Polymer electrolyte membrane fuel cells (PEMFCs) continue to receive extensive attention because of their utility as a clean energy source for automotive, stationary, and portable applications.[1] The proton conductivity of the polymer electrolyte membrane (PEM) is one of the key factors limiting the performance of PEMFCs, which depends on the relative humidity, and controls the cost and durability. [2] Consequently, an improvement in the proton conductivity of the electrolyte membrane even by an order of magnitude could change the performance of fuel cells dramatically. [3] Currently, Nafion-based membranes are widely used as the PEM in fuel cells that operate from 60 to 80 8C. Although these membranes show good proton conductivities from 0.1 to 0.01 S cm À1 in a humid environment, they have many limitations, such as: 1) dependence on water for conductivity; 2) high methanol permeability; 3) a tendency to disintegrate in the presence of hydroxyl radicals, an intermediate in the cathode reaction; and 4) moderate mechanical and chemical stability.To improve the performance of electrolytes used in PEMFCs, two different approaches have been adopted. First is the synthesis of alternative membranes that could operate at higher temperatures without the need for humidification. The phosphoric acid doped polybenzimidazole membrane is a widely exploited example in this category. [4,5]

Superhydrophobic multiwalled carbon nanotube bucky paper, fabricated after ozonolysis, shows fascinating electrowetting behavior, which could be remarkably tuned by changing key solution variables like the ionic strength, the nature of the electrolyte, and the pH of the water droplet. More significantly, the droplet behavior can be reversibly switched between superhydrophobic, Cassie-Baxter state to hydrophilic, Wenzel state by the application of an electric field, especially below a threshold value.

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A facile and one-pot method for the synthesis of Pt, Pd, and their alloy nanocrystals along with their exciting electrocatalytic activities toward methanol oxidation have been reported. Unique structures like truncated octahedrons of Pd, Pt, and their alloys like CoPt and PdPt have been synthesized in presence of a reducing solvent like N-methyl pyrrolidone (NMP) and stabilizer like polyvinyl pyrrolidone (PVP). Among these nanocrystals, Pd16Pt84 and Co5Pt95 show tremendous improvement in the electro-oxidation of methanol in acidic media with mass activities of 1790 and 1417 mA/mgPt, respectively (with lower onset potential compared to Pt alone), which is believed to be much higher compared to that of previous reports and state-of-art Pt/C and RuPt/C catalysts, indicating a better alloy formation and stable particle–support interactions.

Single-step preparation of smaller sized (ca. 3 nm, approximate composition Au 923 ATP 241 ) gold nanoparticles (AuNPs) followed by their self-assembly is demonstrated using 4-aminothiophenol (ATP) as a reducing agent in water/N,N-dimethylformamide (DMF). Water and DMF play a crucial role during the reduction process, since nanoparticles are formed neither in water nor in DMF alone at room temperature. Moreover, the morphology of the particles is found to be strongly dependent on the pH of the medium. The instantaneous UV-visible absorption spectrum shows a relatively sharp peak at 550 nm, which becomes a broad band after 1 h of mixing, due to the formation of aggregates. The size of the gold nanoparticles is controlled in the stipulated range by maintaining a critical AuCl 4 -/ATP ratio. Transmission electron microscopic images reveal close-packed assembly of gold nanoparticles induced by the bifunctionality of ATP. Powder X-ray diffraction patterns confirm the metallic face-centered cubic (fcc) lattice structure with ( 111), ( 200), ( 220), and (311) crystal planes. Thermogravimetric analysis shows 22% organic molecules on the surface of AuNPs. The molecular level analysis of the as prepared gold nanoparticles by Fourier transform infrared spectrum shows the presence of -SO stretching. X-ray photoelectron spectroscopic results also confirm the oxidation of -SH during the reduction of AuCl 4ions. The cyclic voltammograms of the monolayer-protected Au nanoparticles show quasi-reversible redox behavior, though the electrochemical features are different from those of the self-assembled monolayer (SAM) of ATP on a gold electrode.

Nitrogen-doped graphene quantum dots (N-GQDs) were decorated on a three-dimensional (3D) MoS 2 –reduced graphene oxide (rGO) framework via a facile hydrothermal method. The distribution of N-GQDs on the 3D MoS 2 –rGO framework was confirmed using X-ray photoelectron spectroscopy, energy dispersive X-ray elemental mapping, and high-resolution transmission electron microscopy techniques. The resultant 3D nanohybrid was successfully demonstrated as an efficient electrocatalyst toward the oxygen reduction reaction (ORR) under alkaline conditions. The chemical interaction between the electroactive N-GQDs and MoS 2 –rGO and the increased surface area and pore size of the N-GQDs/MoS 2 –rGO nanohybrid synergistically improved the ORR onset potential to +0.81 V vs reversible hydrogen electrode (RHE). Moreover, the N-GQDs/MoS 2 –rGO nanohybrid showed better ORR stability for up to 3000 cycles with negligible deviation in the half-wave potential ( E 1/2 ). Most importantly, the N-GQDs/MoS 2 –rGO nanohybrid exhibited a superior methanol tolerance ability even under a high concentration of methanol (3.0 M) in alkaline medium. Hence, the development of a low-cost metal-free graphene quantum dot-based 3D nanohybrid with high methanol tolerance may open up a novel strategy to design selective cathode electrocatalysts for direct methanol fuel cell applications.