Chlorine-mediated synthesis of self-exfoliated and wavy-structured graphitic carbon nitride nanosheets for enhanced photocatalytic hydrogen evolution

Abstract

Graphitic carbon nitride (GCN) has drawn widespread interests in solar hydrogen production. However, the difficult exfoliation and the intrinsic shortcomings greatly restrict the hydrogen production efficiency. Herein, we report a chlorine-mediated strategy to synthesize ultrathin wavy-structured GCN nanosheets for enhancing photocatalytic activity. Chlorine is firstly doped into the melem-based oligomer; in subsequent polymerization process, self-exfoliated wavy-structured GCN are obtained owing to the effect from chlorine removal. The obtained wavy-GCN presents superior H2 evolution rate at 3372 μmol·g−1 h−1, which is 25 times higher than pristine GCN. Comprehensive characterizations reveal two main reasons for the enhanced photocatalytic activity. 1) The GCN is in-situ self-exfoliated owing to removal of doped chlorine, increasing accessible active sites. 2) The introduction of nitrogen-defects into GCN gives rise to enhanced light absorption capacity and reduced charge carriers recombination rate. This work provides a new bottom-up two-step strategy for structural regulation of GCN towards enhanced photocatalytic performance.