Rotating Disk Slurry Au Electrodeposition at Unsupported Carbon Vulcan XC-72 and Ce3+ Impregnation for Ethanol Oxidation in Alkaline Media

Abstract

A robust electrodeposition method consisting of the Rotating Disk Slurry Electrode (RoDSE) technique to obtain Au nanoparticles highly dispersed on a conductive carbonaceous support, i.e. Vulcan XC-72R, for ethanol electrooxidation reaction in alkaline media was developed. Ceria was used as a co-catalyst using a Ce(III)-EDTA impregnation method in order to enhance the catalytic activity and improve the catalyst's overall stability. The RoDSE method used to obtain highly dispersed Au nanoparticles does not require the use of a reducing agent or stabilizing agent and the noble-metal loading was controlled by the addition and tuning of the metal precursor concentration.Inductively coupled plasma and thermogravimetric analysis indicated that the Au loading in the catalyst was 9%.Particle size and characteristic Au fcc crystal facets were determined by X-ray diffraction. The morphology of the catalyst was also investigated using electron microscopy techniques. In addition, X-ray absorption spectroscopy was used to corroborate the presence and identify the oxidation state of Ce in the system and to observe if there are any electronic interactions within the 8% Au/CeOx/C system. Cyclic voltammetry of electrodeposited 9% Au/C and Ce promoted 8% Au/C showed a higher catalytic current density for ethanol oxidation when compared with commercially available catalysts (20% Au/C) of a higher precious metal loading. In addition, we report a higher stability towards the ethanol electrooxidation process, which was corroborated by 1 mV/s linear sweep voltammetry and chronoamperometric studies.

Manufacture of Pd/Carbon Vulcan XC-72R Nanoflakes Catalysts for Ethanol Oxidation Reaction in Alkaline Media by RoDSE Method

“…10,11 The rotating disk slurry electrodeposition technique (RoDSE), developed in our laboratory, has been proven to deposit metal nanoparticles on different support materials for bulk production of catalyst powder. [12][13][14][15][16][17][18] This technique works by maintaining a circular flux of solution by rotation of the working electrode, constantly replenishing the concentration of the support material and metal ion in the diffusion layer (Figure 1), allowing the electrodeposition of the metal to take place in the conductive support. To the best of our knowledge, the RoDSE is the only electrochemical synthesis technique where you are able to produce a hybrid material in powder form.…”

Silver–Palladium Electrodeposition on Unsupported Vulcan XC-72R for Oxygen Reduction Reaction in Alkaline Media

“…Then, 50 mg of Vulcan in 1.0 M H 2 SO 4 was placed under ultrasound for 4 h prior to the RoDSE experiment. This increases the nucleation sites on the surface of the carbon particles and creates a well dispersed slurry . For Ag, a reductive potential of 0.4 V vs RHE was applied after every addition of 1 mL of a solution of 5 mM AgNO 3 metal salt precursor with a period of 20 min for a total of 4 h of electrodeposition time at 2000 rpm.…”

“…With this technique, the electrodeposition occurs because the metal NPs are electrochemically reduced by two main pathways: (1) when the metal ions under study and the surface of the glassy carbon working electrode come into contact and (2) when the carbon support is charged enough, by the glassy carbon working electrode, to reduce the metal ion to a metallic state when it comes in contact with surface of the RDE mentioned before. 21 This technology is very useful, because it has several advantages: monitoring the size and distribution of the NP, avoiding their agglomeration, and controlling and varying the loading of metal particles that are added to the slurry to produce a hybrid material in powder form, 21 The RoDSE technique has been studied for the electrodeposition of metal NPs using different kinds of support such as Vulcan XC-72R, 24 carbon nano-onions, 25 single wall carbon nanotubes, 25 graphene oxide, 26 and zeolites. 27 To our knowledge, the RoDSE technique has not been used to electrodeposit the combination of Ag and another precious metal on a carbon support as described in this work.…”

“…This increases the nucleation sites on the surface of the carbon particles and creates a well dispersed slurry. 24 For Ag, a reductive potential of 0.4 V vs RHE was applied after every addition of 1 mL of a solution of 5 mM AgNO 3 metal salt precursor with a period of 20 min for a total of 4 h of electrodeposition time at 2000 rpm. Afterward, the slurry was filtered and rinsed with nanopure water (18.2 MΩ•cm EDM Milli-Q Direct 16).…”

Combined Rotating Disk Slurry Electrodeposition–Spontaneous Galvanic Displacement for Pt-M (M = Co, Ni, and Cu) Catalyst Synthesis for the Oxygen Reduction Reaction in Alkaline Media

“…Different synthesis methods, such as hydrothermal, sol–gel, and chemical reduction methods, could be used to obtain ORR electrocatalysts. Electrodeposition is another alternative where the rotating disk slurry electrodeposition (RoDSE) methodology has been studied for over 10 years for catalyst preparation on unsupported carbon materials, for example, Vulcan XC-72R (CBV), single wall carbon nanotubes, reduced graphene oxide, and carbon nano-onions. − Some of the benefits of this method are the fact that no heat treatment is required and scale-up synthesis can be obtained, providing a fluent transition from the rotating disk electrode (RDE) to the membrane electrode assembly (MEA). RoDSE has been successfully used to synthesize Pt, Pd, , Au, Ag, , and Fe nanoparticles supported on different carbon supports for energy conversion applications.…”