The high efficiency and energy density of miniaturized fuel cells provide an attractive alternative to batteries in the portable power generation market for consumer and military electronic devices [1]. The best fuel cell efficiency is typically achieved with hydrogen, but safety and reliability issues remain with current storage options. A variety of alternative hydrogen carriers are being investigated. Catalytic decomposition of chemical hydrides such as sodium borohydride, sodium hydride, lithium hydride and sodium aluminum hydride has been reported [cf. 2, 3]. Another possibility is reforming of hydrocarbon based fuels. The typical volumetric and gravimetric densities for hydrocarbon fuels such as methanol and diesel are higher than chemical hydrides. Hence on-board reforming of hydrocarbon fuels for portable power generation is as an attractive proposition.
The focus of my postdoctoral work is on developing tools for designing and realizing autothermal hydrogen generation using variety of hydrocarbon based fuels such as methanol. We have designed and fabricated a silicon based reactor consisting of a reformer –burner unit. The burner ensures complete combustion of residual gases to maintain operating temperature. The reformer is integrated with a palladium membrane for subsequent hydrogen purification. Since microreactors possess high surface area to volume ratio, thermal management is a key issue. To address this problem, reactor design principles are employed to minimize the heat losses. In my doctoral thesis I explored synthesis of advanced nanomaterials including perovskites using aqueous combustion synthesis (CS) for fuel cell catalysts. Aqueous CS is a novel route to prepare advanced materials including perovskites, ferrites and zirconia. One version of this process involves a self-sustained reaction between metal nitrate solutions and fuels (e.g. glycine, hydrazine, etc). Specifically, after preheating to moderate temperature (~115 -150 C), the reaction medium, in the form of a viscous liquid, self-ignites. Further, owing to high exothermicity of the system, combustion temperature rapidly reaches ~1200 C and converts the precursor materials to non-agglomerated fine crystalline powders of the desired complex oxide within short time (~ few seconds). By studying the effect of numerous parameters such as fuel: nitrate, ambient atmosphere, system dilution we could propose the reaction mechanism for the process. Fundamental knowledge of the mechanistic details helped us in obtaining powders with tailored properties.
My post-doctoral research has exposed me to a variety of microfabrication techniques including bulk micromachining and photolithography. During my doctoral work, I gained expertise in analytical techniques such as XRD, FESEM, BET surface area analyzer, FTIR, Elemental analyzer, UV-Vis spectrophotometer, voltammetry, mass spectrometry, TGA/DTA, EDX analysis and gas chromatography.