Highly Efficient Oxygen Electrode Obtained by Sequential Deposition of Transition Metal-Platinum Alloys on Graphene Nanoplatelets.

A set of platinum (Pt) and earth-abundant transition metals (M = Ni, Fe, Cu) on graphene nanoplatelets (sqPtM/GNPs) was synthesised via sequential deposition to establish parallels between the synthesis method and the materials' electrochemical properties. sqPtM/GNPs were assessed as bifunctional electrocatalysts for oxygen evolution (OER) and reduction (ORR) reactions for application in unitised regenerative fuel cells and metal-air batteries. sqPtFe/GNPs showed the highest catalytic performance with a low potential difference of ORR half-wave potential and overpotential at 10 mA cm-2 during OER, a crucial parameter for bifunctional electrocatalysts benchmarking. A novel two-stage synthesis strategy led to higher electrocatalytic performance by facilitating the reactants' access to the active sites and reducing the charge-transfer resistance.

Water management improvement in PEM fuel cells via addition of PDMS or APTES polymers to the catalyst layer.

Water management is one of the obstacles in the development and commercialization of proton exchange membrane fuel cells (PEMFCs). Sufficient humidification of the membrane directly affects the PEM fuel cell performance. Therefore, 2 different hydrophobic polymers, polydimethylsiloxane (PDMS) and (3-Aminopropyl) triethoxysilane (APTES), were tested at different percentages (5, 10, and 20 wt.%) in the catalyst layer. The solution was loaded onto the surface of a 25 BC gas diffusion layer (GDL) via the spraying method. The performance of the obtained fuel cells was compared with the performance of the commercial catalyst. Characterizations of each surface, including different amounts of PDMS and APTES, were performed via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses. Molecular bond characterization was examined via Fourier transform infrared spectroscopy (FTIR) analysis and surface hydrophobicity was measured via contact angle measurements. The performance of the fuel cells was evaluated at the PEM fuel cell test station and the 2 hydrophobic polymers were compared. Surfaces containing APTES were found to be more hydrophobic. Fuel cells with PDMS performed better when compared to those with APTES. Fuel cells with 5wt.% APTES with a current density of 321.31 mA/cm 2 and power density of 0.191 W/cm 2 , and 10wt.% PDMS with a current density of 344.52 mA/cm 2 and power density of 0.205 W/cm 2 were the best performing fuel cells at 0.6V.

Preparation of different thin film catalysts by direct current magnetron sputtering for hydrogen generation.

In this study, thin films of Co, Ni, Pd, and Pt were prepared on Co 3 O 4 support material in pellet form using the direct current (DC) magnetron sputtering method for use as catalysts for hydrogen generation from NaBH 4 .Characterization of the catalysts was carried out using X-ray diffraction (XRD), scanning electronic microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). According to cross-sectional SEM images, catalyst thicknesses were observed in the range of approximately 115.3-495.8 nm. The particle sizes were approximately 25.0, 21.4, 33.9, and 9.5 nm for Ni-Co 3 O 4 , Co-Co 3 O 4 , Pd-Co 3 O 4 , and Pt-Co 3 O 4 catalysts, respectively. The increase in NaOH initial concentration provides an increase in the rate of hydrogen generation for Co, Ni, and Pd catalysts. A maximum hydrogen generation rate of 1653 mL/g cat .min was obtained for the Pt-Co 3 O 4 catalyst.