In situ textured carbon nitride photoanodes with enhanced photoelectrochemical activity by band-gap state modulation

Abstract

Carbon nitride (CN) films have emerged as promising photoelectrodes in photoelectrochemical (PEC) water-splitting cells. However, due to their intrinsic poor charge transfer dynamics and the absence of a controllable film deposition method, their performance remains unsatisfactory. Here, we report an in situ textured CN film that is strengthened by a band-gap state modulation strategy with superior PEC performance. The optimized film possesses a 15-fold improvement in photocurrent density over pristine CN film, reaching up to 119.2 μA cm⁻² at 1.23 V versus RHE without any hole scavengers. Through experimental characterizations and theoretical verifications, we found that the remarkable photocurrent density originates from the synergistic effect of long wavelength photon harvesting and efficient charge migration. The substantial enhancement of PEC activity highlights the importance of nanoengineering in terms of controlling the macroscopic film morphology and modulating the microscopic electronic structure for the precise design of multipurpose photoelectrodes.