Premium
C=C π Bond Modified Graphitic Carbon Nitride Films for Enhanced Photoelectrochemical Cell Performance
Author(s) -
Bian Juncao,
Xi Lifei,
Li Jianfu,
Xiong Ze,
Huang Chao,
Lange Kathrin M.,
Tang Jinyao,
Shalom Menny,
Zhang RuiQin
Publication year - 2017
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201700178
Subject(s) - photocurrent , homo/lumo , x ray photoelectron spectroscopy , materials science , delocalized electron , graphitic carbon nitride , band gap , annealing (glass) , pi bond , electronic structure , photoelectrochemical cell , carbon nitride , photochemistry , crystallography , optoelectronics , chemistry , electrode , bond length , computational chemistry , bond order , chemical engineering , crystal structure , photocatalysis , catalysis , molecule , organic chemistry , electrolyte , engineering , composite material
Applications of graphitic carbon nitride (g‐CN) in photoelectrochemical and optoelectronic devices are still hindered due to the difficulties in synthesis of g‐CN films with tunable chemical, physical and catalytic properties. Herein we present a general method to alter the electronic and photoelectrochemical properties of g‐CN films by annealing. We found that N atoms can be removed from the g‐CN networks after annealing treatment. Assisted by theoretical calculations, we confirm that upon appropriate N removal, the adjacent C atoms will form new C=C π bonds. Detailed calculations demonstrate that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are located at the structure unit with C=C π bonds and the electrons are more delocalized. Valence band X‐ray photoelectron spectroscopy spectra together with optical absorption spectra unveil that the structure changes result in the alteration of the g‐CN energy levels and position of band edges. Our results show that the photocurrent density of the annealed g‐CN film is doubled compared with the pristine one, thanks to the better charge separation and transport within the film induced by the new C=C π bonds. An ultrathin TiO 2 film (2.2 nm) is further deposited on the g‐CN film as stabilizer and the photocurrent density is kept at 0.05 mA cm −2 at 1.23 V versus reversible hydrogen electrode after two‐cycle stability assessment. This work enables the applications of g‐CN films in many electronic and optoelectronic devices.