Search

Volatile organic compounds (VOCs), particularly monoaromatic hydrocarbon compounds (MACHs), pose a potential risk to the atmospheric environment and human health. Therefore, the progressive development of efficient detection methodologies is a pertinent need, which is still a challenge at present. In this study, we present a rapid and sensitive method to detect trace amounts of MACHs using a bifunctional SERS composite substrate. We prepared an Au/SiO2 enhanced layer and a porous Cu(OH)2 adsorption layer via microfluidic-assisted gas-liquid interface self-assembly. The composite substrate effectively monitored changes in benzaldehyde using time-varying SERS spectra, and track-specifically identified various VOCs such as benzene, xylene, styrene, and nitrobenzene. In general, the substrate exhibited a rapid response time of 20 s to gaseous benzaldehyde, with a minimum detection concentration of less than 500 ppt. Further experimental assessments revealed an optimum Cu(OH)2 thickness of the surrounding adsorption layer of 150 nm, which can achieve an efficient SERS response to MACHs. Furthermore, the recoverable and reusable property of the composite substrate highlights its practicality. This study presents a straightforward and efficient approach for detecting trace gaseous VOCs using SERS, with significant implications in the designing of SERS substrates for detecting other VOCs. [ABSTRACT FROM AUTHOR]

The performance of lithium‐metal batteries is severely hampered by uncontrollable dendrite growth and volume expansion on the metal anodes. Inspired by the "blockchain" concept in data mining, here we utilize a conductive polymer‐filled metal–organic framework (MOF) as the lithium host, in which polypyrrole (PPy) serves as the "chain" to interlink Li "blocks" stored in the MOF pores. While the N‐rich PPy guides fast Li+ infiltration/extrusion and serves as the nucleation sites for isotropic Li growth, the MOF pores compartmentalize bulk Li deposition for 3D matrix Li storage, leading to low‐barrier and dendrite‐free Li plating/stripping with superb Coulombic efficiency. The as‐fabricated lithium‐metal anodes operate over 700 cycles at 5 mA cm−2 in symmetric cells, and 800 cycles at 1 C in full cells with a per‐cycle capacity loss of only 0.017 %. This work might open a new chapter for Li‐metal anode construction by introducing the concept of "blockchain" management of Li plating/stripping. [ABSTRACT FROM AUTHOR]

Electrocatalytic conversion of carbon dioxide into high‐value multicarbon (C2+) chemical feedstocks offers a promising avenue to liberate the chemical industry from fossil‐resource dependence and eventually close the anthropogenic carbon cycle but is severely impeded by the lack of high‐performance catalysts. To break the linear scaling relationship of intermediate binding and minimize the kinetic barrier of CO2 reduction reactions, ternary Cu–Au/Ag nanoframes were fabricated to decouple the functions of CO generation and C−C coupling, whereby the former is promoted by the alloyed Ag/Au substrate and the latter is facilitated by the highly strained and positively charged Cu domains. Thus, C2H4 production in an H‐cell and a flow cell occurred with high Faradic efficiencies of 69±5 and 77±2 %, respectively, as well as good electrocatalytic stability and material durability. In situ IR and DFT calculations unveiled two competing pathways for C2H4 generation, of which direct CO dimerization is energetically favored. [ABSTRACT FROM AUTHOR]

ABSTRACT To increase the encapsulation efficiency of microcapsules composed of water-soluble salt cores and hydrophobic material shells, we herein reported a facile and versatile strategy to improve the hydrophobicity of water-soluble salts [i.e., ammonium persulfate (APS)] by surface modification of APS using oleic acid or silane coupling agent, respectively. The results confirmed that the hydrophobicity of the two modified APS had been successfully improved compared with that of non-modified APS. Moreover, the two modified APS could be effectively encapsulated into hydrophobic polystyrene and the encapsulation efficiency of the resulting microcapsules goes up significantly. This study was expected to drive progress in the preparation technology of microcapsules which comprise water-soluble salts as cores and hydrophobic polymer materials as shells in many industrial application fields. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45294. [ABSTRACT FROM AUTHOR]

The deployment of Li metal batteries has been significantly tethered by uncontrollable lithium dendrite growth, especially in heavy-duty operations. Herein, we implement an in situ surface transformation tactic exploiting the vapor-phase solid-gas reaction to construct an artificial solid-electrolyte interphase (SEI) of Li 2 Se on Li metal anodes. The conformal Li 2 Se layer with high ionic diffusivity but poor electron conductivity effectively restrains the Li/Li + redox conversion to the Li/Li 2 Se interface, and further renders a smooth and chunky Li deposition through homogenized Li + flux and promoted redox kinetics. Consequently, the as-fabricated Li@Li 2 Se electrodes demonstrate superb cycling stability in symmetric cells at both high capacity and current density. The merits of inhibited dendrite growth and side reactions on the stabilized Li@Li 2 Se anode are further manifested in Li-O 2 batteries, greatly extending the cycling stability and energy efficiency.

The electroreduction of carbon dioxide (CO 2 RR) to CH 4 stands as one of the promising paths for resourceful CO 2 utilization in meeting the imminent "carbon-neutral" goal of the near future. Yet, limited success has been witnessed in the development of high-efficiency catalysts imparting satisfactory methane selectivity at a commercially viable current density. Herein, a unique category of CO 2 RR catalysts is fabricated with the yolk-shell nanocell structure, comprising an Ag core and a Cu 2 O shell that resembles the tandem nanoreactor. By fixing the Ag core and tuning the Cu 2 O envelope size, the CO flux arriving at the oxide-derived Cu shell can be regulated, which further modulates the *CO coverage and *H adsorption at the Cu surface, consequently steering the CO 2 RR pathway. Density functional theory simulations show that lower CO coverage favors methane formation via stabilizing the intermediate *CHO. As a result, the best catalyst in the flow cell shows a high CH 4 Faraday efficiency of 74 ± 2% and partial current density of 178 ± 5 mA cm - 2 at -1.2 V RHE , ranking above the state-of-the-art catalysts reported today for methane production. These findings mark the significance of precision synthesis in tailoring the catalyst geometry for achieving desired CO 2 RR performance., (© 2021 Wiley-VCH GmbH.)

Rechargeable lithium-oxygen batteries (LOBs) have attracted increasing attention due to their high energy density but highly rely on the development of efficient oxygen catalysts for reversible Li 2 O 2 deposition/decomposition. Herein, highly porous carbon nanocubes with a specific surface area up to 1600 m 2 g -1 are synthesized and utilized to tightly anchor Ru nanoparticles for using as the oxygen-cathode catalyst in LOBs, achieving a low charge/discharge potential gap of only 0.75 V, a high total discharge capacity of 17,632 mA h g -1 , and a superb cycling performance of 550 cycles at 1000 mA g -1 . Comprehensive ex situ and operando characterizations unravel that the outstanding LOB performance is ascribed to the highly porous catalyst structure embedding rich active sites that synergistically function in reducing overpotentials, suppressing parasitic reactions, accommodating reaction products, and promoting mass and charge transportation.