Aromatic ring substituted g-C₃N₄for enhanced photocatalytic hydrogen evolution

Abstract

An all-carbon aromatic ring substitutionally doped g-C3N4was synthesized with greatly enhanced light absorption, band structure and carrier separation, achieving a 3 times higher hydrogen evolution rate (HER).

Promoted Photocatalytic Hydrogen Evolution by Molecular Ring‐Substituting Doping and Regulation of Charge Carrier Migration in Graphitic Carbon Nitride

“…The calculated bands and the total density of states (TDOS), accompanied with projected density of states (PDOS) profiles of C and N elements of CN and CN‐T were exhibited in Figure a,b. The CN showed the property of an indirect gap semiconductor with the E g of 2.58 eV, similar to many previous reports . According to the band decomposed charge‐density distributions at the N 2p states (mainly p x and p y orbitals)‐preponderant valence‐band maximum (VBM, Figure S4a, Supporting Information) and C 2p states (mainly p z orbitals)‐preponderant conduction‐band minimum (CBM, Figure S4b, Supporting Information), the photo‐induced carriers were localized in the vicinity of each other.…”

“…Compared to the previous work in which a benzene‐based co‐monomer with three substituents was employed, the four substituents with much more appropriate positions (1‐hydroxyl and 2,4,6‐chloro) in trichlorophenol provided the preferable sites for the cyclo‐polymerization of tri‐s‐triazine. The hydroxyl substituent group played an important role in the copolymerization.…”

“…According to the band decomposed charge‐density distributions at the N 2p states (mainly p x and p y orbitals)‐preponderant valence‐band maximum (VBM, Figure S4a, Supporting Information) and C 2p states (mainly p z orbitals)‐preponderant conduction‐band minimum (CBM, Figure S4b, Supporting Information), the photo‐induced carriers were localized in the vicinity of each other. It was just the origination of the high recombination tendency in g‐C 3 N 4 . Contrastively, CN‐T exhibited a distinctly smaller E g , as some new bands spread in the protogenetic forbidden band.…”

“…According to the compositions from elemental analysis, a benzene ring‐interposing, and three undoped tri‐s‐triazine units were employed to build the supercell of CN‐T. The lattice parameters of CN‐T had a negligible variation compared to that of CN, indicating the benzene‐based co‐monomer was indeed an ideal molecular‐level doping additive into g‐C 3 N 4 owing to its exact approximation to triazine in shape and size of the ring skeleton . The calculated bands and the total density of states (TDOS), accompanied with projected density of states (PDOS) profiles of C and N elements of CN and CN‐T were exhibited in Figure a,b.…”

Molecular Engineering of Donor–Acceptor Conjugated Polymer/g‐C3N4 Heterostructures for Significantly Enhanced Hydrogen Evolution Under Visible‐Light Irradiation

“…The slurry was then coated onto ITO glass electrodes with an active area of 0.25 cm 2 , and these electrolytes were dried at 120 °C for 1 h to evaporate the solvent in muffle furnace. The photocurrent intensity of as‐prepared electrodes was measured at 0 V versus Ag/AgCl with the light on and off . EIS was determined over the frequency range of 10 2 –10 6 Hz with an ac amplitude of 10 mV at the open circuit voltage under room‐light illumination.…”