Proceedings of nanoGe Fall Meeting 2021 (NFM21)
Publication date: 23rd September 2021
Ability to photocatalyze different classes of reactions by a single material is desirable to meet the growing challenges in energy research. A diverse pool of catalytic supplies ranging from organic to inorganic to polymeric materials have been explored for harvesting photons and drive various chemical reactions. Among them, semiconductor nanoparticles or quantum dots (QDs) have emerged strongly as efficient photocatalysts due to their high absorption extinction coefficient, electron-hole mobility, size and shape tuneable band gap, photostability and flexible surface chemistry.[1,2] In this direction, we have explored the potency of Indium Phosphide/Zinc Sulfide Quantum Dots (InP/ZnS QDs) to photocatalyze two distinctly different reactions: metal-centred redox and carbon-carbon (C-C) coupling reactions.[3-5] The surface chemistry of the QDs were successfully tuned to stabilize them in polar as well as in non-polar solvents. The QD was effective in photocatalyzing the one electron reduction of ferricyanide to ferrocyanide (in water) in presence of a sacrificial reagent, with high photoconversion yield and recyclability. More striking is the ability of InP/ZnS QD to exclusively photocatalyze a C-C coupling reaction (in organic solvent), between 1-phenyl pyrrolidine (PhPyr) and phenyl-trans-styryl sulfone (PhSO2), without the aid of any co-catalysts or sacrificial reagents (Scheme 1).[5] Good overlap between the action spectra and absorption of QD validates their active participation in these photocatalyzed reactions. Efficient photocatalysis under white-light illumination proves the suitability of InP/ZnS QDs to directly harvest solar radiation as well. Our results project InP/ZnS QDs as a ‘greener’ alternative to toxic metal-ion based QDs for future photocatalytic studies.
The work was supported by DST-SERB India Grant EMR/2015/001561, DST Nano Mission Grant SR/NM/NS-1014/2017, and DST Nano Mission Thematic Unit Programme, India. INC thanks MHRD for Ph.D. fellowship.