Facilitating carrier separation of hierarchical carbon nitride by a nucleation processable strategy in photocatalytic H2 evolution

Abstract

The adjustment of hierarchical micro-nanostructure and morphology has been identified as an effective strategy to optimize photocatalytic performance of carbon nitrides (CNs). Nevertheless, environmental and additive-free construction of CNs with hierarchical structures is still challenging. Herein, a nucleation processable strategy is proposed to construct hierarchical CNs with unique morphologies (planar, donuts-like, flower-like), free of harmful additions. In this strategy, nucleation process and crystal growth degree of supramolecular precursors (cyanuric acid-melamine aggregates) can be controlled via tuning the initial supersaturation in the crystallization. Moreover, the formation mechanism of unique morphologies is illustrated in this article, based on the understanding of nucleation and crystal growth. Among the as-prepared CNs, owing to its hierarchical architecture and unique morphology, the flower-like CN0.25 display the optimal charge separation and excellent photocatalytic hydrogen evolution performance of 1880 μmol h−1 g−1, which is 27 times higher than that of the bulk CN. Additionally, the apparent quantum yield of CN0.25 is achieved 6.7% at 420 nm. The experimental results demonstrate that the nucleation processable strategy developed herein may provide a new pathway in the design of hierarchically structured CNs with desirable photocatalytic performance.