Potassium-Derived Charge Channels in Boron-Doped g-C₃N₄ Nanosheets for Photocatalytic NO Oxidation and Hydrogen Evolution

Abstract

The application of graphitic carbon nitride (g-C3N4) in photocatalytic NO oxidation was limited due to severe recombination of photogenerated carriers and low concentration of oxidizing species. In this work, K and B were introduced into the interlayer and in-plane framework of g-C3N4 to address this challenge through the thermal polymerization process. The synthesized K-doped B-g-C3N4 nanosheets exhibited expanded light absorption and low charge recombination efficiency. In addition, the doping of K and B reduced the band gap of g-C3N4, which corresponded to enhanced light absorption. B was introduced into the in-plane structure by replacing C atoms, which adjusted the in-plane electron distribution. K was inserted into the interlayer by binding to the N and C atoms of adjacent layers. K-derived electron transfer channels were constructed, which increased electron delocalization and expanded the π-conjugate system. More electrons were transferred through the interlayer channels and were involved in the reaction process. The severe carrier recombination and weak transfer were improved due to the synergistic effect of K and B doping. K-doped B-g-C3N4 nanosheets exhibited enhanced generation of superoxide radicals and hydroxyl radicals, which played a key role during NO oxidation. The photocatalytic NO oxidation efficiency of codoped g-C3N4 nanosheets reached 61%, which was 2.1 and 1.2 times of that of pristine g-C3N4 and B-doped g-C3N4, respectively. The codoped g-C3N4 sample still exhibited stable photocatalytic NO oxidation efficiency after five cycles. This result provided a potential idea for improving the charge distribution and transfer of layered materials by codoping metallic and nonmetallic elements and for photocatalytic NO oxidation.

Template-Free Synthesis of Boron-Doped Graphitic Carbon Nitride Porous Nanotubes for Enhanced Photocatalytic Hydrogen Evolution

“…UV–vis DRS was performed to characterize the light absorption ability of the prepared samples; accordingly, the effects of B doping and the cyano group on the light absorption ability of g-C 3 N 4 were studied. As shown in Figure a, after B doping and introduction of the cyano group, the intrinsic absorption capacity caused by π → π* electron transition in heptazine rings increased with the boric acid dosage. , In addition, compared with CNN nanosheets, BCNT porous nanotubes exhibited a progressive red shift. Based on the DRS data, the calculated bandgaps of all samples are presented in Figure b.…”

“…Energy shortage and environmental degradation are two major global problems that can be solved by the development of renewable and clean energy . Hydrogen energy, known as the “ultimate energy source” can be revolutionary owing to its high energy density and nonpolluting nature. − The efficient conversion of solar into hydrogen energy has become a research focus in the field of renewable energy. − Graphitic carbon nitride is a promising photocatalytic material for hydrogen evolution, which has been widely studied in recent years. − Accordingly, a series of modification strategies have been explored to improve its performance, such as crystal structure engineering, − composite structure design, − morphology control, , and defect creation. ,, …”

Electrochemical production of hydrogen peroxide by non-noble metal-doped g-C3N4 under a neutral electrolyte

“…The K-Co/CNNs showed a significant chemical shift of the major C 1s and N 1s peaks compared to the CNNs, which indicated there were strong interactions between the C or N atoms of the tri-s-triazine and K. In addition, the binding energies of K 2p were 295.54 eV (K 2p 1/2 ) and 292.80 eV (K 2p 3/2 ), respectively (Fig. S2C †), 43,44 which indicated that K formed K-C and K-N bonds. According to Fig.…”

Vacancy-Modified Porous g-C3N4 Nanosheets Controlled by Physical Activation for Highly Efficient Visible-Light-Driven Hydrogen Evolution and Organics Degradation

“…5−7 Compared with the traditional TiO 2 photocatalyst, g-C 3 N 4 possesses the ability to utilize visible light, which greatly improves the photocatalytic efficiency. 8 Currently, g-C 3 N 4 is widely used in H 2 evolution, 9 NO removal, 10 O 2 production, 11 H 2 O 2 evolution, 12 and CO 2 reduction. 13 In addition, it can also effectively activate molecular oxygen, which can achieve the photocatalytic conversion of organic groups and the photocatalytic degradation of organic pollutants.…”

“…Thus, the development of new renewable energy as an alternative to petroleum resources becomes imperative. , Recently, photocatalysts have been investigated as environmental friendly materials to transform solar energy into usable energy on the earth. , Graphitic carbon nitride (g-C 3 N 4 ), as a two-dimensional layered metal-free polymer with various excellent characteristics including availability, low cost, nontoxicity, and chemical stability, shows great potential in the field of photocatalysis. − Compared with the traditional TiO 2 photocatalyst, g-C 3 N 4 possesses the ability to utilize visible light, which greatly improves the photocatalytic efficiency . Currently, g-C 3 N 4 is widely used in H 2 evolution, NO removal, O 2 production, H 2 O 2 evolution, and CO 2 reduction . In addition, it can also effectively activate molecular oxygen, which can achieve the photocatalytic conversion of organic groups and the photocatalytic degradation of organic pollutants. , However, owing to the high-speed recombination of photogenerated electron–hole pairs and limited surface area, the practical application of g-C 3 N 4 is dramatically restricted. , …”