Preparation and Electrochemical Performance of a Graphene Cathode Catalyst Decorated With Pt by Prolysis

For fuel cells, to produce high-quality and low-platinum catalyst is a pressing technical problem. In this study, graphene cathode catalysts with controllable platinum content were decorated by pyrolyzing chloroplatinic acid under various process parameters to obtain a high catalytic activity and durability. The results show that platinum particles generated by pyrolyzing chloroplatinic acid are uniformly loaded on graphene without agglomeration. The average particle size of platinum particles is about 2.12 nm. The oxygen reduction reaction catalytic activity of catalyst samples first increases, then decreases with increasing platinum loading in cyclic voltammetry and LSV. Compared with the commercial Pt/C (20 wt% Pt) catalyst, the initial potential and the current density retention rate of the catalyst decorated with 8% platinum are 55 mV and 23.7% higher, respectively. From i-t curves, it was found that the stability of the catalyst prepared in this paper was improved compared with the commercial Pt/C catalyst. The catalysts prepared in the present research exhibits superior catalytic activity and stability.

The stabilized methane–air counterflow flame into a plus-shaped chamber with platinum catalyst–coated walls: An emission estimation

Analysis of unsteady CH4/Air counterflow premixed flame into a newly designed plus-shaped channel is investigated in this study. The main objective is to explore the impact of platinum catalytic–coated walls of the combustion chamber on the flame characteristics and pollutant emissions. The OpenFOAM platform is used as a numerical simulation tool to investigate the effects of various equivalence ratios, from the range of lean to rich flames, and passing the reaction time on the counterflow flame characteristics and pollutant emissions of a plus-shaped chamber with the platinum catalyst–coated wall. Results show that the integrated temperature over the proposed geometry with platinum surfaces increases by 18% compared to the non-catalytic case. The numerical simulation revealed that presence of the platinum catalyst on the wall of the chamber has significant impact on reducing the pollutant emissions. This is evident as a 99.5% decrease on NO2 emission and a 58% reduction on CO2 formation are found.

Highly Photoactive Titanium Dioxide Supported Platinum Catalyst: Synthesis Using Cleaner Ultrasound Approach

Catalysts increase reaction rates; however, the surface area to volume ratio of catalysts has a vital role in catalytic activity. The noble metals such as platinum (Pt) and gold (Au) are expensive; despite this, they have proven their existence in catalysis, motivating the synthesis of supported metal catalysts. Metal catalysts need to be highly dispersed onto the support. In this investigation, an ultrasound approach has been attempted to synthesise highly photoactive titanium dioxide (TiO2) nanoparticles by the hydrolysis of titanium tetraisopropoxide in an acetone/methanol mixture. To enhance its photocatalytic activity, TiO2 was doped with Pt. The synthesised photocatalyst was characterised by techniques such as particle size analysis (PSA), XRD, FE-SEM, TEM, and EDX. The enhancement in the surface characteristics of Pt-doped TiO2 compared with bare TiO2 support was confirmed with Brunauer–Emmett–Teller (BET) analysis. The enhanced surface area and uniformity in particle size distribution at the nanoscale level were due to the effects of ultrasonic irradiation. The obtained results corroborated the size and composition of the synthesised catalysts. The size of the catalysts is in the nanometre range, and good dispersion of Pt catalysts over the TiO2 support was observed. The UV-Visible spectroscopy analysis was performed to study the optical properties of the synthesised TiO2 and Pt/TiO2 photocatalysts. An increase in the absorbance was noted when Pt was added to TiO2, which is due to the decrease in the band gap energy.

Oxidation of Monoethylene Glycol to Glycolic Acid with Gold-Based Catalyst and Glycolic Acid Isolation by Electrodialysis

In this work, a highly selective and active gold-based catalyst for the oxidation of high concentrated monoethylene glycol (MEG) in aqueous solution (3 M, 20 wt%) is described. High glycolic acid (GA) selectivity was achieved under mild reaction conditions. The optimization of the catalyst composition and of the reaction conditions for the oxidation of MEG in semi-batch mode under alkaline conditions led to a GA yield of >80% with a GA selectivity of about 90% in short reaction time. The bimetallic catalyst 0.1 wt% AuPt (9:1)/CeO2 showed very high activity (>2000 mmolMEG/gmetalmin) in the oxidation of MEG and, contrary to other studies, an extremely high educt to metal mole ratio of >25,000 was used. Additionally, the gold–platinum catalyst showed a high GA selectivity over more than 10 runs. A very efficient and highly selective process for the GA production from MEG under industrial relevant reaction conditions was established. In order to obtain a GA solution with high purity for the subsequent polymerization, the received reaction solution containing sodium glycolate, unreacted MEG and sodium oxalate is purified by a novel down-stream process via electrodialysis. The overall GA yield of the process exceeds 90% as unreacted MEG can be recycled.

Determination of Kinetic Parameters for the Oxygen Reduction Reaction on Platinum in an AEMFC

To promote the development of anion exchange membrane fuel cells (AEMFC), an understanding of the oxygen reduction reaction (ORR) kinetics in porous gas diffusion electrodes is essential. In this work, experimental polarisation curves for electrodes with different platinum catalyst loadings and oxygen partial pressures at the cathode are fitted to a physics-based porous electrode model in the voltage range from open circuit voltage (OCV) to 0.7 V. The model is verified against polarisation curves with different anode platinum catalyst loading, and hydrogen partial pressures. The reactions are described using a two-step Tafel-Volmer pathway at the anode and concentration-dependent Butler-Volmer kinetics at the cathode. The model shows a good fit to the kinetic region with an exchange current density of 1.0e-8 A/cm2, for oxygen humidified to 95 % RH at 50 °C, a charge transfer coefficient of 0.8 and a first order dependence on oxygen partial pressure. For lower oxygen partial pressure, hydrogen crossover is needed for explaining the downward shift of the polarisation curves in the kinetic region. In the experimental data, the polarisation curves show an apparent limitation at lower hydrogen partial pressures, which can be explained by the lower rate of the Tafel step at these conditions.