Dopant-Induced Edge and Basal Plane Catalytic Sites on Ultrathin C3N4 Nanosheets for Photocatalytic Water Reduction

The emerging carbon nitride (C3N4) offers a serious possibility for realizing a highly effective hydrogen evolution reaction (HER). However, their insufficient catalytic sites and poor conductivity hamper the HER performance. Herein, an oxygen, phosphorus dual-doped ultrathin C3N4 nanosheet (O, P-CNS) is synthesized through a two-step method without a liquid solution, including calcination under air and subsequent chemical vapor deposition (CVD) with sodium hypophosphite (NaH2PO2) in N-2 atmosphere. The first thermal treatment in the air atmosphere results in the introduction of O dopant on the edge of C3N4 and the exfoliation of bulk C3N4 into ultrathin nanosheets. The following P incorporation contributes to the activation of the basal plane of C3N4 and the improvement of the intrinsic electronic conductivity, thus giving rise to the facilitated H-2 generation rate. Particularly, a superior H-2 generation rate of 8.7 mmol g(-1) h(-1) under visible light and an apparent quantum yield of 23.65% with 420 nm could be realized after the two-step dual-doping-induced calcination, further confirming the enhanced charge separation with the full activation of the edge and basal plane catalytic sites of C3N4. Our work on dual-doping-induced catalytic site activation on the edge and basal plane of C3N4 will provide more guidance in the field of designing C3N4-based photocatalysts.