Ranjit Thapa
SRM University, Kattankulathur
Ranjit Thapa is an Associate Professor at SRM Research Institute, SRM University. He is also in charge of the Supercomputing Center at SRM University. He is an Associate of Indian Academy of Sciences. He is an active member of Asian Consortium on Computational Materials Science (ACCMS). His research work is primarily focused on first-principles investigation of low-dimensional materials and Pt-less catalysts and exploring the properties of carbon allotrope for energy applications. His main contributions are in bond exchange spillover mechanism, electron doped 2D system as metal-free catalyst, the origin of surface magnetism in graphene, inverse catalyst and π electron-based descriptor. He was selected as an Associate of the Indian Academy of Sciences in 2016.
Session 1D: Inaugural Lectures by Fellows/Associates
Descriptor and indicator for sp2-hybridized carbon-based catalysts
Although pristine graphene has not shown any potential as a catalyst, the presence of dopants and defects triggers its catalytic behaviour. This mystery behind the reactivity of doped defective graphene-based metal-free catalysts is unveiled using density functional theory. The occupancy of pz(π) electrons of C atoms increases near the dopant site due to back-donation mechanism in an N-doped graphene system and decreases in the case of B doping due to donation mechanism. A strong correlation has been identified between the activity of each C site with (i) the pz occupancy (considering occupied sates) and (ii) the value of pz projected density of states at the Fermi level. These parameters are proposed as catalytic descriptors for carbon-based catalysts. In addition, a new and simple catalytic indicator that helps to estimate the ideal sites for oxygen reduction reaction to occur by predicting the optimal values of the adsorption free energies of OH on the various active sites of boron and nitrogen-doped graphene has been identified by the speaker’s group. The origin of catalytic property of graphene-based catalysts, the competition between epoxy and enolate configuration on graphene, the bonding and back-bonding mechanism, the catalytic descriptor and indicator, and the origin of adsorption capabilities of DV-defect will be explained.