Tubular g‐C₃N₄ Isotype Heterojunction: Enhanced Visible‐Light Photocatalytic Activity through Cooperative Manipulation of Oriented Electron and Hole Transfer

Abstract

A tubular g-C3 N4 isotype heterojunction (TCNH) photocatalyst was designed for cooperative manipulation of the oriented transfer of photogenerated electrons and holes to pursue high catalytic performance. The adduct of cyanuric acid and melamine (CA·M) is first hydrothermally treated to assemble into hexagonal prism crystals; then the hybrid precursors of urea and CA·M crystals are calcined to form tubular g-C3 N4 isotype heterojunctions. Upon visible-light irradiation, the photogenerated electrons transfer from g-C3 N4 (CA·M) to g-C3 N4 (urea) driven by the conduction band offset of 0.05 eV, while the photogenerated holes transfer from g-C3 N4 (urea) to g-C3 N4 (CA·M) driven by the valence band offset of 0.18 eV, which renders oriented transfer of the charge carriers across the heterojunction interface. Meanwhile, the tubular structure of TCNH is favorable for oriented electron transfer along the longitudinal dimension, which greatly decreases the chance of charge carrier recombination. Consequently, TCNH exhibits a high hydrogen evolution rate of 63 μmol h(-1) (0.04 g, λ > 420 nm), which is nearly five times of the pristine g-C3 N4 and higher than most of the existing g-C3 N4 photocatalysts. This study demonstrates that isotype heterojunction structure and tubular structure can jointly manipulate the oriented transfer of electrons and holes, thus facilitating the visible-light photocatalysis.

Organosilica Nanotube Templates: One‐Pot Synthesis of Carbon‐Modified Polymeric Carbon Nitride Nanorods for Photocatalysis

“…The main absorption at 398.8 eV is assigned to the sp 2 N in the tri‐s‐triazine ring. Absorptions at 400.2 eV and 401.1 eV can be assigned to the bridging nitrogen (C−NH−C) and terminal amino functions (C−NH 2 ), respectively . The C 1s spectrum in Figure c shows two main absorptions with binding energies of 284.6 and 288.0 eV, respectively.…”

“…The presence of oxygen with a content of ≈3.0 wt % might derive from some absorbed oxygen species, such as water, CO 2 , and oxygenated groups, on the surface of the samples. It is common to see O signals with XPS technique on PCN samples . The deconvoluted spectra of N 1s and C 1s, of PCN–BSNT 1/2 –550, PCN–SNT and PCN–Bulk are illustrated in Figures b and Figure c, respectively.…”

Strategies for Efficient Solar Water Splitting Using Carbon Nitride

“…This isotype junction structure was demonstrated to be highly efficient in charge transfer and separation and resulted in a 5‐fold enhanced photocatalytic H 2 evolution activity. In addition, other g‐C 3 N 4 /g‐C 3 N 4 junctions such as tubular g‐C 3 N 4 isotype heterojunction (TCNH), roll‐like g‐C 3 N 4 photocatalyst, and g‐C 3 N 4 /S‐mediated g‐C 3 N 4 (CN/CNS) isotype heterojunctions have also been reported …”

Formation of g‐C3N4 Nanotubes towards Superior Photocatalysis Performance

“…Thus, non‐template methods have to be developed. Melamine or dicyandiamide supramolecular assembly can change the shapes of g‐C 3 N 4 , such as, tube‐like and sphere‐like . But it has a relatively higher scale up to dozens of microns.…”

“…Melamine or dicyandiamide supramolecular assembly can change the shapes of g-C 3 N 4 , such as, tube-like and sphere-like. [18][19][20][21][22][23][24][25] But it has a relatively higher scale up to dozens of microns. Although tube-like g-C 3 N 4 has been obtained by doping (Br [41] and P [27,42] ) in recently, the tube shape is not regular and the diameter is large.…”