Executive Summary :
Objective: The main objective of the proposed research is to reduce the overpotential of carbon alloy catalyst towards ORR in acidic environment compared to Pt/C. Designing a new catalyst in which Pt metal atom doping (metal content is < 1%) in to the matrix of carbon alloy using a simple chemical route is an effective strategy to reduce such overpotential without losing the performance of carbon alloy catalyst. In this case, a proper selection of efficient carbon alloy which shows better ORR reduction current and electrochemical stability is crucial. Doping precious metal atoms on such carbon alloy reduces the overpotential for the ORR in acidic environment. The objectives of the proposed research is given below:
1. An electrocatalyst with ultra-low Pt loading (<1 wt.%) by doping Pt atoms on surface carbon alloy to achieve a better oxygen reduction reaction comparable with 20-40 wt.% Pt supported on carbon. This method reduces the cost of catalyst dramatically without changing its overall performance.
2. Identifying the nature of bonding between single metal atom and carbon and the catalytic center with advanced characterization tool
3. Detailed ORR mechanism on single Pt atom doped electrocatalysts
4. Validation of Pt single atom doped carbon catalyst in polymer electrolyte fuel cell (H2-O2 and DMFC) with area of 4-25 cm2.
Summary: This proposal propose the development of oxygen reduction reaction (ORR) electrocatalyst by doping Pt metal atom on carbon alloy (carbon containing hetero atom and low cost metal centre like Fe) derived from conducting polymer for proton exchange membrane fuel cells (PEMFCs). Using such doping strategy, it is possible to overcome the currently existing barrier between Pt-free system and Pt based catalyst for ORR in PEMFC cathode without affecting the catalyst cost. Such precious metal atom doped carbon alloy improves the device performance and durability. Apart from the Pt supported catalyst (eg. Pt/C), doping of metal atoms improves the active reaction centres by utilizing the metal centre almost 100%. In acidic environment, the existing Pt-free, Fe-Nx doped systems, show an overpotential of 100 mV compared to Pt/C catalysts for ORR. By doping less than 1% of Pt on such non-Pt carbon alloy catalyst, not only reduces the overpotential but also improves over all mass and specific activity of the electrocatalyst. More importantly, the cost of the catalyst can also be reduced compared to currently using commercially available Pt/C. Currently existing strategy such as atom layer deposition (ALD) of precious metal is not a viable strategy for bulk synthesis of the catalysts. So the main focus of the proposal is the preparation of electrocatalystthrough a simple viable chemical routes. Apart from the catalyst synthesis, a detailed material characterization is planned to identify the nature of bonding such metal atoms with carbon, detailed mechanism for the ORR on such metal centres, influence of carbon support etc. planned in the proposal. Moreover, validation of prepared electrocatalyst in fuel cell of low active area is also a major focus of the proposal. The precious metal doping strategy has wide scope in the energy sector where the low cost materials experiences much overpotential to meet the activity of current state-of-the-art catalysts.