Papers by Keyword: Methanol Oxidation

Abstract: This study explores the utility of reduced graphene oxide (rGO) as a support material for gold nanoparticles (AuNPs) synthesized via an economically efficient and environmentally friendly electrochemical deposition method conducted at room temperature. Employing a chronoamperometry (CA) method, we successfully synthesize AuNPs in aqueous solutions without additional stabilizing agents. We investigate the influence of substrate and electrodeposition duration on the growth of AuNPs, on indium tin oxide glass substrates and rGO, with electrodeposition durations for comparison. This research highlights the straightforward and rapid one-step synthesis of AuNPs in an aqueous medium and explores the correlation between Au particle size and electrocatalytic performance. We evaluate the electrochemical performance of rGO-supported AuNPs in the context of methanol oxidation reaction (MOR) using cyclic voltammetry in an aqueous medium with an alkaline electrolyte. Notably, AuNPs supported by rGO, featuring an average particle size of 46 nm, exhibit superior electrochemical performance compared to their counterparts with an average particle size of 165 nm when employed as catalysts for the MOR. This superior performance is characterized by a 15 mV more negative oxidation potential (54 mv compared to 39 mV) and over 2.5 times higher oxidation peak current (0.064 mA compared to 0.025 mA), underscoring their efficiency as electrocatalysts for MOR.

Abstract: The multilayer composite films consisting of poly (diallyldimethylammonium chloride) functionalized graphene (PDDA-rGO) and phosphomolybdic acid functionalized graphene (PMo₁₂-rGO) were prepared by layer-by-layer self-assembly method. The {PDDA-rGO/PMo₁₂-rGO}_n multilayer composite films were used as a support for electro-deposition of Pt particles in situ. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy and scanning electron microscopy were employed for examining the composition, structure, and morphology of the catalyst. Results revealed that the Pt/{PDDA-rGO/PMo₁₂-rGO}_n catalyst is successfully prepared and that the multilayer composite films support improves the dispersion of the Pt particles. CV and chronoamperometry were employed to evaluate the electrocatalytic performance for methanol oxidation. Results revealed that the electrocatalytic activity and stability of the Pt/{PDDA-rGO/PMo₁₂-rGO}₃ catalyst for methanol oxidation are considerably improved in comparison with that of the Pt/GCE catalyst. The current density for the oxidation of methanol increased from 0.66 mA/cm² to 1.21 mA/cm². In addition, the ratio of the forward current density to the backward current density (I_f/I_b) was 1.92 for Pt/{PDDA-rGO/PMo₁₂-rGO}₃ catalyst, corresponding to 1.3 times that of the Pt/GCE catalyst. This result indicated that the multilayer composite films remarkably enhanced the electrocatalytic activity regarding methanol oxidation.

Abstract: Orderly TiO₂ nanotube arrays (TNTs) with high surface area became a prospective catalyst support. TNTs were obtained by anodizing Ti plate, and then the Ni-Cu-B/TNTs electrodes were prepared by cyclic voltammetry electrodeposition (CVE) method. SEM, EDS and electrochemical testing were used to investigate the microstructure and catalytic performance Ni-Cu-B/TNTs electrodes for methanol electro-oxidation. Effects of electrodeposition time, CVE scanning rate and times on the methanol electrooxidation were studied. The results show the shape of Ni-Cu-B particles on surface change from fusiform-like to spherical with an increasing of deposition temperature. The peak current density initially increased and then decreased with increasing electrodeposition time, rate and number of CVE scanning. The Ni-Cu-B/ TNTs electrode prepared by 30 cyclic times in 30°C at-0.8~0.2V and the scan rate of 20mV s^-1 appear the best electrocatalytic activity for methanol oxidation. After cycled 1300 times for methanol oxidation, the peak current density decreased by 12%, indicating excellent long term stability of Ni-Cu-B/TNTs electrode.

