Steering the interlayer energy barrier and charge flow via bioriented transportation channels in g-C3N4 : enhanced photocatalysis and reaction mechanism

Abstract

Even though graphitic carbon nitride (g-C3N4, CN for short) is ideal for photocatalysis, the inherent defects of a high interlayer energy barrier and low charge separation efficiency have limited the transportation and transformation of carriers. Here, we tackle these challenges to craft interlayer bioriented electron transportation channels via intercalation of K+ and NO3− species between the neighboring layers of CN, lowering the interlayer energy barrier and driving the interlayer charge flow. A combined theoretical and experimental method is proposed to demonstrate the construction of interlayer bioriented channels in CN. The energy barrier of electron transfer between adjacent layers observably decreases from −34.16 eV of CN to −28.17 eV of KNO3 co-doped CN (CN-KN for short). The charge flows induced by the two channels could transfer toward opposite directions, resulting in a significantly boosted separation and transportation efficiency of carriers. Consequently, abundant electrons can be provided to activate the O2 molecule and dramatically facilitate the production of reactive species to participate in the photocatalytic redox reaction. The reduced energy barrier, promoted charge separation and transportation, and enhanced O2 activation endow CN-KN with superior visible light photocatalytic performance in NO purification. The conversion pathways of photocatalytic NO oxidation on CN and CN-KN have been elucidated and compared based on the ESR spectra and in situ DRIFTS spectra. A new absorption band at 2150 cm−1 associated with NO+ intermediate is discovered for CN-KN. This research highlights the crucial issues in steering the interlayer energy barrier and charge flow via bioriented transportation channels to promote the separation, transportation, and transformation efficiency of photogenerated carriers and paves a new way to effectively elevate the photocatalytic performance of layered photocatalysts.