"Solar energy is regarded as a promising source for clean and sustainable energy. However, it is not a continuous energy source, thus certain strategies have to be developed to effectively convert and store it. Solar-driven electrocatalytic water splitting, which converts solar energy into chemical energy for storage as fuel hydrogen, can effectively mitigate the intermittence of solar radiation. Water splitting consists of two half reactions: water oxidation and hydrogen evolution. Both reactions rely on highly effective electrocatalysts. This dissertation is an account of four detailed studies on developing highly effective low-cost electrocatalysts for both reactions, and includes a preliminary attempt at system integration to build a functional photoanode for solar-driven water oxidation. For the water oxidation reaction, we have developed an electrochemical method to immobilize a cobalt-based (Co-OXO) water oxidation catalyst on a conductive surface to promote recyclability and reusability without affecting functionality. We have also developed a method to synthesize a manganese-based (MnOx) catalytic film in situ, generating a nanoscale fibrous morphology that provides steady and excellent water oxidation performance. The new method involves two series of cyclic voltammetry (CV) over different potential ranges, followed by calcination to increase crystallinity. The research has the potential to open avenues for synthesizing and optimizing other manganese-based water oxidation catalysts. For the hydrogen evolution reaction, we have developed a new electrodeposition method to synthesize Ni/Ni(OH)2 catalysts in situ on conductive surfaces. The new method involves only two cycles of CV over a single potential range. The resulting catalytic film has a morphology of packed walnut-shaped particles. It has superior catalytic activity and good stability over long periods. We have inestigated [investigated] the feasibility of incorporating manganese-based water oxidation catalysts into TiO2 to build a composite photoanode. Results show that the composite photoanode has good activity under ultraviolet (UV) illumination, and that its catalytic performance can be significantly improved by enabling light collection over a wider range of wavelengths. We have also proposed a scheme for a solar-driven water splitting device that integrates both electrocatalysts with solar energy collection and intensification, and is capable of minimizing mass transfer resistance. The dissertation concludes with suggested future work to further explore the MnOx and Ni/Ni(OH)2 electrocatalysts."--Pages ii-iii.
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