Crystalline oxygen-bridged carbon nitride from self-assembled supramolecular intermediate for efficient photocatalytic H2 evolution

Abstract

Crystalline carbon nitride can potentially manifest heightened light-harvesting efficiency, coupled with proficient charge migration rates, attributable to the diminished count of recombination centers for photoexcited carriers. This phenomenon stems from the extensive π-conjugated framework and the dispersion of π-electrons. This investigation adopts a self-assembly strategy, utilizing hydrogen-bonded bridging melem with cyanuric acid, to yield crystalline oxygen-bridged carbon nitride. The strategic introduction of oxygen doping, positioned at the junction between heptazine units, and the crystalline architecture endow BCN with augmented photocatalytic H₂ evolution capacity. This culminates in a H₂ production rate under visible light irradiation that surpasses that of pristine BCN by approximately 23.2 times, and an apparent quantum efficiency (AQE) of 13.2% at 420 nm. The confluence of the oxygen-bridging mechanism and crystalline architecture within carbon nitride profoundly augments the partition and migration pace of photoexcited carriers, resulting in the amplified photocatalytic performance of BCN. This strategic paradigm charts a fresh trajectory toward an exponential augmentation of carbon nitride performance, nimbly regulating both crystalline architecture and elemental doping.