Synthesis and efficient visible light photocatalytic H2 evolution of a metal-free g-C3N4/graphene quantum dots hybrid photocatalyst

Abstract

In this work, we report a systematic study of the relationship between photocatalytic properties of hydrogen evolution and structures and morphologies of g-C 3 N 4 prepared by different precursors (urea, melamine and dicyandiamide). The photocatalytic performances of H 2 production are affected by the method and degree of polymerization, the degree of protonation, and the morphology of g-C 3 N 4 prepared

Improvement of g-C3N4 photocatalytic properties using the Hummers method

“…For the C1 s spectra, both at samples show the same peaks located at 284.6 eV and 288.0 eV. The peak at 284.6 eV is typically attributed to the sp 2 CAN or graphitic carbon [23]. The peak at 288.0 eV is indexed to N@CAN 2 of the striazine ring (C 3 N 3 ) units or heptazine (C 6 N 7 ) unit.…”

“…The absorption peak at 1632 cm À1 correspond to the stretching vibration modes of the CAN heterocycles [21]. A broad band near 3000-3400 cm À1 corresponds to the NAH and OAH stretches, associated with amino groups (ANH 2 or @NH groups) and surface absorbed H 2 O molecules [22,23]. Fig.…”

“…Fig. 5B shows the photocurrent density-time curves of the bulk g-C 3 N 4 and E-g-C 3 N 4 to investigate the transmission ability of the photogenerated carriers under visible light irradiation [23,28]. The results show that the E-g-C 3 N 4 exhibits a higher photocurrent response than the bulk g-C 3 N 4.…”

“…The bandgap increases from 2.72 eV for the bulk g-C 3 N 4 to 2.85 eV for the E-g-C 3 N 4 after the Hummers treatment. The larger bandgap, which shows a stronger oxidation-reduction ability, can quickly cause the charge-transfer rate [23] and quantum confinement effects, which result in a high removal efficiency [24,25].…”

Graphene Quantum‐Dot‐Modified Hexagonal Tubular Carbon Nitride for Visible‐Light Photocatalytic Hydrogen Evolution

“…[15,16] Meanwhile, GQDs have variouss urfacef unctional groups andt ypical fluorescence properties. [19] The former methodi st he way to obtain smallsize quantum dots from bulk graphene materials by chemical, physical, and electrochemical methods. [19] The former methodi st he way to obtain smallsize quantum dots from bulk graphene materials by chemical, physical, and electrochemical methods.…”