TY - JOUR
T1 - Dual roles of [NCN]2- on anatase TiO2
T2 - A fully occupied molecular gap state for direct charge injection into the conduction band and an interfacial mediator for the covalent formation of heterostructured g-C3N4/a-TiO2 nanocomposite
AU - Nimbalkar, Dipak B.
AU - Ramacharyulu, P. V.R.K.
AU - Sahoo, Smruti R.
AU - Chen, Jun Ru
AU - Chang, Chun Ming
AU - Maity, Amarendra N.
AU - Ke, Shyue Chu
N1 - Publisher Copyright:
© 2020
PY - 2020/9/15
Y1 - 2020/9/15
N2 - When low density of melamine is calcined with a-TiO2 at 550 °C, two FT-IR peaks observed at 2048 and 2066 cm−1 are assigned to NCN2- covalently attached to a five-coordinated Ti atom and an oxygen vacancy, respectively, complemented by DFT computation. Admixture of NCN2- HOMO(π2p, 87.5 %) with the high energy Ti(3d, 12.5 %) destabilizes and upshifts the NCN2- HOMO into the a-TiO2 bandgap. A five-line EPR pattern derived from 71 % of atomic spin density localized on two equivalent 14N nuclei, observed under sub-bandgap excitation, verifies the presence of a molecular gap-state. The NCN2--a-TiO2 exhibits excellent H2 production at a rate of 5101 μmol.h-1.g-1. Upon increasing melamine concentration, the rapid and simultaneous decreases of NCN2- FT-IR and NCN1- EPR signals accompanied by transitions of other spectroscopic data to those characteristic of tri-s-triazine demonstrate that the formation of heterostructured g-C3N4/a-TiO2 proceeds via the intermediacy of NCN2--a-TiO2, thereby a mechanism is proposed.
AB - When low density of melamine is calcined with a-TiO2 at 550 °C, two FT-IR peaks observed at 2048 and 2066 cm−1 are assigned to NCN2- covalently attached to a five-coordinated Ti atom and an oxygen vacancy, respectively, complemented by DFT computation. Admixture of NCN2- HOMO(π2p, 87.5 %) with the high energy Ti(3d, 12.5 %) destabilizes and upshifts the NCN2- HOMO into the a-TiO2 bandgap. A five-line EPR pattern derived from 71 % of atomic spin density localized on two equivalent 14N nuclei, observed under sub-bandgap excitation, verifies the presence of a molecular gap-state. The NCN2--a-TiO2 exhibits excellent H2 production at a rate of 5101 μmol.h-1.g-1. Upon increasing melamine concentration, the rapid and simultaneous decreases of NCN2- FT-IR and NCN1- EPR signals accompanied by transitions of other spectroscopic data to those characteristic of tri-s-triazine demonstrate that the formation of heterostructured g-C3N4/a-TiO2 proceeds via the intermediacy of NCN2--a-TiO2, thereby a mechanism is proposed.
UR - http://www.scopus.com/inward/record.url?scp=85084370313&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85084370313&partnerID=8YFLogxK
U2 - 10.1016/j.apcatb.2020.119036
DO - 10.1016/j.apcatb.2020.119036
M3 - Article
AN - SCOPUS:85084370313
SN - 0926-3373
VL - 273
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
M1 - 119036
ER -