Shusen Peng

A cellulose sponge with robust superhydrophilicity and under-water superoleophobicity for highly effective oil/water separation

We fabricate a cellulose sponge with stable superoleophobicity (θoil > 150°) under water and superhydrophilic wettability (θwater ≈ 0°) under oil without any further chemical modification for oil–water emulsion separation. The cellulose sponge shows superoleophobicity to various oils under water and possesses stable superoleophobicity in corrosive liquids like strong acid, alkali and salt solution. The sponge is made from the dissolution and regeneration of cellulose powder which is green, low cost, simple and easy to scale up. The natural hydrophilicity of the cellulose ensures its excellent under-water superoleophobicity and antifouling properties. The double layer construction of different pore sizes, which contains a top-layer with a pore size lower than 1 μm and a sub-layer with a pore size larger than 3 μm, ensures that the oil phase is resisted and the water phase easily and quickly permeates the sponge. Our cellulose sponge can separate oil–water mixtures, with >99.94% separation efficiency, solely using gravity and has excellent antifouling properties.

Fabrication and Investigation the Microtribological Behaviors of Ionic Liquid–Graphene Composite Films

A novel thin composite film, which contained both ionic liquids (ILs) and graphene, was fabricated successfully on silicon substrate using a dip-coating method. The formation and surface properties of the films were analyzed using scanning electron microscopy (SEM) and multifunctional X-ray photoelectron spectroscopy. A ball-on-plate tribometer was used to evaluate the influence of graphene content on the microtribological performance of the thin composite films. The results showed that compared to the single IL film deposited directly on the silicon surface, the as-prepared IL–graphene (IL-G) film showed improved friction reduction properties, which was attributed to the synergistic effect of IL and graphene. The composite IL-G film also exhibited decreasing wear resistance compared to the single IL film. We postulate that this is due to the fact that IL films become more discontinuous with the incorporation of graphene powder. This was verified by SEM imaging, which showed that the film was not continuous enough to prevent direct contact between the steel ball counterpart and Si surface.

Preparation of anticorrosion hybrid silica sol–gel coating using Ce(NO3)3 as catalyst

In this report, hybrid silica sol–gel coating was prepared using Ce(NO3)3 (Sol-Ce) as catalyst. Structure, surface morphology and anticorrosion ability of Sol-Ce solution/coating were studied by infrared spectroscopy (IR), scanning electron microscopy, energy dispersive spectrometer (EDS), potentiodynamic scan (PDS) and electrochemical impedance spectroscopy (EIS). IR results showed that Ce(NO3)3 had a stronger influence on reactivity of alkoxysilane. EDS results revealed that the fraction of Fe in Sol-Ce coating was significantly lower than regular acid-catalyzed hybrid silica sol–gel coating (Sol-Ac) and Sol-Ac with Ce(NO3)3-doped coating (Sol-Ac/Ce). The results of PDS and EIS demonstrated that Sol-Ce coating had better anticorrosion ability than Sol-Ac and Sol-Ac/Ce on carbon steel. The enhanced anticorrosion performance of the Sol-Ce coating might result from the following two reasons: (a) Ce(NO3)3 as a catalyst could alleviate the negative effects of low pH with using acid catalyst (dissolution of carbon steel) and (b) Ce(NO3)3 could impede corrosion of carbon steel as corrosion inhibitor.

Designing environmentally benign modified silica resin coatings with biomimetic textures for antibiofouling

Siloxane modified acrylic resin coatings with positive and negative replication textures were successfully fabricated by biomimicking the surface structures of natural lotus leaf and white crab shell via a replication method. The physical and chemical properties of the as-prepared coatings were systematically characterized by FT-IR spectroscopy, SEM, AFM and contact angle measurements. Moreover, the antifouling (AF) property of the biomimetic textured surfaces was tested via the settlement assay with two microalgae of different sizes. The results indicated that the micromastoids and microdimples of the lotus leaf and white crab shell could significantly inhibit the settlement of microalgae. Both biomimetic textured coatings with positive and negative lotus leaf morphology can reduce 73% attachment of Closterium and 74% attachment of Navicula. Both biomimetic textured coatings with positive and negative white crab shell morphology could reduce over 65% attachment of Closterium and Navicula. Different antifouling mechanisms of the biomimetic textured coatings were analyzed based on three key factors, including surface wettability, morphology, and algae size.

Novel functional hybrid silica sol–gel coating for copper protection via in situ thiol–ene click reaction

A novel anticorrosion coating, which crosslinks with inorganic bonds (Si–O–Si) and organic bonds (C–S–C), is prepared on copper through an in situ sol–gel method and thiol–ene click reaction. The hybrid sol solution containing mercapto and vinyl groups (MVFS) is prepared from hydrolysis and condensation of vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and 3-mercaptopropyltrimethoxysilane (MPMS). The thiol–ene click reaction was initiated with a thermal initiator after the sol solution was applied on the copper surface. Various corresponding methods are carried out to investigate this novel coatings properties. Experimental results demonstrate that the formation of organic crosslinking bonds deriving from thiol–ene click reaction can enhance the protection performance of the MVFS material for copper.

