Our group is at the forefront of developing new electrocatalytic materials for a variety of applications. These range from low and medium temperature fuel cells (PEM and Phosphoric acid imbibed membrane systems), electrolyzers (oxygen, chlorine and hydrogen), electrochemical pumps, enzyme base biofuel cells and sensors and reactors for tailored conversion of bio-fuels. In all of these our efforts involve developing tailored systems designed from ground up using chemical intuition and our unique capabilities in elucidating structure property relationships via careful electrochemical measurements and in situ spectroscopy, especially those using synchrotron based x-ray scattering and absorption.
In the recent past we have made seminal contribution to the state of the art Pt and Pt alloy electrocatalysts for both oxygen reduction as well as improving kinetics at the anode electrode covering a wide range of fuels, these encompass reformate tolerance, direct methanol and ethanol oxidation. These efforts have now merged with efforts to improve performance of Pt alloys for oxygen reduction in phosphoric acid electrolytes as well as in the case of newly emerging alkaline electrolyte membranes. Our range of new materials include, non noble metal inorganic materials such as chalcogenides, metal organic frameworks and those using polymer metal complexes. The range of efforts underway include the following:
(A) Conventional area of the current state of the art fuel cells (low and medium temperature) encompassing those based on H2/Air, Reformate/Air as well as direct alcohol oxidation based systems. The current state of the art catalysts in the area of low and medium temperature acid based systems which includes proton exchange membrane fuel cells based H2 & reformate/Air and low temperature direct alcohol oxidation based technology (i.e. direct methanol fuel cells) as well as medium temperature phosphoric acid imbibed membrane based systems, are entirely based on various Pt and Pt alloy systems both supported and unsupported. However all the economics for making these systems mainstream such as the combined heat and power distributed systems or back-up power modules have to eventually transition to either ultra low noble metal loading or progress towards non noble metal based catalysts. Our primary goal in this arena is to (a) prepare tailor made conventional Pt and Pt alloy electrocatalysts based on specifics of the applications. (b) Produce ultra-low Pt based direct deposited electrodes based on previously developed ion beam assisted deposition techniques. This has demonstrated mass producible ultra-low Pt based electrodes. (c) In the elevated temperature arena pertaining to phosphoric acid imbibed membranes novel electrocatalysts based on Pt alloys have been developed with superior performance and more importantly stability as compared to Pt/C. Portfolio of IP has been developed by LEAP and filed as invention disclosure at NEU. Non Pt based electrocatalysts have been recently demonstrated with comparable performance to Pt alloys albeit with 10-15% lower performance at typical operating cell potential such as 0.65 V. Such comparable performance is a result of immunity to poisoning as a result of anions, primarily di-hydrogen phosphate (H2PO4-). Superior stability is also reported. Such comparable performance has also been demonstrated with ceramic based electrolytes such as the CsH2PO4, which possess the same anion, however at a further elevation in temperature (250-300°C). This technology has been recently filed by LEAP as a provisional patent.
(B) In the arena of biofuels conversion LEAP has filed new invention disclosures in 2009. These refer to (i) clean up processes for bio-diesel production, (ii) selective cleavage of unsaturation in long chain methyl esters (bio-diesel analogs) and (iii) removal of oxygenated moieties using electrochemical reduction. These series of electrochemical reactors are aimed at strategic production of aviation grade fuels from bio-fuels providing a lower energy consuming route as compared to conventional refinery based technology. The latter is often accused of consuming more energy than delivering at the end stage.
(C) LEAP has developed and filed an IP filed for novel Pt alloy electrocatalysts which have demonstrated significant improvement of reformate tolerance as compared to conventional PtRu electrocatalysts. These electrocatalysts have demonstrated ability to tolerate ten fold higher CO content in inlet feed streams. Originally developed as reformate tolerant fuel cells, these electrocatalysts are ideal for H2 pump where CO content of several percent can be fed to anodic stream with these electrocatalysts in the presence of high levels of CO¬2. Corresponding cathode being titania supported Ru-oxides.
(D) New in-house technology based on titania supported Ru and Ir oxide with tailored dopants have been developed for both hydrogen and oxygen evolution. This will be specifically tailored for membrane processes to replace conventional electrolyzers which use semi-membrane electrode configurations. These assemblies are expected to lower noble metal loading and significantly lower the overpotential losses in these processes.
(E) Hybrid electrodes in the context of flow through batteries represent an opportunity for overcoming some of the steep challenges in the current state of the art flow through battery technology mainly pertaining to rate capability. We have successfully demonstrated electrocatalysts capable of operating in the difficult halide containing environment. These electrocatalysts are under development at LEAP and have been tested with promising preliminary data.