Interfacial engineering of two-dimensional g-C3N4/graphene oxide heterojunctions from ball milling for photocatalytic reaction promotion

Abstract

Spatial charge transfer kinetics are the main obstacles limiting the performance of solar-driven hydrogen production. However, the potential design of low-cost two-dimensional (2D) heterojunctions to enable efficient photocatalytic water splitting remains critical for practical applications. To address these issues, this study proposes a one-pot glucose-assisted ball milling process to construct 2D metal-free heterojunctions, combined p-type O-bonded graphene oxide (GO) with n-type intercalated graphitic carbon nitride (CN). The novel sugar-assisted ball milling strategy not only accelerates the exfoliation of CN into monolayer nanosheets but also catalyzes the reduction of GO to its reduced form, resulting in a significant enhancement of electrical conductivity and charge carrier mobility within the composite matrix. The resultant photocatalysts with optimal proportion (i.e., glucose = 0.75 g) not only align the energy levels to provide a channel for efficient interlayer charge separation but also effectively promote a hydrogen generation rate of 89.2 μmol h⁻¹ g⁻¹ for outperforming CN and CN/Pt by factors of 13.5 and 2 as well as improved stability. Mechanistic insights from Kelvin probe force microscopy confirm the unique contribution of the built-in electric field from van der Waals heterojunctions to interfacial charge transport. By monitoring charge transfer dynamics in transient absorption spectra, the prolonged lifetimes of photo-generated electrons signify their favorable role in the photocatalytic process. This study provides valuable interfacial engineering strategies in scalable synthesis of superior photocatalysts, paving the way for the future development of advanced functional materials for sustainable energy solutions and environmental remediation.