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•Water vapor condensing on aluminum plate in presence of non-condensable gases.•Wettability-patterned tracks on condensing surface rapidly remove condensate.•Sample surface ...preparation is facile, scalable, does not add to the metal surface.•Optimal design by changing the fractional areas of dropwise/filmwise condensation.•Heat transfer improvement over 30% compared to dropwise condensation surface.
Condensation of vapor on metal surfaces has many engineering applications. We demonstrate a facile and scalable approach for accelerated removal of condensate on a vertical plate during condensation of water vapor in the presence of non-condensable gases. We use wettability-patterned superhydrophilic tracks (filmwise condensing domains) laid strategically on a mirror-finish (hydrophilic) aluminum surface that promotes dropwise condensation (DWC). The design facilitates capillary-driven condensate drainage and enhanced DWC heat transfer by reducing the departing droplet size on the DWC regions. The study offers quantitative insight on the promoting and retarding influences of the dropwise and filmwise condensation zones and their ramifications on overall heat transfer on this substrate. An optimal design has been achieved by changing the fractional area of superhydrophilic tracks with respect to the overall condenser plate surface, and optimizing rapid drainage by altering the track spatial layout. The study indicates that heat transfer improvements in excess of 30% can be achieved in this metal system even in the presence of non-condensable gases that are well known to hinder energy transport.
Two‐dimensional (2D) materials, such as graphene and boron nitride, have specific lattice structures independent of external conditions. In contrast, the structure of 2D boron sensitively depends on ...metal substrate, as we show herein using the cluster expansion method and a newly developed surface structure‐search method, both based on first‐principles calculations. The preferred 2D boron on weaker interacting Au is nonplanar with significant buckling and numerous polymorphs as in vacuum, whereas on more reactive Ag, Cu, and Ni, the polymorphic energy degeneracy is lifted and a particular planar structure is found to be most stable. We also show that a layer composed of icosahedral B12 is unfavorable on Cu and Ni but unexpectedly becomes a possible minimum on Au and Ag. The substrate‐dependent 2D boron choices originate from a competition between the strain energy of buckling and chemical energy of electronic hybridization between boron and metal.
Concerto in B flat: 2D materials usually have a specific lattice structure that is independent of external conditions. In contrast, the structure of 2D boron (red, see picture) depends on the metal substrate. On weakly interacting metals, 2D boron shows significant off‐plane buckling but on more reactive metals, it strongly favors a planar structure.
Meeting both high-frequency and high-speed requirements is essential, and the small form factor designs for the architecture of high-powered modules are acknowledged to impact their reliability in ...subsequent applications. However, conventional power modules utilizing a direct bonded copper substrate still encounter warpage issues stemming from the manufacturing process. This results in suboptimal heat dissipation after heat sink assembly, leading to a failure to meet automotive specifications for high voltage and high current resistance. To address this concern, our research proposes a thin and low warpage power module with an insulating metal substrate and a thermal interface material structural design. This aims to enhance heat dissipation capacity while maintaining low warpage and ensuring high mechanical reliability. The study employs coupling simulation technology integrating a process-oriented approach with a follow-up automotive specification power cycle reliability test. This allows for estimation of the warpage behavior caused by the power module process and the mechanical response of the solder layer within the module. To validate the accuracy and credibility of the simulation results, actual vehicle fabrication and related power cycling experiments are conducted. Furthermore, an improvement solution for the power module is proposed to offer a high industrial competitiveness of the long-term packaging reliability.
In this study, we employed the transient liquid-assisted growth (TLAG) process based on fluorine-free metal organic deposition (FF-MOD) to grow superconducting YBa2Cu3O7-δ (YBCO) films on metal ...substrates. Specifically, we examined the impact of BaCO3 decomposition on the generation of Ba-Cu-O liquid, the nucleation temperature of YBCO, and the growth orientation of YBCO. Moreover, we developed growth orientation phase diagrams for YBCO under different heating rates and oxygen partial pressures. Notably, rapid epitaxial growth was accomplished on LaMnO3 buffer layers, with YBCO growth rates surpassing 60 nm/s. Furthermore, we investigated the correlation between non-uniform reactions during the YBCO growth on metal substrates and the performance of the resulting material. Our study has significantly contributed to the advancement of high-temperature superconducting coated conductors by addressing the need for efficient and high-performance fabrication of YBCO-coated conductors, thereby providing valuable insights and guidance in this field.
