About the Speaker:

Professor Ashok K. Ganguli is a Professor of Chemistry at IIT-Delhi (currently on lien) and the Director, Institute of Nano Science and Technology (INST), Mohali. His research interests include designing of nanostructures using microemulsions for applications in photocatalysis, photovoltaics, and electrocatalysis as well as porous functionalised nanostructures for toxin removal and water purification.

About the Seminar:

Title:

Abstract:

An outstanding challenge in the realm of photocatalysis is the development of functional nanomaterials in the visible region of the electromagnetic spectrum. Photocatalytic (PC) and photoelectrochemical water splitting (PEC) is the most promising technique for the direct conversion of solar energy into chemical energy. We have investigated the tunability of electronic and optical properties of semiconductor nanostructures by control of their shape, size¹ and which have applications in water splitting, photocatalysis and dye degradation.² Core-shell, doped and composite heterojunctions have been designed for renewable energy production and environmental remediation under visible spectrum. Coupling of wide band gap semiconductor such as ZnO, NaNbO₃ with narrow band gap semiconductors like Ag₂S, In₂S₃, CuInS₂ etc. (which act as sensitizers) forms efficient heterostructures for the separation of photogenerated charge carriers and makes it a good candidate for visible-light photocatalysis.³ The design of nanostructured materials as photocatalyst or photoelectrodes, and the understanding of their charge-transfer dynamics play a crucial role in achieving high efficiency in photocatalytic and photoelectrochemical water splitting. We have also fabricated double heterojunction nanostructures (with 2D MoS₂ and rGO) for extended stability, suppressing the charge recombination and enhance the life time of photogenerated charge carriers at the interface.^4-6
We have reported^[5] Mn doped BiVO₄ to improve the charge-transport properties of the catalyst. Addition of Mn enables forbidden d-d transitions which is utilized to slow down the charge-carrier recombination and increase efficiency. Cu₂O has been used as a photocatalyst and it holds promise being non-toxic and abundantly available on earth. However, due to lower band edge of Cu₂O, it gets oxidized easily and its high recombination rate of electron-hole pairs which lowers its activity. Tiwari et al. have used MoS₂/rGO as a co-catalyst with Cu₂O to suppress the recombination rate of the photogenerated charge carrier in Cu₂O as well as to inhibit the photocorrosion and provide an electron rich environment to the system.^[7] The ternary composite shows much  higher photoactivity as compared with the bare one. In another report we have designed VS₄-MoS₂-rGO based composite which helps to suppress the charge carrier recombination rate as well as photocorrosion in VS₄ and provides better photoelectrochemical activity and stability of the photo-catalyst.^[8]