Droplets impact on sparse microgrooved non-wetting surfaces.

Droplets impinging on sparse microgrooved polydimethylsiloxane (PDMS) surfaces with different solid fractions was experimentally investigated. First, wettability and stability of droplets on these surfaces was analyzed. The advancing and receding contact angles were found to have a large difference between in the longitudinal direction and in the transverse one, which could be attributed to the anisotropy of the micropatterned surfaces.

Wetting and evaporation behavior of dilute sodium dodecyl sulfate droplets on soft substrates under a direct current electric field.

Wetting and evaporation behavior of dilute sodium dodecyl sulfate (SDS) droplets on planar polydimethylsiloxane (PDMS) surfaces under a direct current (DC) electric field were experimentally investigated. Two characteristic voltages-actuation voltage and saturation voltage were observed in the electrowetting of dilute SDS droplets on PDMS surfaces. It was found that for dilute SDS droplets with a fixed SDS concentration substrate elasticity has an obvious influence on actuation voltage, and saturation voltage increased with the increase of mass ratio of PDMS surfaces.

A self-sacrificing template strategy: In-situ construction of bimetallic MOF-derived self-supported CuCoSe nanosheet arrays for high-performance supercapacitors.

Transition metal selenides (TMSs) are viewed as a prospective high-capacity electrode material for asymmetric supercapacitors (ASCs). However, the inability to expose sufficient active sites due to the limitation of the area involved in the electrochemical reaction severely limits their inherent supercapacitive properties. Herein, a self-sacrificing template strategy is developed to prepare self-supported CuCoSe (CuCoSe@rGO-NF) nanosheet arrays by in situ construction of copper-cobalt bimetallic organic framework (CuCo-MOF) on rGO-modified nickel foam (rGO-NF) and rational design of Se exchange process.

Localized Electron Density Regulation Effect for Promoting Solid-Liquid Ion Adsorption to Enhance Areal Capacitance of Micro-Supercapacitors.

The development of flexible microelectronic systems requires the construction of high-energy-output planar micro-supercapacitors (MSCs). Herein, the localized electron density, by introducing graphene quantum dots (GQDs) on the surface of electrodes, is regulated. The enhanced local field intensity promotes ion electrostatic adsorption at the solid-liquid interface, which significantly improves the energy density of MSCs in the confined space.

Highly distributed amorphous copper catalyst for efficient ammonia electrosynthesis from nitrate.

Electroreduction of nitrate to ammonia, instead of N, is beneficial toward pollution control and value-added chemical production. Metallic catalysts have been developed for enhancing ammonia evolution efficiency from nitrate based on the crystalline state of the catalyst. However, the development of amorphous metallic catalysts with more active sites is still unexplored.

Evaporative Deposition of Surfactant-Laden Nanofluid Droplets over a Silicon Surface.

Morphologies of evaporative deposition, which has been widely applied in potential fields, were induced by the competition between internal flows inside evaporating droplets. Controlling the pattern of deposition and suppressing the coffee-ring effect are essential issues of intense interest in the aspects of industrial technologies and scientific applications. Here, evaporative deposition of surfactant-laden nanofluid droplets over silicon was experimentally investigated.

Dual structure engineering of SiO-acrylic yarn derived carbon nanofiber based foldable Si anodes for low-cost lithium-ion batteries.

Silicon (Si) is attracted much attention due to its outstanding theoretical capacity (4200 mAh/g) as the anode of lithium-ion batteries (LIBs). However, the large volume change and low electron/ion conductivity during the charge and discharge process limit the electrochemical performance of Si-based anodes. Here we demonstrate a foldable acrylic yarn-based composite carbon nanofiber embedded by Si@SiO particles (Si@SiO-CACNFs) as the anode material.

N, S-doped graphene derived from graphene oxide and thiourea-formaldehyde resin for high stability lithium-sulfur batteries.

Although lithium-sulfur (Li-S) batteries with a high theoretical energy density and low cost have attracted extensive research attention, their commercialization is still unsuccessful due to the poor cycle life caused by the dissolution of polysulfides. It is the key challenge to overcome polysulfide shuttling for achieving long-term cycling stability in Li-S batteries. Here we report a novel strategy for the synthesis of N, S-doped graphene with high nitrogen and sulfur contents self-assembly of graphene oxide and thiourea-formaldehyde resin and calcination.

Droplet impact on pillar-arrayed non-wetting surfaces.

Droplet impact on pillar-arrayed polydimethylsiloxane (PDMS) surfaces with different solid fractions was studied. The lower and upper limits of Weber number, We, for complete rebound of impacting droplets decreased with decreasing solid fractions. Gaps were visible during the spreading and retraction processes of bouncing droplets on the surface with a solid fraction of 0.

Author Correction: Evaporative deposition of polystyrene microparticles on PDMS surface.

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Evaporative deposition of polystyrene microparticles on PDMS surface.

Evaporation of water and ethanol/water droplets containing large polystyrene (PS) microparticles on polydimethylsiloxane (PDMS) surface was experimentally investigated. It is found that no matter with or without small addition of ethanol, a compact monolayer deposition is formed for lower microparticle concentration while mountain-like deposition for higher concentration. Since the more volatile compound (ethanol) evaporates more quickly than the less volatile compound (water), evaporation of ethanol/water mixture droplet exhibits different characteristics from pure water.

Experimental and theoretical investigations of evaporation of sessile water droplet on hydrophobic surfaces.

Experiments of sessile water droplet evaporation on both polydimethylsiloxane (PDMS) and Teflon surfaces were conducted. All experiments begin with constant contact area mode (the initial contact angle is greater than 90°), switch to constant contact angle mode and end with mixed mode. Based on the assumptions of spherical droplet and uniform concentration gradient, theoretical analyses for both constant contact area and constant contact angle modes are made and theoretical solutions are derived accordingly, especially a theoretical solution of contact angle is presented first for CCR stage with any value of the initial contact angle.

Elastic deformation of soft membrane with finite thickness induced by a sessile liquid droplet.

In this paper, the role of vertical component of surface tension of a droplet on the elastic deformation of a finite-thickness flexible membrane was theoretically analyzed using Hankel transformation. The vertical displacement at the surface was derived and can be reduced to Lester's or Rusanov's solutions when the thickness is infinite. Moreover, some simulations of the effect of a liquid droplet on a membrane with a finite thickness were made.

Deformation of PDMS membrane and microcantilever by a water droplet: comparison between Mooney-Rivlin and linear elastic constitutive models.

In this paper, we studied the role of vertical component of surface tension of a water droplet on the deformation of membranes and microcantilevers (MCLs) widely used in lab-on-a-chip and micro- and nano-electromechanical system (MEMS/NEMS). Firstly, a membrane made of a rubber-like material, poly(dimethylsiloxane) (PDMS), was considered. The deformation was investigated using the Mooney-Rivlin (MR) model and the linear elastic constitutive relation, respectively.