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The development of facile and versatile strategies for thin-film and particle engineering is of immense scientific interest. However, few methods can conformally coat substrates of different composition, size, shape, and structure. We report the one-step coating of various interfaces using coordination complexes of natural polyphenols and Fe(III) ions. Film formation is initiated by the adsorption of the polyphenol and directed by pH-dependent, multivalent coordination bonding. Aqueous deposition is performed on a range of planar as well as inorganic, organic, and biological particle templates, demonstrating an extremely rapid technique for producing structurally diverse, thin films and capsules that can disassemble. The ease, low cost, and scalability of the assembly process, combined with pH responsiveness and negligible cytotoxicity, makes these films potential candidates for biomedical and environmental applications.

A self-terminating rapid electrodeposition process for controlled growth of platinum (Pt) monolayer films from a K 2 PtCl 4 -NaCl electrolyte has been developed that is tantamount to wet atomic layer deposition. Despite the deposition overpotential being in excess of 1 volt, Pt deposition was quenched at potentials just negative of proton reduction by an alteration of the double-layer structure induced by a saturated surface coverage of underpotential deposited H (H upd ). The surface was reactivated for further Pt deposition by stepping the potential to more positive values, where H upd is oxidized and fresh sites for the adsorption of PtCl 4 2- become available. Periodic pulsing of the potential enables sequential deposition of two-dimensional Pt layers to fabricate films of desired thickness, relevant to a range of advanced technologies.

In this paper we propose and analyze a (temporally) third order accurate exponential time differencing (ETD) numerical scheme for the no-slope-selection (NSS) equation of the epitaxial thin film growth model, with Fourier pseudo-spectral discretization in space. A linear splitting is applied to the physical model, and an ETD-based multistep approximation is used for time integration of the corresponding equation. In addition, a third order accurate Douglas-Dupont regularization term, in the form of - A Δ t 2 ϕ 0 ( L N ) Δ N 2 ( u n + 1 - u n ) , is added in the numerical scheme. A careful Fourier eigenvalue analysis results in the energy stability in a modified version, and a theoretical justification of the coefficient A becomes available. As a result of this energy stability analysis, a uniform in time bound of the numerical energy is obtained. And also, the optimal rate convergence analysis and error estimate are derived in details, in the ℓ ∞ ( 0 , T ; H h 1 ) ∩ ℓ 2 ( 0 , T ; H h 3 ) norm, with the help of a careful eigenvalue bound estimate, combined with the nonlinear analysis for the NSS model. This convergence estimate is the first such result for a third order accurate scheme for a gradient flow. Some numerical simulation results are presented to demonstrate the efficiency of the numerical scheme and the third order convergence. The long time simulation results for ε = 0.02 (up to T = 3 × 10 5 ) have indicated a logarithm law for the energy decay, as well as the power laws for growth of the surface roughness and the mound width. In particular, the power index for the surface roughness and the mound width growth, created by the third order numerical scheme, is more accurate than those produced by certain second order energy stable schemes in the existing literature.

Recent work on Cu 2− x Se has caused strong interest in this material due to its high reported peak zT (1.5) and the reduction of thermal conductivity through the mechanism of liquid-like suppression of heat capacity. In the 1960s, 3M patented Cu 1.97 Ag 0.03 Se as “TPM-217.” Over the following decade it was tested and developed by the 3M Corporation, at the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory, Teledyne Energy Systems, and the General Atomics Corporation for use as a next-generation thermoelectric material. During these tests, extreme problems with material loss through Se vaporization and chemical reactions between the material and the device contacts were found. These problems were especially severe while operating under conditions of high iL / A . As a result, the material system was abandoned. The results of these reports are discussed. A simple test of degradation of Cu 2 Se under conditions of applied current and thermal gradient was performed and showed results compatible with the work done by General Atomics.

Recent technological innovations, such as material printing techniques and surface functionalization, have significantly accelerated the development of new free-form sensors for next-generation flexible, wearable, and three-dimensional electronic devices. Ceramic film sensors, in particular, are in high demand for the production of reliable flexible devices. Various ceramic films can now be formed on plastic substrates through the development of low temperature fabrication processes for ceramic films, such as photocrystallization and transferring methods. Among flexible sensors, strain sensors for precise motion detection and photodetectors for biomonitoring have seen the most research development, but other fundamental sensors for temperature and humidity have also begun to grow. Recently, flexible gas and electrochemical sensors have attracted a lot of attention from a new real-time monitoring application that uses human breath and perspiration to accurately diagnose presymptomatic states. The development of a low-temperature fabrication process of ceramic film sensors and related components will complete the chemically stable and reliable free-form sensing devices by satisfying the demands that can only be addressed by flexible metal and organic components.

