Green Radicals of Potassium Poly(heptazine imide) by Light and Benzylamine
The tinted long-lived ionic carbon nitride radicals were recently introduced and applied in photocatalysis and energy storage. Still the reason for higher activity in the photocatalytic reaction and optimal conditions for generating such radicals remain vague. Herein, we study conditions of carbon nitrides photocharging to achieve higher charge density and validate a convenient method to quantify a number of electrons accumulated in the carbon nitride semiconductors by quenching its radical with methylviologen in dark. In the presence of CO2, potassium poly(heptazine imide) can be charged up to 1000 μmol μmol of electrons per gram of the material using benzylamine as electron donor. Under the same conditions mesoporous graphitic carbon nitride can accumulate only 50 μmol of electrons per gram. The products of benzylamine oxidative coupling are imine and ammonia.