Polyvinyl alcohol-modified graphene oxide as a support for bimetallic Pt–Pd electrocatalysts to enhance the efficiency of formic acid oxidation

The aim of this research was to study the efficiency of polyvinyl alcohol (PVA)-modified graphene oxide (GO) as a supporting material for catalysts that oxidize formic acid. The active metal catalysts (e.g., Pt and Pd) were electrodeposited on PVA/GO surfaces. The morphologies of the prepared catalysts were characterized by scanning electron microscopy and transmission electron microscopy, while their chemical compositions were identified by X-ray diffraction and X-ray photoelectron spectroscopy. The results show that compared with the other catalysts on GO, the prepared active PtPd alloy catalyst nanoparticles with 11.49–20.73 nm sizes were well dispersed on the PVA/GO surfaces. Electrochemical results indicate that the activities of the catalysts with PVA provided a higher current density than that of the catalysts without PVA. The bimetallic 3Pt3Pd/PVA/GO catalyst showed the greatest catalytic activity, stability, and CO oxidation when compared to those of other catalysts. The electronic, morphological, and structural properties promote the mass-charge transfer through the interaction. These results indicate that the PVA-modified GO provides a suitable site for active bimetallic catalyst surfaces, resulting in excellent formic acid oxidation and high CO elimination. The 3Pt3Pd/PVA/GO electrocatalyst is promising for enhancing formic acid oxidation.     

Glycosylated foldamers to probe the carbohydrate-carbohydrate interaction

The synthesis of a triglycosylated helical foldamer based on a combination of cyclopentyl- and pyrrolidinyl-based amino acids is described. This structure is stable in water, maintaining as it does a series of carbohydrate units in proximity to one another, and represents the basis of a new approach to the study of carbohydrate-carbohydrate interactions.     

Successive electrodeposition of polydopamine and PtPd metal on a graphene oxide support for use as anode fuel cell catalysts

Successive electropolymerization of dopamine and electrodeposition of Pd and/or Pt on a graphene oxide (GO) support were used to prepare anode catalysts for low-temperature fuel cells. Transmission electron microscopy images were used to investigate the morphologies and distribution of the prepared catalysts, which showed the metal formed as nanoparticles on the catalysts. The GO surface was favorable for the modification with electropolymerized polydopamine (PDA) and the electrodeposition of metal catalyst nanoparticles using a simple preparation process. The PDA-loaded GO composite was used as a matrix for the dispersion of Pt and Pd nanoparticles. GO could be simultaneously modified by PDA and reduced without using reducing agents. The electrocatalytic performance of the catalysts for the oxidation of selected small molecule fuels (e.g., methanol, ethanol and formic acid) was examined. An outstanding catalytic activity and stability was found for the prepared Pt/Pd/PDA/GO composite, which was attributed to the high active surface area.     

Catalytic investigation of PtPd and titanium oxide-loaded reduced graphene oxide for enhanced formic acid electrooxidation

Preparation, characterization, and electrocatalytic study of the electrodeposited Pt and Pd (e.g., Pt and PtPd) catalysts on titanium dioxide (TiO₂) modified reduced graphene oxide (rGO) support for formic acid oxidation were performed. The catalyst composites are labeled as xPt/rGO-TiO₂, xPtyPd/rGO-TiO₂, and yPd/rGO-TiO₂ where x and y are cycle numbers of metal electrodeposition (x and y?=?2–6). The characterizations of the catalysts were performed by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Small and dispersed metal nanoparticles are obtained on rGO-TiO₂. The catalytic performances for formic acid oxidation were measured by cyclic voltammetry (CV) and chronoamperometry (CA). The electrocatalytic results reveal that the bimetallic 4Pt2Pd/rGO-TiO₂ catalyst facilitates formic acid oxidations at the lowest potentials and generates the highest oxidation currents and also improves the highest CO oxidation compared to the monometallic 6Pt/rGO-TiO₂ catalyst. According to the experimental data, the Pd and TiO₂ enhance the electrocatalytic activity of the catalysts towards the formic acid oxidation; the improved catalytic performance of the prepared catalysts strongly relates to the high electrochemically active surface area (ECSA) investigated.

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Graphical abstract TEM image of xPtyPd/rGO-TiO₂ and its CV towards oxidation