# Progress in the Development of Electrodeposited Catalysts for Direct Liquid Fuel Cell Applications
## 2 Progress in the Electrodeposition of Carbon Supported Pt and Pd Catalysts
### Alternative Carbon Supports
Challenges in the development of electrode structure, materials, catalyst, catalyst support, viz., carbon black, carbon nanotubes, carbon nanocoils, carbon nanofibers were discussed briefly. Moreover, some of the developments in novel catalyst support materials, viz., nano structured polypyrrole on carbon, polyaniline on carbon black, were also discussed. For more than a decade, graphene (G) and its oxide have been considered as emerging catalyst supports because of their high surface area, superior electrical conductivity, with improved mechanical strength and elasticity. However, the problem with them is that they tend to irreversible agglomerate and restack to graphite. This affects the surface area and obstructs the dispersion of G-supported Pt (Pt/G) particles in the catalyst ink, which is to be coated on the GDL. Lyophilization could be considered as one of the facile approaches to avoid irreversible aggregation of the graphene oxide (GO). The lyophilization process was introduced to prevent the restacking of these sheets during liquid water evaporation, which is a major problem in the conventional drying process. The advantage of using this approach is that it can avoid the accumulation of Pt/G with more exposure of isolated Pt particles to the electrolytic solutions, which makes them superior in terms of catalytic activity. The development of three-dimensional (3D) graphene architectures is believed to open up a new promising avenue for their application in low temperature DLFCs. Moreover, the monolithic nature of 3D graphene with interconnected pores combined with its high surface area makes it unique as electrode support with high corrosion resistance, superior electrical conductivity for fuel cell applications. [PERSON] et al. [54] examined 3D graphene as electrode support for methanol oxidation for the first time, demonstrated its potential for fuel cell application. Three-dimensional graphene was initially synthesized using nickel foam, ethanol precursors employing chemical vapor deposition (CVD) technique. Pt nanoparticles on 3D graphene were synthesised by pulse electrodeposition, and the performance was compared with the Pt deposited on carbon fibre (CFs), a similar 3D structure support with high chemical stability and electrical conductivity, larger specific surface area, and better three-dimensional network structures [55]. Raman spectroscopy results showed that the 3D graphene possessed single layer and multi-layer domains without any disorders/defects, indicating its high quality. SEM and XRD results showed  
Figure 3: Schematic illustration of electrodeposition of PtRuNi on electrochemically activated MWCNTs and its enhanced catalytic performance towards methanol oxidation reaction [52]. that Pt/3D graphene displayed a well dispersed morphology and smaller particle size in comparison to Pt/CFs. Electrochemical results showed that Pt/3D graphene exhibited higher methanol oxidation catalytic activity and stability. The authors attributed the enhancement in catalytic activity with Pt/3D graphene catalyst to the uniqueness of the 3D graphene in terms of their geometry with monolithic architecture surface with efficient mass transport, electrical conductivity, and dense coating of smaller size Pt nanoparticles. [PERSON] et al. [56] synthesized GO sheets by Hummers method followed by dispersion in distilled water. The resulting suspension was filtered with carbon paper as the filter to separate the GO sheets. Synthesis of Pd clusters was carried out on the GO substrate using pulse electrodeposition technique using a Pd containing solution in HCl medium. SEM images showed the presence of well dispersed Pd on the substrate. They displayed two different morphologies: one is star shaped nano clusters, and the other is cubes, with star shaped nano clusters being more dominant. XRD results in Figure 4 reported by the authors displayed the characteristic peaks, i.e., [111], [200], [220] and [311]), confirming the face centred cubic (fcc) pattern of Pd and its crystalline nature.