This dissertation presents surface enhanced photoanodes and oxygen evolution reaction (OER) catalysts for solar water splitting to produce hydrogen. The enhancement could be achieved by either introduced surface plasmon enhanced metallic nanostructures, such as Au or Ag nanoparticles, or adjusted surface structure, chemical composition and band structure of TiO2. This dissertation also presents various electrochemical and spectroscopic techniques used to characterize nanostructured materials for solar water splitting reactions. Firstly, a model photoanode comprised of Ag@Ag2S core-shell nanoparticles (NPs) on a nanostructured TiO2 substrate is presented for visible light sensitive photoelectrochemical properties. The nanostructured electrode is coated with TiO2 nanowires (NW) on Ti plate to provide a high surface area for efficient light absorption and efficient charge collection from Ag@Ag2S NPs. Pronounced photoelectrochemical responses of Ag@Ag2S NPs under visible light responses were obtained. These responses were attributed to collective contributions of local surface plasmon enhancement, enhanced charge collection by Ti@TiO2 NWs, and high surface area of the nanostructured electrode system. The shell thickness and core size of the Ag@Ag2S core-shell structure can be controlled and the optimal photoelectrochemical performance with a core size of 17 nm (in diameter) and shell thickness of 8 nm was formed. Secondly, a Au@CdS/Ti@TiO2 nanostructured photoanode was prepared by decorating a CdS thin film layer onto a Au/Ti@TiO2 NWs substrate. Compared to CdS/Ti@TiO2 NWs photoanode, Au@CdS/Ti@TiO2 exhibits a significant enhancement to water splitting efficiency. iii The enhanced photoelectrochemical catalytic activity is attributed to the surface plasmon enhancement of Au nanoparticles. XPS, XRD, SEM, EDS, high resolution TEM, AC impedance and other electrochemical methods were applied to resolve the structure-function relationship of the nanostructures of Ag@Ag2S/Ti@TiO2 NWs and Au@CdS/Ti@TiO2 NWs electrodes. The studies of the photocatalytic activity of the core-shell structure, as well as a core-shell structure predictive model can further improve the understanding of the interplay between the shell thickness and core size and guide the design of highly efficient core-shell materials. Lastly, chapter 5 of this dissertation presents a high efficiency, durable, and low-cost oxygen evolution reaction (OER) catalyst based on earth-abundant elements, carbon, oxygen, and titanium for renewable energy conversion and storage devices. In this study, we report a highly active nanostructured electrode NanoCOT (C, O and Ti) for an efficient OER in alkaline solution. The NanoCOT electrode is synthesized from the carbon transformation of nanostructured TiO2 in an atmosphere of methane, hydrogen and nitrogen by a CVD process. The NanoCOT exhibits highly enhanced OER catalytic activity in alkaline solution, providing a current density of 1.33 mA/cm2 at an overpotential of 0.42 V, which is about 4 times higher than an IrO2 electrode and 15 times higher than a Pt electrode because of its nanostructured high surface area and favorable OER kinetics. The enhanced OER catalytic activity of NanoCOT is attributed to the presence of a continuous energy band of the titanium oxide electrode with predominantly reduced defect states of Ti (e.g., Ti1+, Ti2+ and Ti3+) formed by chemical reduction with hydrogen and carbon. OER performance of NanoCOT can also be further enhanced by decreasing its overpotential 150 mV at a current density of 1.0 mA/cm2 after coating its surface electrophoretically with 2.0 nm IrOx nanoparticles (NPs).