Crystalline Carbon Nitride Semiconductors for Photocatalytic Water Splitting

Abstract

Conjugated carbon nitride (CN) is an emerging and promising semiconductor photocatalyst for water photolysis owing to its unique properties. However, the traditional thermally induced polymerization of N‐containing precursors typically produces melon‐based CN solids with amorphous or semi‐crystalline structures with only moderate photocatalytic performance. Many strategies have been developed to prepare crystalline CNs (CCNs), such as high‐temperature and high‐pressure routes, ionothermal synthesis, and microwave‐assisted synthesis. In this Minireview, we summarize the progress that has been made in the synthesis of CCNs and their application in photocatalytic water splitting reactions. Three kinds of CCNs are mainly discussed according to their polymeric subunits. Challenges associated with CCNs and their future development are also included.

Intramolecular Charge Transfer and Extended Conjugate Effects in Donor–π–Acceptor‐Type Mesoporous Carbon Nitride for Photocatalytic Hydrogen Evolution

“…Graphitic carbon nitride (g-C 3 N 4 )i sa n attractivem etal-free photocatalyst for H 2 production. [1][2][3][4][5][6][7][8] However,i nt he intrinsic conjugatede lectronic system consisting of multiple tri-s-triazine units, the charges eparation is uncontrolled as there is no physical force to guide the migration of electrons. The excited electrons could migrate randomly from the bulk to surface reactive sites throught he adjacentt ri-s-triazine units.…”

Achieving Efficient Incorporation of π‐Electrons into Graphitic Carbon Nitride for Markedly Improved Hydrogen Generation

“…In recent years,a sm etal-free,h ighly active and stable photocatalyst, g-C 3 N 4 has garnered much attention for H 2 production upon exposure to visible light. [3][4][5][6] Pristine g-C 3 N 4 has a2 .7 eV band gap,a bsorbing only light below 460 nm. [7] To this end, to sufficiently utilize visible light, various strategies such as heterojunction, porosity,a nd heteroatom doping have been invoked to expand the light absorption range of g-C 3 N 4 .…”

Noble Metal-Free TiO2-Coated Carbon Nitride Layers for Enhanced Visible Light-Driven Photocatalysis

“…Photocatalytic technology, a promising strategy for addressing energy shortages and environmental pollution, is important for the production of hydrogen via water splitting and the degradation of organic pollutants [1][2][3][4]. TiO 2 , discovered by Fujishima in 1972 [5], is the most widely studied and applied semiconductor photocatalyst and is non-toxic, stable, and cheap [6][7][8].…”