Amine Functionalized Cs₃Sb₂I₉ Nanocrystals for Photocatalytic Reduction of CO₂

Panda, Satyaprakash (2022) Amine Functionalized Cs₃Sb₂I₉ Nanocrystals for Photocatalytic Reduction of CO₂. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Satyaprakash Panda (17MS044)) 17MS044_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Photocatalytic CO2 reduction reaction (CRR) has recently gained attention because of the increasing global warming. Lead-free halide perovskites are an alternative class of semiconductors used extensively in photocatalysis because of their high charge motility, better stability, and less toxicity to the environment. A binary ligand system of an organic aliphatic acid and an organic aliphatic amine is generally employed to synthesize perovskite nanocrystals. However, the exact role of each ligand and the mechanism involved in forming the lead-free perovskite NCs are not clear. We have used the P-3m1 phase of the Cs₃Sb₂I₉ perovskites because of its high charge mobility, lesser effective charge carrier mass, direct bandgap, and high charge mobility. In this work, for the first time, we synthesized the Cs₃Sb₂I₉We have demonstrated that amine is not necessarily needed to synthesize pure phase material. However, amine plays a significant role in controlling a defined morphology, improving the stability by surface passivation, and thus decreasing the surface defects. Cs₃Sb₂I₉ NCs were also synthesized by varying the alkyl chain NCs colloidally without the help of amine. length of the amine to find their role in determining the morphology. We have used the Cs₃Sb₂I₉ NCs in a solvent/electrolyte system to perform photocatalytic CO₂ reduction reaction. Our system CSI_DA achieved a photocatalytic CO yield of 73.4 μmol/g and a CH₄ yield of 15.6 μmol/g, around three folds more than what was reported earlier for Cs₃Sb₂I₉ systems. Tho total electron consumption rate is ~296 μmol/g with an overall selectivity towards CO2 reduction to be 92%. We have demonstrated that shorter alkyl chain ligand gives better activity because of their less insulating environment, which matches their high current density.

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