Carbon based Metal Oxide Nanostructures for Solar Generation of Hydrogen

Abstract

Rapid depletion of traditional non renewable energy sources have led to the search of an alternative clean future fuel i.e. Hydrogen . Photoelectrochemical (PEC) H2 production, using solar energy to split water, is a promising method for production of hydrogen as it utilizes solar radiation and water, both of which are freely available. newlineThe search of an ideal semiconductor is a crucial issue for efficient production of hydrogen via PEC water splitting. Hematite (and#945;-Fe2O3) and titanium di oxide (TiO2) photoelectrodes have been selected as materials of interest for the present thesis. However, certain limitations of these metal oxides like poor charge transport kinetics and recombination of photogenerated carriers hamper the utilization of these electrodes for a PEC cell in its present state. Thus, this thesis has been aimed at modification of nanostructured and#945;-Fe2O3 and TiO2 by using highly conducting CNT (Carbon Nanotube)/graphene nanostructures, in order to overcome their limitations in the direction of getting an efficient PEC system. newlineVarious combinations of CNT/GNP (graphene nanoplates) based and#945;-Fe2O3 and TiO2 systems in layered as well as in composite form (at different ration) were synthesized by sol-gel spin coating method and investigated for their PEC response. Various structural, chemical, electrical and optical characterizations were also carried out to analyze the PEC data. newlineOutcome of the present thesis is as follows. All the prepared CNT and GNP modified and#945;-Fe2O3 and TiO2 composite and bilayered thin films exhibited prominent photocurrent density as compared to their unmodified counterparts. However, composite films proved to be more promising as compared to bilayered photoelectrodes. MWCNT has been identified as best conducting scaffold, among three different conducting scaffolds, MWCNT/SWCNT/GNP, within the limit of study for both the and#945;-Fe2O3 and TiO2 composite systems. Optimum amount of CNT and GNP in and#945;-Fe2O3 and TiO2 have shown the best PEC response due to better charge transfer kinetics and combated the recombination of the charge carriers. newline newline