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

Carbon nitride (CN) films have emerged as promising photoelectrodes in photoelectrochemical (PEC) water splitting cells. However, due to its intrinsic poor charge transfer dynamics and the absence of a controllable...Carbon nitride (CN) films have emerged as promising photoelectrodes in photoelectrochemical (PEC) water splitting cells. However, due to its intrinsic poor charge transfer dynamics and the absence of a controllable film deposition method, its performance remains unsatisfactory. Here we report an in-situ textured CN film that strengthened by 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 reversible hydrogen electrode (RHE) without any hole scavengers. We found that the remarkable photocurrent density is originated from synergistic effect of long wavelength photon harvesting and efficient charge migration through experimental characterizations and theoretical verification. The substantial enhancement of PEC activity highlights the importance of nanoengineering revolution in terms of controlling macroscopic film morphology and modulating microscopic electronic structure for precisely designing of multipurpose photoelectrodes.