Research Projects

Solar-to-chemical energy conversion (photocatalysis) is a sustainable method for preparing value-added chemicals. Photocatalysts can access redox potentials corresponding to the energy associated with the solar spectrum, but their energetics are limited by their band gap and light excitation energy. About 93% of the solar spectrum is composed of visible and NIR light, which means photocatalysts can absorb a maximum energy of 3.1 eV (400 nm) and access the corresponding redox level. However, many reactions have higher reduction potentials than this maximum attainable redox level, forcing scientists to use UV light for photochemical reactions. The proposed proposal aims to access higher redox levels in photocatalysts using visible or NIR light. The choice of photocatalysts will be semiconductor nanoparticles or quantum dots (QDs) due to their excellent photostability and size-dependent optical and redox properties. The use of triplet-triplet annihilation (TTA) process in photocatalysis will ensure access to redox states unimaginable in QD photocatalysts using visible-light. Electrochemically modifying QD photocatalysts will also allow access to energy levels above the band gap. Electrochemical replenishment of the valance band of a continuously irradiated photocatalyst will ensure population-inversion in the conduction band, populating energy levels above the conduction band minima. The hypothesis will be tested in standard reactions catalyzed under UV light with wide-band photocatalysts. Success will ensure the replacement of UV light with visible/NIR light in photocatalysis. The idea of 'photocatalysis beyond the bandgap' will enhance product yield and selectivity of complicated reactions like CO2, N2, and NO3- reductions.