Executive Summary : | The most important concern for humanity during the last few decades is the production of clean energy for sustainable development. Fuel cell is a highly efficient and zero-emission electrochemical energy conversion device that directly transforms the stored chemical energy into electrical energy. Direct methanol fuel cell (DMFC) is an important type, mainly useful for stationary applications at low operation temperature and easy to operate due to no requirement of humidification in comparison to its counterpart. Polymer electrolyte membrane (PEM) plays central importance in governing the performance and durability of DMFC. The commercialization of DMFC is mainly hampered due to its higher cost and significant methanol permeability through polymer electrolyte membrane which results in the reduction of performance. Presently, Nafion® is extensively used as PEM and due to its very high cost, it majorly contributes towards the total cost of DMFC compared to other components. Moreover, a significant reduction in performance due to high methanol crossover is another drawback of Nafion®. Therefore, the development of efficient and cost-effective PEM as an alternative solution of Nafion® is obvious for DMFC commercialization. So, the development of next-generation nano-composite membranes using functionalized nanoadditive and low cost, high chemical, mechanical, and thermally stable sulfonated polyether ether ketone (sPEEK) as a base polymer matrix is proposed in this project. To obtain much-enhanced performance and long-term durability for the PEM, advanced nanomaterials such as graphene nanoplatelets, graphene quantum dots, hydroxyapatite ([Ca₅(OH)(PO₄)₃]x, ˂ 200 nm), need to be incorporated as an additive to synthesize nanocomposite membranes. Further, to develop next-generation advanced nanocomposite membranes, the compatibility issue (i.e. phase separation) of additives (nanomaterials) with base polymer matrix is a concern that needs to be tackled carefully. So, to overcome the above mentioned polymer-compatibility issue, appropriate structural modification, as well as suitable chemical functionalization, needs to be carried out to result in modified engineered nanomaterials as additive to develop next-generation nanocomposite membranes. Thus appropriate structural modification and chemical functionalization of the nanomaterial as an additive would establish itself as a key step since it will manipulate the ionic nano-channel size for enhanced proton conductivity and also lead to restriction of methanol permeability with the fine-tuning of the microporous channels. Thus the developed additives will be especially useful to obtain improved proton conductivity along with restriction of methanol crossover which is a significant concern for DMFCs. Combinedly, all three routes will result in the development of next-generation nanocomposite membranes for DMFC, and other applications such as H₂-O₂ fuel cell and water electrolyzers. |