Sharply increasing the visible photoreactivity of g-C3N4 by breaking the intralayered hydrogen bonds

Abstract

Photocatalytic H2 production has attracted much attention using visible-light-responsive graphitic carbon nitride (g-C3N4) as photocatalyst. However, two-dimensional g-C3N4 has suffered from poor photocatalytic activity due to numerous intralayered hydrogen bonds and limited visible-light-responsive range. To solve this problem, in this paper, breaking the hydrogen bonds of g-C3N4 by S-doping is reported through poly-condensation of dicyandiamide (DCDA)-thioacetamide (TAA) mixture. The effects of TAA amount on the structure, property and photocatalytic performance of S-doped g-C3N4 are systematically studied. Among all the prepared photocatalysts, sample T0.6, exhibits the highest photoreactivity with a hydrogen production rate of 525.5 µmol g−1 h−1 under the visible light irradiation (λ > 420 nm), which is 7.7-times higher than that of bulk g-C3N4 (BCN). The enhanced photocatalytic hydrogen production is mainly attributed to substituting of sp2-hybridized N with S atoms, which breaks intralayered hydrogen bonds of g-C3N4, resulting in greatly enhanced visible-light-response ability and efficient migration and separation of photo-induced charge carriers by facilitating the n → π* electron transition. In addition, the porous structures of S-doped multi-layered g-C3N4 also provide more reactive sites for water-splitting, which also facilitates the hydrogen production. The present study provides new insights into the design of high efficient g-C3N4-based photocatalyst.