Preparation and Characterization of PtRu Nanoparticles Supported on Nitrogen-Doped Porous Carbon for Electrooxidation of Methanol

N-doped porous carbon nanospheres (PCNs) were prepared by chemical activation of nonporous carbon nanospheres (CNs), which were obtained via carbonization of polypyrrole nanospheres (PNs). The catalysts, PtRu and Pt nanoparticles supported on PCNs and Vulcan XC-72 carbon black, were prepared by ethylene glycol chemical reduction. Transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were employed to characterize samples. It was found that PCNs containing N function groups possess a large number of micropores. Uniform and well-dispersed Pt and PtRu particles with narrow particle size distribution were observed. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that alloy catalyst (Pt1Ru1/PCN) possessed the highest catalytic activity and better CO tolerance than the other PtRu and Pt-only catalysts; PtRu nanoparticles supported on PCN showed a higher catalytic activity and more stable sustained current than on carbon black XC-72. Compared to commercial Alfa Aesar PtRu catalyst, Pt1Ru1/PCN reveals an enhanced and durable catalytic activity in methanol oxidation because of the high dispersion of small PtRu nanoparticles and the presence of N species of support PCNs

Nanofiltration of Aqueous Dye Solution through the Diffused Rough Pores of a Carbonaceous–Kaolinite Amalgamation Membrane

This study demonstrates a supported carbonaceous–kaolinite composite membrane that has a highly porous medium with prevalent submicron pores. These pores exhibit a diffused configuration assembled by carbonaceous (Cn) nodules and kaolin particles wrapped by a thin Cn sheath. The membrane was prepared by three steps: (i) applying an acrylic–kaolin coating to a porous stainless-steel tube; (ii) compressing the dried coated layer in an isopress chamber to ratchet the amalgamated coating layer; and (iii) conducting partial pyrolysis to achieve the Cn-kaolin membrane (CKM), exhibiting a rough and diffused CK amalgam frame inherited from the intense compression. The membrane displays attractive nanofiltration performance, that is, >95% rejection over 30 h and mean permeances of 4–10 L/h·m2·bar for the four probe dyes in water (50 ppm) with different molecular masses and charge types. The intricate and rough pore channels of the membrane agitate tiny turbulences amid the thin permeate streams, which drives an effective solute interaction with the pore walls. Solute retention occurred through entrapment along the pore walls, leading to a boundary layer, which assists further retention via dragging, circulating solute molecules, and transferring them to the retentate. The filtrate permeates through nanopores of the CK amalgam frame

Ion Pair Reinforced Semi-Interpenetrating Polymer Network for Direct Methanol Fuel Cell Applications

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly­(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs

Photoresponsive Liquid Marbles and Dry Water

Stimuli-responsive liquid marbles for controlled release typically rely on organic moieties that require lengthy syntheses. We report herein a facile, one-step synthesis of hydrophobic and oleophobic TiO2 nanoparticles that display photoresponsive wettability. Water liquid marbles stabilized by these photoresponsive TiO2 particles were found to be stable when shielded from ultraviolet (UV) radiation; however, they quickly collapsed after being irradiated with 302 nm UV light. Oil- and organic-solvent-based liquid marbles could also be fabricated using oleophobic TiO2 nanoparticles and show similar UV-induced collapse. Finally, we demonstrated the formation of the micronized form of water liquid marbles, also known as dry water, by homogenization of the TiO2 nanoparticles with water. The TiO2 dry water displayed a similar photoresponse, whereby the micronized liquid marbles collapsed after irradiation and the dry water turned from a free-flowing powder to a paste. Hence, by exploiting the photoresponsive wettability of TiO2, we fabricated liquid marbles and dry water that display photoresponse and studied the conditions required for their collapse

Photoresponsive Liquid Marbles and Dry Water

Stimuli-responsive liquid marbles for controlled release typically rely on organic moieties that require lengthy syntheses. We report herein a facile, one-step synthesis of hydrophobic and oleophobic TiO₂ nanoparticles that display photoresponsive wettability. Water liquid marbles stabilized by these photoresponsive TiO₂ particles were found to be stable when shielded from ultraviolet (UV) radiation; however, they quickly collapsed after being irradiated with 302 nm UV light. Oil- and organic-solvent-based liquid marbles could also be fabricated using oleophobic TiO₂ nanoparticles and show similar UV-induced collapse. Finally, we demonstrated the formation of the micronized form of water liquid marbles, also known as dry water, by homogenization of the TiO₂ nanoparticles with water. The TiO₂ dry water displayed a similar photoresponse, whereby the micronized liquid marbles collapsed after irradiation and the dry water turned from a free-flowing powder to a paste. Hence, by exploiting the photoresponsive wettability of TiO₂, we fabricated liquid marbles and dry water that display photoresponse and studied the conditions required for their collapse