Photocatalytic overall water splitting using modified SrTiO3

Abstract

Solar light utilization for photocatalytic overall water splitting (POWS) is a promising alternative to electrolysis to produce hydrogen, since photocatalytic water splitting is simple, and can be operated at low-cost. Transformation and storage of solar energy in the form hydrogen can significantly reduce the rate of the greenhouse gas emissions. Given the low-cost and simplicity of photocatalytic hydrogen production, this thesis has focused on designing an efficient photocatalytic water splitting system. SrTiO3 has been shown to be capable of driving photocatalytic overall water splitting under UV light illumination. In this thesis, SrTiO3 is used as the photocatalyst and the performance of SrTiO3 is discussed in the POWS reaction. Several strategies have been applied to understand particular functions of the SrTiO3-based photocatalyst in photocatalytic overall water splitting with following aspects: i) the photocatalytic transients are collected to understand how Ni/NiO co-catalyst is changed during illumination; ii) Mg is doped into the structure of SrTiO3 to improve the photocatalytic activity; iii) Cr2O3 is introduced on Mg:SrTiO3-NiOx composite to improve the stability of photocatalytic gas evolution; iv) state-of-the art semiconductors, Al:SrTiO3 and Mg:SrTiO3, are compared in the same conditions. Generally, the effect of the various modifications on the photocatalytic gas evolution rates has been revealed by reliable on-line GC measurements. Due to the fast detection mode of the GC, the applied setup allows to determine transients in gas-evolution to reveal activity and stability of the tested photocatalysts.