Nitrogen Incorporated Photoactive Brownmillerite Ca2Fe2O5 for Energy and Environmental Applications
Durga Sankar Vavilapalli, Soma Banik, Rajagopal Peri, Muthuraaman Bhagavathiachari, M. Muralidhar, M. Murakami, Alicja Klimkowicz, K. Asokan, Ramachandra Rao M. S., Shubra Singh
Abstract
Abstract Ca 2 Fe 2 O 5 (CFO) is a potentially viable material for alternate energy applications. Incorporation of nitrogen in Ca 2 Fe 2 O 5 (CFO-N) lattice modifies the optical and electronic properties to its advantage. Here, the electronic band structures of CFO and CFO-N were probed using Ultraviolet photoelectron spectroscopy (UPS) and UV-Visible spectroscopy. The optical bandgap of CFO reduces from 2.21 eV to 2.07 eV on post N incorporation along with a clear shift in the valence band of CFO indicating the occupation of N 2p levels over O 2p in the valence band. Similar effect is also observed in the bandgap of CFO, which is tailored upto 1.43 eV by N + ion implantation. The theoretical bandgaps of CFO and CFO-N were also determined by using the Density functional theory (DFT) calculations. The photoactivity of these CFO and CFO-N was explored by organic effluent degradation under sunlight. The feasibility of utilizing CFO and CFO-N samples for energy storage applications were also investigated through specific capacitance measurements. The specific capacitance of CFO is found to increase to 224.67 Fg −1 upon N incorporation. CFO-N is thus found to exhibit superior optical, catalytic as well as supercapacitor properties over CFO expanding the scope of brownmillerites in energy and environmental applications.