In Situ Bond Modulation of Graphitic Carbon Nitride to Construct p–n Homojunctions for Enhanced Photocatalytic Hydrogen Production

Abstract

Graphitic carbon nitride (g‐C3N4) has recently emerged as an attractive photocatalyst for solar energy conversion. However, the photocatalytic activities of g‐C3N4 remain moderate because of the insufficient solar‐light absorption and the fast electron–hole recombination. Here, defect‐modified g‐C3N4 (DCN) photocatalysts, which are easily prepared under mild conditions and show much extended light absorption with band gaps decreased from 2.75 to 2.00 eV, are reported. More importantly, cyano terminal CN groups, acting as electron acceptors, are introduced into the DCN sheet edge, which endows the DCN with both n‐ and p‐type conductivities, consequently giving rise to the generation of p–n homojunctions. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation, and results in a fivefold enhanced photocatalytic H2 evolution activity. The findings deepen the understanding on the defect‐related issues of g‐C3N4‐based materials. Additionally, the ability to build homojunction structures by the defect‐induced self‐functionalization presents a promising strategy to realize precise band engineering of g‐C3N4 and related polymer semiconductors for more efficient solar energy conversion applications.

g‐C3N4‐Based Heterostructured Photocatalysts

“…Liu et al [198] introduced cyanogroups (CN) as electron acceptors into the bulk ntype gC 3 N 4 structure under mild heating conditions with the addition of NaBH 4 powder. Liu et al [198] introduced cyanogroups (CN) as electron acceptors into the bulk ntype gC 3 N 4 structure under mild heating conditions with the addition of NaBH 4 powder.…”

“…2018, 8, 1701503 Figure 17. [198] Copyright 2016, Wiley-VCH. Inset is the size distribution of the Pt species (bright spots in the STEM image).…”

Synthesis of barbituric acid doped carbon nitride for efficient solar-driven photocatalytic degradation of aniline

“…However, the photocatalytic activity of CN versus the degradation organic pollutants is quite low because of its relatively fast charge recombination and insufficient absorption in the visible-light spectral range. To improve the photocatalytic performance of CN, various modification methods have been applied through structure regulation [10][11][12][13][14][15][16][17][18][19], doping [20][21][22][23][24][25][26][27], surface hetero-junction and copolymerization [28][29][30][31][32][33][34][35][36][37]. Among those methods, copolymerization of CN has been regarded as an efficient route, not only for obtaining an enhance light-absorption, but also for creating surface hetero-structures which could reduce the recombination of photogenerated electron-holes.…”

Ultrathin g-C3N4 Nanosheet-Modified BiOCl Hierarchical Flower-Like Plate Heterostructure with Enhanced Photostability and Photocatalytic Performance

“…Through theoretical calculation, the CB potentials and VB potentials for BiOCl and g-C3N4 are estimated to be about 0.18 eV and 3.48 eV, and −1.08 eV and 1.52 eV, respectively. Under visible-light irradiation, photogenerated electron-hole pairs in g-C3N4 are obtained due to its narrow As is well known, the p-n heterostructure in a photocatalytic system plays a great role in accelerating the efficient separation of photogenerated electron-hole pairs and enhancing the photocatalytic activity [46][47][48][49]. Theoretically, adequate amounts of p-n heterojunctions between (001) facets of BiOCl and (002) facets of g-C 3 N 4 are formed during the synthetic process, which facilitates electrons from the n-type C 3 N 4 in the heterostructure interfaces transferring to the p-type BiOCl.…”