Hydrogen is an attractive energy carrier and is part of an idealistic future wherein it serves as a clean energy source. In the presence of... Show moreHydrogen is an attractive energy carrier and is part of an idealistic future wherein it serves as a clean energy source. In the presence of oxygen, it can be converted to water in fuel cells with the release of heat and electrical work. Electrolysis of water is an important route to hydrogen generation. Alkaline water electrolysis is preferred over electrolysis in acidic medium due to the possibility of lowering stack costs and enhancing the library of stable electrocatalyst materials available for the electrochemical reactions. The high anode overpotential arising from the sluggish oxygen evolution reaction (OER) has led to significant interest in developing stable and active OER electrocatalysts. IrO2 (state of the art catalyst), RuO2 and PGM-based pyrochlores are suitable catalyst materials that exist today, but there is benefit in finding cost-effective alternatives. In this study, the pyrochlore oxides containing non- Platinum Group Metals (non-PGM) metals were synthesized by solid state reaction and were tested for their OER activity but none of the materials tested, exhibited OER activity and a comparison was attempted between the pyrochlores containing PGM metals as against those containing non-PGM metals. Additionally, perovskite oxides of the form La[Ni(1-x-y)CoxFey]O3 (where 0≤x≤1 and 0≤y≤1) were synthesized by the co-precipitation method. Many of these perovskites exhibited electron conductivities greater than 0.1S/cm, eliminating the need to add carbon for OER studies and implying the likelihood of making conducting electrodes with these materials without the additives like carbon. The perovskites LaNi0.6Co0.4O3 or LaNi0.6Fe0.4O3 with x/y =0.4 had conductivities of the order of 10S/cm. The electrocatalytic activity for the OER was studied using a rotating disk electrode (RDE) in 0.1M KOH and catalyst loading of ~100μg/cm2. The perovskite LaNi0.5Co0.5O3 (x=0.5, y=0) had the onset potential of ~1.50V against RHE, and all these perovskites had onset potentials ~0.1-0.15V higher than the benchmark IrO2 that has an onset potential of ~1.43V. Few of the perovskites were also evaluated for their oxygen reduction activity (ORR) implying that these materials can be used as bi-functional catalysts. M.S. in Chemical Engineering, July 2016 Show less
