Engineering in-plane π-conjugated structures in ultrathin g-C3N4 nanosheets for enhanced photocatalytic reduction performance

Abstract

In this study, an energetic materials (EM) deflagration process coupled with a gas-shocking exfoliation strategy was proposed for the in-situ introduction of a π-electron-conjugated structure into ultrathin g-C3N4 nanosheets. The optimal 2C-CNS sample was endowed with a porous-ultrathin-nanosheets morphology (3–4 nm thickness), larger exposed surface area (144.1 m2/g), and significant pore volume (0.51 cm3/g). Using urotropin-deflagration and gas-shocking-driven processes, the precursors were dissociated and copolymerized in an aqueous solution into g-C3N4 nanosheets chemically modified with conjugated carbon moieties. Most importantly, an expanded π-electron conjugated system was successfully constructed between the carbon moieties that interacted with the ultrathin g-C3N4 (2C-CNS), which endowed its with a faster electron-hole separation efficiency and enhanced visible-light harvesting ability. The H2 evolution rate and Cr6+ reduction efficiency for 2C-CNS reached 2360 μmol h−1 g−1 for k = 0.0301 min−1, which was almost 25.8/23 times higher than that of bulk g-C3N4 (Bu-CN, 91.2 μmol h−1 g−1, k = 0.0013 min−1). Also, 2C-CNS showed 2.8/2.4 times higher performance than the g-C3N4 ultrathin nanosheets without a carbon-section modification (0C-CNS, 853 μmol h−1 g−1, k = 0.0125 min−1).