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•Using TLAG-MOD, rapid preparation of YBCO films on LaMnO3 substrate is achieved, with a growth rate of up to 60 nm/s.•This paper systematically investigates the influencing factors on the decomposition of BaCO3 and its effects on the final orientation of YBCO film growth.•This work establishes a phase diagram for YBCO growth orientation, enabling flexible control and desired thin film orientation.•Researched the impact of secondary phases within YBCO films on their structure and performance.
Prussian blue analogues (PBAs) and their derivatives with tailorable physicochemical properties are ideal functional materials for chemical sensing, energy storage, and conversion. Herein, an ...innovative strategy is demonstrated to prepare PBA nanoarchitectures on various metal substrates. The interfacial redox reactions between metal cyanide ions and metal substrate result in the formation of desirable PBA nanostructures via the in situ precipitation process. Furthermore, the morphology and growth rates of PBAs can be readily regulated by changing the pH value of the reaction solution. The obtained PBA nanostructures can be transformed into the corresponding metal oxides via the simple thermal treatment. More importantly, the hollow oxide derivative manifests considerable catalytic activity with a low potential of 1.53 V to achieve the benchmark current density of 10 mA cm−2 and impressive prolonged durability over 600 h. This novel synthetic approach provides a favorable pathway to synthesize binder‐free PBAs and their derivatives on diverse metal substrates, enabling new kinds of nanoarchitectures with desirable morphology and compositions for specific applications.
A general and facile synthesis strategy is proposed for the in situ growth of diverse Prussian blue analogues on 3D metal substrates, which enables the fabrication of an efficient electrocatalyst for oxygen evolution reaction.
•A two-step Au deposition improved the reflectivity while retaining the low resistivity is demonstrated.•The AuGeNi/Au(1)/Au(2) (70 nm/30 nm/100 nm) Ohmic contact to N-AlGaAs with a low resistivity ...of 4.65 × 10−6 Ω·cm2 and a high reflectivity of 93.11 % at 850 nm have been obtained after RTP 420 °C for 1 min.•The LOP of IRLED with AuGeNi/Au(1)/Au(2)/Cu (70 nm/30 nm/100 nm/45 μm)composite metal substrate is 89.2 % higher than that of GaAs substrate at 300mA current.
Substrate transfer technology is a common way to prepare high-power infrared light emitting diode (IRLED), which seriously affects the photoelectric performance and reliability of LED. In this paper, a preparation technology of LED with composite metal substrate is presented. Based on electroplating and electron beam evaporation, AuGeNi/Au(1)/Au(2)/Cu composite metal substrate with thickness of 70 nm/30 nm/100 nm/45 μm was prepared, and low resistivity of 4.65 × 10−6 Ω⋅cm2 and high reflectance of 91.3 % were obtained. Compared with the original GaAs substrate, the light output power (LOP) of electroluminescence is increased by 89.2 % at the current of 300 mA.
A high-performance vertically injected broadband UV-to-IR photodetector based on Gd-doped ZnO nanorods (NRs)/CH3NH3PbI3 perovskite heterojunction was fabricated on metal substrates. Our ...perovskite-based photodetector is sensitive to a broad spectral range, from ultraviolet to infrared light region (λ = 250–1357 nm). Such structure leads to a high photoresponsivity of 28 and 0.22 A/W, for white light and IR illumination, respectively, with high detectivity values of 1.1 × 1012 and 9.3 × 109 Jones. Optical characterizations demonstrate that the IR detection is due to intraband transition in the perovskite material. Metal substrate boosts carrier injection, resulting in higher responsivity compared to the conventional devices grown on glass, whereas the presence of Gd increases the ZnO NRs performance. For the first time, the perovskite-based photodetector is demonstrated to extend its detection capability to IR (>1000 nm) with high room temperature responsivity across the detected spectrum, leading to a high-performance ingenious cost-effective UV-to-IR broadband photodetector design for large-scale applications.
