ENGINEERING HALIDE PEROVSKITES FOR SOLAR FUEL PRODUCTION BY CO2 PHOTOCATALYTIC REDUCTION

CO2 levels have been on the rise for the last few decades. As moves towards renewable energy have increased, so have new ways to avoid low-energy density batteries with poor long-term storage capability. Prime amongst those ways, solar fuels produced photocatalytically from CO2 have recently become a much-discussed topic of research. From many photocatalytic materials proposed, lead halide perovskites show the most promise, due to their excellent optoelectronic properties. Their bandgap thermodynamically allows for both oxidation of water and CO2 reduction. This is, however, counterbalanced by low stability and still relatively high charge recombination. In this doctoral work, new ways of stabilising the material and improving performance will be found. An extensive literature review analyses the nature of instability and methods to extend the lifetime of halide perovskites, with a focus on those applicable to photocatalysis. This is followed by an accounting of the means to improve performance, often through heterojunctions or addition of metal electrocatalysts. A reporting of the characterisation and figures of merit relevant to photocatalysis is given in this work, with its accompanying significance. Early stage results on the effect of halide tuning on CsPbX3 showed a linear band gap shift between Cl and I. The instability of CsPbI3 and derivatives motivated the shift in focus to the analysis of CsPbBr3, CsPbCl3, and mixed Cl/Br perovskites.
Current state-of-the-art lead halide perovskite photocatalysts use a 2D charge transport material and a metal cocatalyst. However, no study has focused in-depth on the specific interactions between different halide perovskites and these additives, especially on their effect on selectivity. This study will deliver a systematic approach to decipher any specific interactions between halide doping, addition of reduced graphene oxide, and addition of Ag in order to create atmosphere-stable halide perovskite photocatalysts. This serves as new development for gas-phase CO2 photoreduction.