating with Sn4+ and Pb2+ with functional group CO in the acetamido and carboxyl. The optimized solar cell devices can achieve the highest efficiency of 22.51% based on E-Beam deposited SnOx and 23.29% based on solution-processed SnO2 , respectively, accompanied by excellent stability exceeding 3000h. Further, the self-powered photodetectors exhibit a remarkably low dark current of 5.22×10-9 Acm-2 , a response of 0.53AW-1 at zero bias, a detection limit of 1.3×1013 Jones, and a linear dynamic range up to 80.4dB. This work proposes a molecular synergistic passivation strategy to enhance the efficiency and responsivity of solar cells and self-powered photodetectors.

Variation of Charge Carrier Dynamics for Polycrystalline Perovskite Films by One-Step Solution and Vapor-Deposition Methods.

To date, solution-processing and vapor-deposition fabrication methods have achieved huge successes in high-efficiency perovskite solar cells (PSCs) and satisfy special demanding requirements for diverse application purposes, respectively. Although people realize that the fabrication procedure is crucial in device performance, insightful studies of charge carrier dynamics in perovskite films by different methods still lack. In this work, we compare the carrier behaviors in one-step spin-coated and dual-source coevaporated MAPbI3 perovskite films by combining time-resolved photoluminescence spectroscopy and carrier dynamics simulation. We suggest that strains, lattice orientations, and defects at buried side of perovskite films, which are associated with different preparation processes, lead to variations in carrier behaviors. Hence fabrication of perovskite layers should be elaborately designed in order to satisfy the needs of different carrier behaviors in specified device configurations of PSCs such as smooth planar or textured monolithic tandem structures.

Epitaxial Electrodeposition of Ordered Inorganic Materials.

ConspectusThe quality of technological materials generally improves as the crystallographic order is increased. This is particularly true in semiconductor materials, as evidenced by the huge impact that bulk single crystals of silicon have had on electronics. Another approach to producing highly ordered materials is the epitaxial growth of crystals on a single-crystal surface that determines their orientation. Epitaxy can be used to produce films and nanostructures of materials with a level of perfection that approaches that of single crystals. It may be used to produce materials that cannot be grown as large single crystals due to either economic or technical constraints. Epitaxial growth is typically limited to ultrahigh vacuum (UHV) techniques such as molecular beam epitaxy and other vapor deposition methods. In this Account, we will discuss the use of electrodeposition to produce epitaxial films of inorganic materials in aqueous solution under ambient conditions. In addition to lower capital costs than UHV deposition, electrodeposition offers additional levels of control due to solution additives that may adsorb on the surface, solution pH, and, especially, the applied overpotential. We show, for instance, that chiral morphologies of the achiral materials CuO and calcite can be produced by electrodepositing the materials in the presence of chiral agents such as tartaric acid.Inorganic compound materials are electrodeposited by an electrochemical-chemical mechanism in which solution precursors are electrochemically oxidized or reduced in the presence of molecules or ions that react with the redox product to form an insoluble species that deposits on the electrode surface. We present examples of reaction schemes for the electrodeposition of transparent hole conductors such as CuI and CuSCN, the magnetic material Fe3O4, oxygen evolution catalysts such as Co(OH)2, CoOOH, and Co3O4, and the n-type semiconducting oxide ZnO. These materials can all be electrodeposited as epitaxial films or nanostructures onto single-crystal surfaces. Examples of epitaxial growth are given for the growth of films of CuI(111) on Si(111) and nanowires of CuSCN(001) on Au(111). Both are large mismatch systems, and the epitaxy is explained by invoking coincidence site lattices in which x unit meshes of the film overlap with y unit meshes of the substrate.We also discuss the epitaxial lift-off of single-crystal-like foils of metals such as Au(111) and Cu(100) that can be used as flexible substrates for the epitaxial growth of semiconductors. The metals are grown on a Si wafer with a sacrificial SiOx interlayer that can be removed by chemical etching. The goal is to move beyond the planar structure of conventional Si-based chips to produce flexible electronic devices such as wearable solar cells, sensors, and flexible displays. A scheme is shown for the epitaxial lift-off of wafer-scale foils of the transparent hole conductor CuSCN.Finally, we offer some perspectives on possible future work in this area. One question we have not answered in our previous work is whether these epitaxial films and nanostructures can be grown with the level of perfection that is achieved in UHV. Another area that is ripe for exploration is the epitaxial electrodeposition of metal-organic framework materials from solution precursors.