Anomalous, or “excitonic” mean values (EMV) corrections to the Coulomb repulsion effects on electronic and electron-phonone characteristics of the epitaxial single-layer and carbine are studied. It ...is demonstrated that in-plane and in-chain EMV correction to the nearest neighbor electron hopping energy is small, while for the Coulomb interaction between these nanostructures and metallic substrate can be significant. This conclusion can be applied to some other carbon nanostructures.
•The role of the anomalous “excitonic” mean values (EMV) in the interatomic Coulomb repulsions is studied.•Account of EMV is significant for the graphene - substrate coupling but plays small role for the in-plane coupling in graphene.•The general results obtained for graphene are also qualitatively valid for the epitaxial carbyne.
The electrochemical CO2 reduction reaction (CO2RR) is a promising strategy to achieve electrical‐to‐chemical energy storage while closing the global carbon cycle. The carbon‐supported single‐atom ...catalysts (SACs) have great potential for electrochemical CO2RR due to their high efficiency and low cost. The metal centers’ performance is related to the local coordination environment and the long‐range electronic intercalation from the carbon substrates. This review summarizes the recent progress on the synthesis of carbon‐supported SACs and their application toward electrocatalytic CO2 reduction to CO and other C1 and C2 products. Several SACs are involved, including MNx catalysts, heterogeneous molecular catalysts, and the covalent organic framework (COF) based SACs. The controllable synthesis methods for anchoring single‐atom sites on different carbon supports are introduced, focusing on the influence that precursors and synthetic conditions have on the final structure of SACs. For the CO2RR performance, the intrinsic activity difference of various metal centers and the corresponding activity enhancement strategies via the modulation of the metal centers’ electronic structure are systematically summarized, which may help promote the rational design of active and selective SACs for CO2 reduction to CO and beyond.
This review summarizes the recent work on the synthesis of carbon‐supported single‐atom catalysts (SACs) and their application in electrochemical CO2 reduction to produce CO and other C1 and C2 products. Several different types of carbon‐supported SACs are involved, including MNx catalysts, heterogeneous molecular catalysts, and the covalent organic frameworks (COFs) based single atoms.
Single Atom Catalysts (SAC) in graphene have been recently gaining more and more attention. They are usually non-noble transition metal (TM) adatoms getting trapped at the carbon vacancies during the ...fabrication of the graphene layer, which then act as active centers for catalysis and adsorption. In this work we present a systematic and comparative investigation, by means of dispersion–corrected density functional theory (DFT) calculations, of Fe, Co, Ni, and Cu as possible SACs when they become trapped at graphene C vacancies. The stability of these TM atoms is further increased by introducing pyridinic nitrogen (N) atoms and transforming graphene into a giant porphyrin-like macrocyclic ligand. The structural, electronic and energetics properties of these systems, even under the effect of a metal substrate (weakly interacting Cu (111) or strongly interacting Ni (111)), are comparatively examined in great detail by means of crystal/ligand field theories and through ad-hoc energy decomposition analysis to highlight trends and peculiar behaviors. The position of the TM d-orbitals with respect to the Fermi level of the whole system is of considerable importance for designing prospective device applications in catalysis, electrocatalysis and sensors. To this purpose, we also examine how the reactivity of the SACs in graphene towards the hydrogen evolution reaction (HER) can be tuned with N-doping and with different substrates.
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•N-doped defective graphene is a porphyrin-like extended macrocyclic ligand.•TM atoms acquire a pseudo-square planar coordination structure.•TM atoms bind more strongly to graphene (especially when N-doped) than to the underlying support.•Increasing atomic number (Fe, Co, Ni, Cu) characterizes the position of d-states with respect to Fermi level.•Co atoms trapped in N-doped graphene, especially on Ni(111), are the most promising SACs for HER.
