Metal oxide based magnetic nanoparticles (MNPs) especially Fe3O4, play a crucial role in clinical applications like hyperthermia and drug delivery due to their attractive properties such as superparamagnetism (SPM), biocompatibility and high saturation magnetization. The shape and size distribution of the MNPS, influenced by the synthesis parameters, significantly impact their magnetic interactions. Thus the first part of the thesis, we have performed comprehensive structural and magnetic property analysis of Fe3O4 nanoparticles (NPs) synthesized in different chemical routes to identify a viable synthesis method. However, chemically synthesized MNPs suffer from agglomeration and lack thermal stability, leading to dipolar interactions. To address this, we have employed an in-situ sol-gel technique, tuning magnetic interactions among Fe3O4 NPs by evolving Fe3O4 clusters from the amorphous SiO2 matrix. These composites find applications in magnetic hyperthermia.
The second part focuses on hydrogen (H2) generation via seawater electrolysis, considering its potential as future fuel with high gravimetric density (142 MJ/kg) and zero carbon footprint. Water electrolysis is an effective approach to produce H2 with zero carbon emission. Fresh water consumption in water electrolysis strains limited water resources. An alternative solution is to replace fresh water by seawater; however, seawater electrolysis suffers from multiple issues, such as sluggish kinetics, competitive hypochlorite formation at the anode and corrosion of catalyst and carbon support. To overcome this, this thesis work aims to design cost-effective, corrosion-resistant and durable catalysts for efficient H2 production using seawater electrolysis. Prussian blue analogue (PBA)-based anode, Ni-based cathode and Ni-Fe oxide-based bifunctional catalysts are explored with emphasis on structural analysis and electrochemical performance.
The third part of the thesis is dedicated to the design of iron-oxide-based electrocatalysts for detecting three essential biomarkers in the human body: glucose, cholesterol, and high-density lipoprotein (HDL). Early and simplified detection of these analytes is crucial. Currently, the detection process is tedious and mainly limited to laboratories. Our work discusses the electrochemical detection of these analytes in neutral pH (comparable to human serum, pH 7.4) using iron-oxide-based catalysts, employing both enzymatic and non-enzymatic approaches.