Ziran Ye

Cobalt sulfide aerogel prepared by anion exchange method with enhanced pseudocapacitive and water oxidation performances

This work introduces the anion exchange method into the sol-gel process for the first time to prepare a metal sulfide aerogel. A porous Co9S8 aerogel with a high surface area (274.2 m2 g-1) and large pore volume (0.87 cm3 g-1) has been successfully prepared by exchanging cobalt citrate wet gel in thioacetamide and subsequently drying in supercritical ethanol. Such a Co9S8 aerogel shows enhanced supercapacitive performance and catalytic activity toward oxygen evolution reaction (OER) compared to its oxide aerogel counterpart. High specific capacitance (950 F g-1 at 1 A g-1), good rate capability (74.3% capacitance retention from 1 to 20 A g-1) and low onset overpotential for OER (220 mV) were observed. The results demonstrated here have implications in preparing various sulfide chalcogels.

Co9S8 nanoparticle-decorated carbon nanofibers as high-performance supercapacitor electrodes

This work reported Co9S8 nanoparticle-decorated carbon nanofibers (CNF) as a supercapacitor electrode. By using a mild ion-exchange method, the cobalt oxide-based precursor nanoparticles were transformed to Co9S8 nanoparticles in a microwave hydrothermal process, and these nanoparticles were decorated onto a carbon nanofiber backbone. The composition of the nanofibers can be readily tuned by varying the Co acetate content in the precursor. The porous carbon nanofibers offered a fast electron transfer pathway while the well dispersed Co9S8 nanoparticles acted as the redox center for energy storage. As a result, high specific capacitance of 718 F g−1 at 1 A g−1 can be achieved with optimized Co9S8 loading. The assembled asymmetric supercapacitor with Co9S8/CNF as the cathode showed a high energy density of 23.8 W h kg−1 at a power density of 0.75 kW kg−1 and good cycling stability (16.9% loss over 10u2006000 cycles).

Surface enhanced Raman scattering substrates prepared by thermal evaporation on liquid surfaces

We present an effective surface-enhancement Raman scattering (SERS) substrate enabled by depositing metallic film on a liquid surface at room temperature. Thermal evaporation is used to deposit Au atoms on silicone oil surface and then form quasi-continuous films. Due to the isotropic characteristics of the liquid surface, this film consists of substantial nanoparticles with uniform diameter, which is different from films fabricated on solid substrates and can be served as an applicable substrate for SERS detection. With the assistance of this substrate, SERS signals of rhodamine 6G were significantly enhanced, the dependence between SERS spectra and film thickness was investigated. Analytical simulation results confirm the experimental observations and the superiorities of our proposed method for preparation of SERS substrate. This work provides a potential application of metallic film deposition on free-sustained surface and holds promise as an efficient sensor in rapid trace detection of small molecule analytes.

Synthesis of amorphous MoSx and MoSx/carbon nanotubes composite aerogels as effective hydrogen evolution reaction catalysts

AbstractThis work reported the preparation of amorphous MoSx aerogel and MoSx/carbon nanotubes composite aerogels by a modified epoxide addition sol–gel method. In this process, propylene epoxide scavenged the protons from a S–H-contained organic acid (dl-Mercaptosuccinic acid) and promoted the interactions between (NH4)6Mo7O24•4H2O and the functional groups in the organic acid to form a gel. The sulfur and molybdenum contained a wet gel turned into an amorphous MoSx aerogel after supercritical drying in ethanol. Carbon nanotubes can be further incorporated into the aerogel backbone, which can extend the specific surface area and alter the pore structures in the composite aerogels. Such composite aerogels showed good catalytic performance in electrochemical hydrogen evolution reactions.n MoSx aerogels can be prepared by the modified epoxide-adding method and showed good catalytic activity toward HER.HighlightsEpoxide addition method has been adopted to synthesize amorphous molybdenum sulfide aerogel.High surface area (up to 265.5u2009m2/g) and the developed pore structure (pore volume up to 0.89u2009cm3/g) have been achieved.Low overpotential and high activity toward hydrogen evolution have been observed.

Nanofluidic behavior at the interface of sectionalized hydrophobic/hydrophilic patterns in nanochannel

ABSTRACT We report a novel method to fabricate sectionalized hydrophobic/hydrophilic nanochannel. Photolithography, dry/wet etching, aligned anodic bonding and selective modification were utilized to fabricate nanochannel with four-sided surface patterns. Nanofluidic behavior was investigated by pressure driven method to study the relationship between pressure and meniscus position. Experimental results showed that evident delay happened to the flow before entering hydrophobic domain, the accumulative pressure required to pass through the hydrophobic section is significantly larger than hydrophilic section. This behavior may be attributed to the influence caused by the underlying wettability variation, especially under large surface-to-volume ratio in nanochannel.

Phase shifting mask modulated laser patterning on graphene

A one-step graphene patterning method is developed in this paper. A phase shifting mask is used to modulate incident laser beam spatially and generate graphene patterns by laser heating. Periodic graphene nanoribbon and nanomesh structures are fabricated by employing 1D and 2D phase shifting masks, respectively. The noncontact, simple procedure, easy handling and economic properties of this method make it promising towards graphene-based device fabrication.