Abstract
Photoelectrochemical (PEC) water splitting is one of the most promising renewable energy technique, which directly converts solar energy into storable and clean fuel, hydrogen. However, the solar-hydrogen efficiency (SHE) of PEC cell remains limited (< 1%) because of the insufficient photovoltaic and photocurrent generation of photoanodes. A clear understanding the hole quasi Fermi level (EFp) profile in the band gap is important to predict the photovoltaic and photocurrent. In this work, the solution growth metal oxide nanowires (NWs) were prepared as photoanodes for PEC investigation. My research is focused on (i) calculating hole concentration of photoanodes (TiO2 and α-Fe2O3), (ii) establishing a series of band diagrams to summarize the photocurrent generation at various bias potential, and (iii) reducing the hole transport and transfer resistance by post annealing Ti doped α-Fe2O3 for enhanced PEC performance. In addition to the energy production, the development of energy storage is also important. Supercapacitors (SCs) are one of promising energy storage technique. It can be fully charged and discharged in seconds; as a consequence, it can provide the instant power for electric vehicles. The limit of SCs is the high cost. Thus, a low cost and high power density of SCs is greatly required. MnO2 is a potential candidate of SCs because of its low cost and high theoretical specific capacitance (1370 F g-1). However, the poor electrical conductivity limits its capacitive performance. In this work, the high surface area and high conductive RuO2 NRs were used as substrate to improve the charge transport of MnO2. High specific capacitance of 793 F g-1 was achieved at a scan rate of 2 mV s-1 in 1 M Na2SO4 aqueous solution.