Manganese oxide (MnOx) on the surface of the filter material can be used to effectively remove ammonium (NH4+) and manganese ions (Mn2+) from water, but overgrow oxide film gradually shortens backwashing interval after several years of long-term filtration system operation. Different influent pollutant loading result in different durations for chemical peeling film. A growth kinetics model for MnOx was established by adjusting the different initial concentrations of Mn2+ in the influent, which provided a theoretical basis for determining a specific time point for film peeling and recovered the shortened backwashing intervals in the filter columns. The variation in film thickness demonstrated a linear dependence on time, confirming the high accuracy of the kinetics model for film growth. The pseudo-first-order kinetic model better fits among adsorption and oxidation kinetic models of Mn2+. Hydrogen peroxide (H2O2) was identified as an effective agent in the chemical peeling film process. Hydroxyl radicals, generated by H2O2, destroy coordination bonds, producing extremely low solubility (≡MnO2), which was then removed during the backwashing process.

Detailed understanding of growth mechanisms in organic thin-film deposition is crucial for tailoring growth morphologies, which in turn determine the physical properties of the resulting films. For growth of the rodlike molecule para-sexiphenyl, the evolution of terraced mounds is observed by atomic force microscopy. Using methods established in inorganic epitaxy, we demonstrate the existence of an additional barrier (0.67 electron volt) for step-edge crossing--the Ehrlich-Schwoebel barrier. This result was confirmed by transition state theory, which revealed a bending of the molecule at the step edge. A gradual reduction of this barrier in the first layers led to an almost layer-by-layer growth during early deposition stage. The reported phenomena are a direct consequence of the complexity of the molecular building blocks versus atomic systems.

Relieving the stress or strain associated with volume change is highly desirable for high‐performance SiOx anodes in terms of stable solid electrolyte interphase (SEI)‐film growth. Herein, a Si‐valence gradient is optimized in SiOx composites to circumvent the large volume strain accompanied by lithium insertion/extraction. SiOx@C annealed at 850°C has a gentle Si‐valence gradient along the radial direction and excellent electrochemical performances, delivering a high capacity of 506.9 mAh g−1 at 1.0 A g−1 with a high Coulombic efficiency of ~99.8% over 400 cycles. Combined with the theoretical prediction, the obtained results indicate that the gentle Si‐valence gradient in SiOx@C is useful for suppressing plastic deformation and maintaining the inner connection integrity within the SiOx@C particle. Moreover, a gentle Si‐valence gradient is expected to form a stress gradient and affect the distribution of dangling bonds, resulting in local stress relief during the lithiation/delithiation process and enhanced Li‐ion kinetic diffusion. Furthermore, the lowest interfacial stress variation ensures a stable SEI film at the interface and consequently increases cycling stability. Therefore, rational design of a Si‐valence gradient in SiOx can provide further insights into achieving high‐performance SiOx anodes with large‐scale production. It is highly desirable to develop a novel internal‐stress‐relief strategy to suppress SiOx expansion via design and optimization of Si valence in SiOx composites for high‐energy‐density lithium‐ion batteries. In our work, enhanced electrochemical performances of SiOx are obtained via optimizing the Si‐valence gradient from the viewpoint of stress evolution upon cycling.

The kinetic roughening of polymer films grown by vapor deposition polymerization was analyzed using the widely accepted classification framework of “generic scaling ansatz” given for the structure factor. Over the past two decades, this method has played a pivotal role in classifying diverse forms of dynamic scaling and understanding the mechanisms driving interface roughening. The roughness exponents of the polymer films were consistently determined as α=1.25±0.09, αloc=0.73±0.02, and αs=0.99±0.06. However, the inability to unambiguously assign these roughness exponent values to a specific scaling subclass prompts the proposal of a practical alternative. This report illustrates how all potential dynamic scaling can be consistently identified and classified based on the relationship between two temporal scaling exponents measured in real space: the average local slope and the global slope of the interface. The intrinsic anomalous roughening class is conclusively assigned to polymer film growth characterized by anomalous “native (background slope-removed) local height fluctuations”. Moreover, the new analysis reveals that interfaces exhibiting anomalous scaling, previously classified as intrinsic anomalous roughening, could potentially belong to the super-rough class, particularly when the spectral roughness exponent αs is equal to 1.

We present a linear iteration algorithm to implement a second-order energy stable numerical scheme for a model of epitaxial thin film growth without slope selection. The PDE, which is a nonlinear, fourth-order parabolic equation, is the L 2 gradient flow of the energy ∫ Ω - 1 2 ln 1 + | ∇ ϕ | 2 + ϵ 2 2 | Δ ϕ ( x ) | 2 d x . The energy stability is preserved by a careful choice of the second-order temporal approximation for the nonlinear term, as reported in recent work (Shen et al. in SIAM J Numer Anal 50:105–125, 2012 ). The resulting scheme is highly nonlinear, and its implementation is non-trivial. In this paper, we propose a linear iteration algorithm to solve the resulting nonlinear system. To accomplish this we introduce an O ( s 2 ) (with s the time step size) artificial diffusion term, a Douglas-Dupont-type regularization, that leads to a contraction mapping property. As a result, the highly nonlinear system can be decomposed as an iteration of purely linear solvers, which can be very efficiently implemented with the help of FFT in a collocation Fourier spectral setting. We present a careful analysis showing convergence for the numerical scheme in a discrete L ∞ ( 0 , T ; H 1 ) ∩ L 2 ( 0 , T ; H 3 ) norm. Some numerical simulation results are presented to demonstrate the efficiency of the linear iteration solver and the convergence of the scheme as a whole.