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 - Funding Information:
We gratefully thank Prof. Hsisheng Teng from National Cheng Kung University, Taiwan for providing access to the H2 production measurements. The authors are thankful for the financial support of Ministry of Science and Technology, Taiwan under grant No. MOST-108-2119-M-259-002.
Funding Information:
We gratefully thank Prof. Hsisheng Teng from National Cheng Kung University, Taiwan for providing access to the H 2 production measurements. The authors are thankful for the financial support of Ministry of Science and Technology, Taiwan under grant No. MOST-108-2119-M-259-002 .
Publisher Copyright:
© 2020
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
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
VL - 273
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
SN - 0926-3373
M1 - 119036
ER -