Development of Nickel Cobalt Sulfide within an Organic Microrod Array: An Efficient Catalyst for Oxygen Evolution Reaction

Das, Soumik (2019) Development of Nickel Cobalt Sulfide within an Organic Microrod Array: An Efficient Catalyst for Oxygen Evolution Reaction. Masters thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Electrochemical splitting of water into hydrogen and oxygen is being considered as one of the most promising technologies for energy storage. Recently, transition metal (TM) based materials have demonstrated high catalytic efficiency toward oxygen evolution reaction and their electrocatalytic activity can be further enhanced by integration with other conductive materials. This motivated us to develop a room-temperature fabrication of encapsulated TM-based nanocatalysts for highly efficient and durable water oxidation. Our group have experimentally figured out the advantages of transition metal sulfides over their oxide counterparts for promoting oxygen evolution reaction as an electrocatalyst in the recent past. Using that concept, we prepared nickel cobalt sulfide nanoparticles embedded in Cu-TCNQ microrods (Sulfurized NiCo₂@Cu-TCNQ) on a copper mesh substrate as the catalyst in this work. After the electrocatalytic activity, the TM-sulfide was then converted into corresponding hydroxides/oxyhydroxides that in turn acts as the active sites for electrocatalysis. The ratio of Ni and Co was varied to figure out the optimum ratio and after the sulfurization NiCo₂@Cu-TCNQ was found to show best electrocatalytic performance in terms of both overpotential requirement (245 mV for 10mA/cm²) and stability under alkaline conditions. The step by step structural changes and morphological changes have been probed here by doing control studies. The studies suggest a transformation of sulfurized NiCo₂@Cu-TCNQ into corresponding carboxylate after the sulfurization, which in turns is helping in the enhanced OER activity.

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