Comparative anti-corrosion properties of alkylthiols SAMs and mercapto functional silica sol–gel coatings on copper surface in sodium chloride solution

In this paper, we tried to fabricate a compact and thick mercapto functional silica sol–gel coating to achieve excellent corrosion resistance performance on copper. A detailed comparative study of alkylthiol self-assembled monolayers (SAMs) and mercapto functional silica sol–gel coating prepared by 1-octanethiol, n-dodecanethiol and (3-mercaptopropyl)trimethoxysilane (MPTMS) was carried out. The elements composition and chemical bonding of the protective coatings were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. In addition, the cross section morphologies of Cu–MPTMS sol–gel coating were investigated by field emission scanning electron microscopy. The wettability of various coatings was investigated by contact angle measurement instrument. Finally, the anti-corrosion ability of the coatings was characterized using an electrochemical workstation. Results demonstrated that compared to other alkylthiol SAMs, the Cu–MPTMS sol–gel coating showed the best anti-corrosion property in sodium chloride solution because it owned a multiple hierarchic Si–O–Si network structure, thus to achieve a higher range of thickness and lengthen the diffusion path way of corrosive medium. It was also found that compact and thick mercapto functional silica sol–gel coating shows better corrosion resistance performance than other SAMs of the same type.

A novel and facile strategy to inhibit corrosion: thiol-click synthesis of polythiols and their skinning on a metal surface to form super thick protective films

Small molecule inhibitors only form thin films that are composed of a single molecule layer or multiple molecule layers. Polymer inhibitors also cannot form thick or stable films due to the lack of crosslinking. Thus, these inhibitors are unable to provide robust protection for copper against corrosion. Inspired by the “skinning” phenomenon that is often met during the use of polythiol curing agents, we developed a novel and facile strategy that involves the skinning of polythiols on copper to form super thick protective films. Three types of polythiols, named SPT, TPT and LTPT, were prepared via thiol-click chemistry. Upon immersing bare copper into the solutions of the polythiols, Cu–S bonds immediately form to anchor the polythiol chains firmly on the copper surface, and the following Cu2+ catalysed S–S bond formation reaction leads to crosslinking and film formation. For SPT, TPT and LTPT, the film thicknesses were 2.03, 1.16 and 2.88 μm, and a very high inhibition efficiency of 99.81%, 99.96% and 99.68%, respectively, was achieved in 60 min. Neutral salt spray experiments demonstrated that the polythiol films provide excellent protection for over one week, whereas the control copper samples employing benzotriazole and 1-dodecanethiol suffered from severe corrosion in only 4 h. SPT and TPT have a storage problem due to their instability in air, but this problem was solved by using stable LTPT containing latent thiol groups.

Ni–P synergetic deposition: electrochemically deposited highly active Ni as a catalyst for chemical deposition

The nucleation mechanism of the preparation of a Ni–P deposit by the synergetic effect of electrochemical deposition and chemical deposition was studied using an electrochemical analysis method. Cathode polarization and chronoamperometry were performed to explore the effect of the reducing reaction (chemical deposition) on the electrochemical Ni deposition. It was found that the addition of reducing agent to the solution induced depolarization phenomena and decreased or removed the double electric layer capacitance. The chronoamperometry experimental data were analyzed and fitted according to the Scharifker–Hills rule to discover the difference in mechanism between the Ni nucleation and Ni–P nucleation. The morphology of Ni–P and the pure Ni deposits was measured by TEM and SEM demonstrating the ball-like particle shape of Ni–P and flat pure Ni deposits. Based on these experimental results, the nucleation mechanism was illustrated in which the active Ni atoms, produced by electrochemical deposition, act as a catalyst for the reduction of the nickel ions with the reducing agent NaH2PO2 on the cathode surface. The occurrence of the reducing reaction of the nickel ions with NaH2PO2 hindered the in-plane growth of crystalline nickel particles, generating the ball-like particle shape of the deposit. This work provides researchers new insights into the nucleation and growth process of synergetic deposition and offers novel ideas for the fabrication of functional materials by liquid deposition.

Influence of TEOS Content on Anti-corrosion Property of Mercapto Functional Organic Silane Based Sol-gel Coatings on Copper Alloy Surface

Organic-inorganic hybrid sol-gel coatings with high solid content were prepared on cop- per surface by means of hydrolysis-condensation reaction. 3-Mercaptopropyltrimethoxysilane (MP- TMS), tetraethylorthosilicate (TEOS) and hydrochloric acid were used as organic precursor, inor- ganic precursor and catalysts respectively. The chemical composition, and the average size of sol particles and the surface- and cross section-morphology of sol-gel coatings were characterized by