Abstract: PdCoNi nanocomposites supported on graphene (PdCoNi/G) have been obtained from chemical reduction of metal catalysts and graphite oxide (GO) with a strong reducing agent, followed by calcination at high temperature under N₂ condition, and used for electrooxidation of methanol in direct methanol fuel cell. The morphologies and structural properties of electrocatalysts were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray spectroscopy techniques (X-ray photoelectron spectroscopy XPS) was used to investigate the chemical state of the synthesized catalysts. The results of Pd XPS spectra showed the metallic Pd and PdO phases for precalcined and calcined PdCoNi/G nanocomposite, respectively. The X-ray measurement of Co and Ni displayed the various metallic oxides in synthesized electrocatalysts. For electrochemical analysis, cyclic voltammetry (CV) and chronoamperometry (CA) indicated that the PdCoNi/G nanocomposites enhanced the methanol oxidation, compared to the lower activity in the calcined electrocatalysts.

Abstract: Direct Methanol Fuel Cells (DMFCs) have been postulated as suitable systems for power generation in the fields of portable power sources, remote and micro-distributed energy generation, and auxiliary power units (APU). The main objective of the DURAMET project ((http://www.duramet.eu) is to develop cost-effective components for DMFCs with enhanced activity and stability in order to reduce stack costs and improve performance and durability. The project concerns with the development of DMFC components for application in auxiliary power units and portable systems.

Abstract: In this research, a sequential sol-thermal route has been used to prepare the SnO₂ nanocolloid, Pt nanoparticles were then deposited on the nanosupport to obtain the Pt-SnO₂/MWCNTs. The electrochemical performances of the catalysts were characterized by cyclic voltammetry and chronoamperometry. The Pt (fcc) crystalline was proved to be form on the surface of carbon nanotubes. The Pt based catalyst modified by tin oxides exhibit a electro-chemical performance for methanol electro-oxidation.

Abstract: A facile method to prepare well-dispersed Platinum nanoparticles (Pt NPs) on FTO and TiO₂ nanotube (TNTs) film was reported. The so-prepared Pt/FTO and Pt/TNT film electrodes are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD). The results show Pt NPs have been dispersed on the supporting matrixs uniformly. Electrochemical investigations indicate that Pt/TNT has higher electrocatalytic activity and better tolerance to poisoning species in methanol oxidation than Pt/FTO, which can be ascribed to the high dispersion of Pt NPs on the TiO₂ nanotubes surface. The present method is promising for the design of high performance catalysts for direct methanol fuel cells.

Abstract: Ni coatings were successfully electrodeposited on Ti substrates using galvanostatic technique. The scanning electron micrography showed a smooth coating with a few round particles formed at current density of-1 mA/cm², whereas the Ti surface was fully covered with round particles consisting of like-worm fibrils when applying higher current densities of-5 and-10 mA/cm². The stability and electrocatalytic activity tests were conducted by cyclic voltammetry and potentiostatic techniques. The results indicate that Ni/Ti catalysts prepared at current densities of-5 and-10 mA/cm² possess high active surface area and exhibit higher electrocatalytic activity performance towards methanol oxidation as compared to Ni/Ti prepared at-1 mA/cm². It was concluded that the deposition current density has significantly influenced the formation of Ni coatings on Ti substrate which consequently affecting the performance of electro-oxidation of methanol. The Ni/Ti catalysts also have good stability for the oxidation process in alkaline solution.

Abstract: Reduced graphene oxide (RGO) supported platinum electrocatalyst was successfully synthesized on the glass carbon electrode by the electrodeposition method. Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the Pt/RGO modified electrode towards methanol oxidation. The results revealed that the as-prepared catalyst exhibited high electrocatalytic ability in methanol oxidation, which could be attributed to the excellent properties of the reduced graphene oxide as supporting materials.

Abstract: Pt, Pd and Pt-Pd nanoparticles (NPs) were synthesized on carboxylic graphene (CGR) sheets. The nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR) and UVvis absorption spectroscopy. Their electrocatalytic activity for methanol oxidation was also investigated. The results showed the peak current density of methanol oxidation of Pt NPs-Graphite oxide (GO), Pd NPs-CGR, Pt NPs-CGR and Pt-Pd NPs-CGR is 12.2μA/cm², 14.1μA/cm², 15.1μA/cm² and 21.5μA/cm² respectively. The nanocomposite of CGR as catalyst supports and Pt-Pd NPs as catalyzers is promising for direct methanol fuel cells.