Synthesis, characterization and photocatalytic performance of p-type carbon nitride

Abstract

p-Type organic semiconductors are attractive to develop new photo-and photoelectro-catalytic systems, particularly if the conduction band is located at negative redox potentials. An easy synthetic route to produce carbon-doped carbon nitride (C n>3 N 4) with a stable p-type semiconducting character was optimized. The precursors used were melamine and triaminopyrimidine. The p-type C >3 N 4 exhibited a remarkable photoactivity under visible light compared with pristine C 3 N 4 , which is a stable n-type organic semiconductor deeply studied as heterogeneous photocatalyst for many environmental applications. The photoelectrochemical features of the synthesized p-type materials and pristine C 3 N 4 were deeply investigated with chronopotentiometry and cyclic voltammetry, in the dark and under different illumination conditions, and then compared with the photocatalytic activity using 2fluorophenol as substrate and different radiation sources. The p-doping with carbon of C 3 N 4 reduces the band gap, slightly moves the potential of the valence band, and increases the conduction band to more positive potentials, thus precluding the application of these materials when large negative redox potentials are needed.

Unravelling the Mechanisms that Drive the Performance of Photocatalytic Hydrogen Production

“…The p-n heterojunction is similar to the type II heterojunction. However, the formation of a built-in electric field improves and speeds up charge separation, as reported by Etacheri et al [7], Wang et al [28], Yang et al [30], and Capilli et al [63]. Nevertheless, it is very difficult to obtain experimental evidence supporting the difference between both mechanisms.…”

“…For instance, both TiO 2 and SiC have a band gap of 3.2 eV with a corresponding absorption wavelength of 380 nm in the UV spectrum (Figure 1). On the other hand, graphitic carbon nitride (g-C 3 N 4 ) has a band gap of 2.7 eV (Figure 1), which partially absorbs visible light [63]. Enhanced photocatalytic activity in the visible range is consistent proof of the interaction between the semiconductors.…”

Controllable Synthesis of Phosphorus‐Doped Graphitic Carbon Nitride via a Simple Phosphorus Compound Towards Enhanced Visible‐Light Photocatalytic Performance

“…[23][24][25][26] Different phosphorus sources may exert different effects on the structure of CN and further result in variation of photocatalytic performance with the change of phosphorus precursors. Many different phosphorus compounds were used to synthesize phosphorus-doped g-C 3 N 4 (PCN), such as hexachlorotriphosphazene, [21,27,28] aminoethylphosphonic acid, [26] melamine phosphate [29,30] imidazoliumhexafluorophosphate, [31,32] phytic acid, [33] nitrilotris (methylene)-triphosphonic acid, [34] (hydroxyethylidene)diphosphonic acid, [35] triphenylphosphine, [36] (NH 4 ) 2 HPO 4 , [37] NaH 2 PO 2 , [38] NaH 2 PO 2 ⋅H 2 O, [39] NH 4 PF 6 , [40] sodium pyrophosphate. [41] However, these phosphorus precursors may cause some uncontrollable factors that would lead to inaccurate experimental results in the preparation, such as the introduction of non-phosphorus elements into CN and the impact of released gases on the structure of CN, and also give rise to the environmental pollution in the thermal polymerization.…”

Core/Shell Structure of Mesoporous Carbon Spheres and g-C3N4 for Acid Red 18 Decolorization

“…Recently, graphitic carbon nitride (g-C 3 N 4 , GCN) has received huge scientific interest due to its many advantages, including easy preparation, non-toxicity, high chemical and thermal stability, and moderate band gap leading to good visible-light response [1][2][3][4][5]. Thus, GCN is considered as a promising multifunctional catalyst for many processes such as photocatalytic decomposition of organic and inorganic pollutants, photocatalytic H 2 and O 2 evolution, CO 2 reduction and other energy conversion processes [4,6].…”

“…O 2 − radicals(2,3). The holes in VB of GCN are not able to react with OHto yield •OH due to lower potential than +1.99 eV (E0(OH -/•OH) = +1.99 eV/vs.…”