Study of the effect of d-block and p-block dopants on material and photocatalytic properties of srtio3

Photoelectrocatalytic and photocatalytic reactions are gaining momentum as a clean method to generate sustainable fuels such as H2. The Ph.D. study focuses on the identification of suitable d- and p-block dopants and the suitability of doping to enhance the catalytic activity of photochemically stable SrTiO3. In this work, the effect of doping Ga3+, La3+-Ga3+, Cr3+, La3+-Cr3+, and Cs1+-Cr3+ on the properties of SrTiO3 has been extensively studied. Chapter 1 introduces the state-of-the-art research associated with this field and outlines the motivations and aims of the Ph.D. work. Chapter 2 summarizes the synthesis method, and the characterization techniques employed to study the catalysts. Chapter 3 studies a series of high-temperature synthesized Ga3+ doped and La3+ co-doped SrTiO3 samples. Accidental exsolutions and anomalous absorption features were observed in some samples. In addition to extrinsic defects, the role of intrinsic defects such as oxygen vacancies in the photoelectrocatalytic performance was investigated. Chapter 4 studies the Ga3+ doped SrTiO3 synthesized at lower temperatures and how these samples differ in properties from those studied in Chapter 3. This chapter highlights the role of intrinsic material properties like electron affinity and ionization potential and defects such as oxygen vacancies. Chapter 5 investigates the effect of doping SrTiO3 with Cr in its B-site. Cr mono-doping was found to have formed the Cr6+ (d0 configuration) trap states alongside the Cr3+ states. The bulk of this chapter investigates the effect of the Cr3+/Cr6+ ratio on the material properties and their photoelectrocatalytic performances. Chapter 6 details the introduction of an additional N2 annealing step in the standard synthesis route to study its effect on crystallite sizes. Preliminary gas phase photocatalytic CO2 hydrogenation with the standard sol-gel Pechini synthesized samples showed an increasing trend in CO evolution and a new method to quantify photocatalytic data has been reported.