# Progress in the Development of Electrodeposited Catalysts for Direct Liquid Fuel Cell Applications
## 6 Summary and Future Challenges  
The US DOE is currently deploying numerous fuel cells for specific uses [125]. Over the last decade, more than 10,000 fuel cell systems have been designed and installed. Several research works have been reported on the effect of catalyst synthesis, characterization (physical, chemical, electrochemical), and catalyst performance on the durability of direct liquid fuel cells. Furthermore, studies on the electrodeposition of Pt, Pd catalysts for fuel cell applications have been carried out at laboratory scale and mostly in three electrode configuration involving half-cell studies. However, data on the real time fuel cell tests employing electrodeposited Pt, Pd-catalysts as anodes, methanol tolerant cathodes in DLFCs are scarce and very limited. Though there are certain key benefits with electrodeposition, one of the major issues is integrating the electrodeposited catalyst architecture as an MEA into the fuel cell, which drastically affects the fuel cell performance and its reliability.  
A systematic integration of the MEAs involving electrodeposited catalyst is suggested to address the reliability challenge. There is still a gap in understanding the long-term durable characteristics of the shape-controlled Pt-based catalysts synthesized by electrodeposition. Investigations on scaling up the electrodeposition process for the synthesis of Pt, Pd catalysts are minimal. Consequently, the technology readiness level (TRL) of the process continues to be at a low level. In contrast, other chemical synthesis processes reach the highest TRL, indicative of a commercially deployable process.  
Therefore, it is essential that a criterion for scaling up the electrodeposition process with good fuel cell tests under real time conditions and life cycle analysis needs to be critically explored in future investigations. There is clearly a lack of data on the durability, electrochemical stability of the electrodeposited Pt and Pd-catalysts both at laboratory scale and real time operating conditions. Having understood the fact that electrochemical corrosion of carbon could primarily influence the performance, the durability of the catalysts, and transition to metal mesh electrodes would be a beneficial approach in the long term. While additive manufacturing techniques are rapidly pacing up, the development of metal mesh-based electrodes followed by electrochemical deposition of Pt and Pd-based catalysts is expected to make a significant impact on the cost reduction while achieving the targets set by the US DOE.  
Few works on the application of DES such as Choline-based ones (Urea/EG) have been tested as suitable alternative electrolyte systems for obtaining shape controlled Pt and Pd electrodeposits ranging from cubes, flowers to octahedrons [111]. While the development of shape-controlled Pt, Pd catalysts from electrochemical deposition processes is gaining attention, the strategy seeks substantial capital investments in order to perform electrochemical depositions at a scale spanning in the range of a few hundred litres of DES. The current market pricing status of ILs and DESs gives a clear indication that increasing their production at a larger scale will offer superior cost competitive benefits to the existing commercial supporting electrolytes, allowing for the possibility of achieving a price of about $1 per kilogram of IL (or) DES [126].  
Many of the works cited in this review focused on Pt, Pd, and their combinations as efficient electrocatalysts which are listed under the EU critical raw materials (CRM). It is also understood that, considering the predominance of critical or semi-critical material components present in DLFCs (such as Ti, for bipolar plates), and their economic relevance for EU markets, a number of scenarios should be devised to achieve acceptable CRM savings [127]. Controlling the Pt, Pd catalyst loading via the single step electrodeposition could meet the EU strategic objectives in achieving the CRM savings by at least 30% and contribute to the cost targets set by the US DOE.