Modulating Crystallinity of Graphitic Carbon Nitride for Photocatalytic Oxidation of Alcohols

Abstract

Exploiting efficient photocatalystsw ith strengtheneds tructure for solar-driven alcohol oxidation is of great significance. The photocatalytic performance of graphitic carbon nitrides can be considerably promoted by modulating its crystallinity.R esults confirmedt hat ah igh crystallinity accelerates the separation and transfer of photogenerated charge carriers, thus providing more free charges for photoredox reactions. More importantly, the high crystallinity facilitated the adsorption of benzyl alcohol and desorptiono fb enzaldehydea nd simultaneously lowered the energy barrierf or O 2 activation.A saresult,t he crystalline carbon nitride exhibited aroughlytwelvefold promotion with respectt ot he normalc arbon nitride. The remarkable enhancement of activity can be attributed to the synergistic effects of increased electron-hole separation and increased surface reactionk inetics. These findings will open up new opportunities to modulate the structure of polymers for aw ide variety of organic reactions.

Hydrothermally Induced Oxygen Doping of Graphitic Carbon Nitride with a Highly Ordered Architecture and Enhanced Photocatalytic Activity

“…Zhou et al. recently synthesized g‐C 3 N 4 with modulated crystallinity by post‐treatment involving heating a mixture of g‐C 3 N 4 , KCl, and LiCl . g‐C 3 N 4 with high crystallinity showed strong absorption and greatly enhanced photocatalytic oxidation performance.…”

Crystalline Carbon Nitride Semiconductors for Photocatalytic Water Splitting

“…As revealed by SEM, I-LiK-CN and II-LiK-CN have different morphologies.I -LiK-CN showed spherical particles decorated with small needles, while II-LiK-CN possessed an eedle-like structure (Figure 11 b). [36] TheXRD pattern was different from that of bulk CN and PTI/Li + Cl À ,i ndicating that the as-prepared sample adopted an ew phase (Figure 12 a). Although the surface area of II-LiK-CN is still small (31 m 2 g À1 ), II-LiK-CN exhibited the highest photocatalytic activity among those samples,r eaching 20.3 mmol h À1 .T his is 23 %higher than that of mesoporous CN with asurface area of 208 m 2 g À1 (Figure 11 d).…”

“…[35] Heptazine subunits can also be formed in molten salt environments from traditional precursors.Byusing preheated melamine,W ang and co-workers obtained aheptazine-based CCN by the ionothermal method, which was referred to as g-CN-1. [36] TheXRD pattern was different from that of bulk CN and PTI/Li + Cl À ,i ndicating that the as-prepared sample adopted an ew phase (Figure 12 a). However,t he NMR, FTIR, and UV Raman results,t ogether with XPS analysis, show that the chemical structure of g-CN-1 was similar to that of bulk CN,s uggesting that g-CN-1 was constructed from heptazine subunits.T he light absorption intensity of g-CN-1was significantly higher than that of PTI/Li + Cl À ,and aredshift of the absorption was also observed.…”

Kohlenstoffnitridmaterialien für photochemische Zellen zur Wasserspaltung

“…Wirs tellen uns den Einbau von CN-Photoanoden als Absorber mit breiter Bandlücke zusammen mit einer Photokathode mit kleiner Bandlücke (bestehend aus reichlich vorhandenen Materialien wie etwa Si, [7,98,148] Cu-(In,Ga)Se 2 , [149] CuSbS 2 [150] und Sb 2 Se 3 [151] )f ürd ie gesamte Wasserspaltung vor. [156][157][158][159] Dies kann durch Umkristallisation auf einem Substrat [92] sowie durch das sorgfältige Design des Syntheseverfahrens bei erhçhten Drücken (z. [156][157][158][159] Dies kann durch Umkristallisation auf einem Substrat [92] sowie durch das sorgfältige Design des Syntheseverfahrens bei erhçhten Drücken (z.…”

“…[133] Im Gegensatz zu den gut etablierten Synthesewegen von Kohlenstoffnitridpulvern, Nanostrukturen und deren Hybriden [152,153] sowie der nachgewiesenen Funktionalitäti nv er- [155] eine wichtige Rolle bei der Aktivitätsverbesserung spielen kçnnte (was jüngste Fortschritte bei CN-basierten Pulvern als Photokatalysatoren widerspiegeln). [156][157][158][159] Dies kann durch Umkristallisation auf einem Substrat [92] sowie durch das sorgfältige Design des Syntheseverfahrens bei erhçhten Drücken (z. B. Druckgefäße,v erschweißte Quarzampullen [159] ), Nachbehandlungen bei erhçhter Temperatur,d ie Verwendung von Ionothermalverfahren [156,160] wie etwa eutektische Mischungen geschmolzener Salze oder Kombinationen davon erreicht werden.…”