ACS Applied Materials & Interfaces最新文献

Redox cycling (RC) amplification has been introduced as an efficient strategy to enhance signals in electrochemical sensing at low analyte concentrations of relevant biomarkers such as dopamine. RC amplification requires closely spaced and electrically separate electrodes, preferably with nanogaps. The aim of this study was to establish a method enabling the microfabrication of carbon-based stacked-layer nanogap electrodes (SLNE) designed for RC amplification. Pyrolytic carbon was employed as the electrode material and Al₂O₃ deposited by atomic layer deposition as the insulating layer in between the two electrodes. SLNE with 89 nm nanogaps were realized without the need for high-resolution lithography methods, and access to the bottom generator electrode was enabled by dry etching of the insulating layer. Electrical separation between collector and generator electrodes was confirmed using resistance measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. Different SLNE designs and redox cycling modes were investigated in terms of capacitive background current, amplification factors, and collection efficiency using the neurotransmitter dopamine as model analyte. A redox cycling mode, here termed differential chronoamperometry (DCA) combining chronoamperometry with differential cyclic voltammetry, was proposed to minimize the effect of background current drift while still operating with steady-state currents. With DCA, a limit of detection (LOD) of 21 nM, a sensitivity of 83 nA μM^-1, a linear range from 25 nM to 10 μM, and actual detection at low concentrations of 25 nM were demonstrated for dopamine.

Gel foam is vital to its applications but remains a challenge. Herein, microbial gel foam was developed for coal spontaneous combustion, which was a gel foam loaded O₂-consuming microbial community. The microbial gel foam had the ability to consume O₂ and produce CO₂. The O₂ consumption was 94.46%, and the percentage of CO₂ reached 48.88% at 250 h. The relative abundance of Enterobacteriaceae and Candida was 93-98% and 73-77% in the upper gel foam and the bottom liquid of microbial gel foam at 240 h, respectively. Fungal in the O₂-consuming microbial community has stronger environmental tolerance than the bacterial, which was more suitable for loading in gel foam. Although the gel foam would collapse and deform, some flagellated microorganisms in the gel foam sealed the pores caused by the collapse of the foam. The "inert gas-foam layer" was formed by microorganisms at the junction of the foam and bottom liquid, which was conducive to the oxygen isolation function of the gel foam. Our results could be helpful in understanding the spatial structure of microbial gel foam and developing microbial gel foam with strong O₂ consumption.

Solid polymer electrolytes (SPEs) have gained tremendous attention because they are expected to solve the safety problems caused by liquid electrolytes. However, the low ion-transport capacity, insufficient mechanical strength, and unsatisfying flame-retardant properties greatly limit their further application. Here, we designed a poly(ethylene oxide) (PEO)-based SPE by introducing a calcium alginate (CA) nanofiber membrane obtained by electrospinning as a framework. The abundant C═O and -OH groups in the CA macromolecules not only effectively weakened the coordination environment of lithium ions (Li⁺) but also promoted the dissociation of LiTFSI, assisting in the transfer of Li⁺ along PEO polymer chains and providing an effective pathway for Li⁺ transfer. The introduction of calcium ions (Ca⁺) during the cross-linking process improved the flame-retardant property of the SPE. The obtained SPE exhibited a high ion conductivity (3.86 × 10^-4 S cm^-1, 30 °C), excellent mechanical strength (2.01 MPa), and a wide electrochemical window (5.32 V). The assembled lithium-symmetric battery could undergo stable lithium plating/stripping for 3000 h at 30 °C. Meanwhile, LiFePO₄ (LFP)/Li all-solid-state lithium metal battery showed excellent cycle stability over 300 cycles with a high discharge capacity (141.2 mAh g^-1) and retention rate (92.5%) at 0.3 and 30 °C.

The global emphasis on sustainable technologies has become a paramount concern for nations worldwide. Specifically, numerous sustainable methods are being explored as promising alternatives to the well-established vapor-compression technologies in cooling and heating devices. One such avenue gaining traction within the scientific community is the elastocaloric (eC) effect. This phenomenon holds promise for efficient cooling and heating processes without causing environmental harm. Studies carried out at the nanoscale have demonstrated the efficiency of the eC effect, proving to be comparable to that of state-of-the-art macroscopic systems. In this study, we used classical molecular dynamics simulations to investigate the elastocaloric effect for the recently synthesized γ-graphyne. Our analysis goes beyond obtaining changes in eC temperature and the coefficient of performance (COP) for two species of γ-graphyne nanoribbons (armchair and zigzag). We also explore their dependence on various conditions, including whether they are deposited on a substrate or prestrained. Our findings reveal a substantial enhancement in the elastocaloric effect for γ-graphyne nanoribbons when subjected to prestrain, amplifying it by at least 1 order of magnitude. Under certain conditions, the changes in the eC temperature and the COP of the structures reach expressive values as high as 224 K and 14, respectively. We discuss the implications of these results by examining the shape and behavior of the carbon-carbon bond lengths within the structures.

In recent years, polysaccharides have emerged as a promising alternative for the development of environmentally friendly materials. Polysaccharide-based materials have been mainly studied for applications in the food, packaging, and biomedical industries. However, many investigations report processing routes and treatments that enable the modification of the inherent properties of polysaccharides, making them useful as materials for energy applications. The control of the ionic and electronic conductivities of polysaccharide-based materials allows for the development of solid electrolytes and electrodes. The incorporation of conductive and semiconductive phases can modify the permittivities of polysaccharides, increasing their capacity for charge storage, making them useful as active surfaces of energy harvesting devices such as triboelectric nanogenerators. Polysaccharides are inexpensive and abundant and could be considered as a suitable option for the development and improvement of energy devices. This review provides an overview of the main research work related to the use of both common commercially available polysaccharides and local native polysaccharides, including starch, chitosan, carrageenan, ulvan, agar, and bacterial cellulose. Solid and gel electrolytes derived from polysaccharides show a wide range of ionic conductivities from 0.0173 × 10^-3 to 80.9 × 10^-3 S cm^-1. Electrodes made from polysaccharides show good specific capacitances ranging from 8 to 753 F g^-1 and current densities from 0.05 to 5 A g^-1. Active surfaces based on polysaccharides show promising results with power densities ranging from 0.15 to 16 100 mW m^-2. These investigations suggest that in the future polysaccharides could become suitable materials to replace some synthetic polymers used in the fabrication of energy storage devices, including batteries, supercapacitors, and energy harvesting devices.

In this study, we investigate the spin-momentum locking phenomenon on Rashba states of antimony (Sb) films. Utilizing spin pumping in conjunction with an external charge current, we uncover the topological properties of Sb surface states. Our key finding is the precise manipulation of the direction and magnitude of the charge current generated by the inverse Rashba-Edelstein effect. This control is achieved through the dynamic interaction between out-of-equilibrium pumped spins and spin-momentum-locked flowing spins, which are perpendicular to the charge current. Our results highlight Sb as a promising material for both fundamental and applied spintronics research. The studied Sb nanostructures demonstrate potential for the development of low-power logic gates operating with currents in the microampere range, paving the way for advanced spintronic applications.