Facile constructing of isotype g-C3N4(bulk)/g-C3N4(nanosheet) heterojunctions through thermal polymerization of single-source glucose-modified melamine: An efficient charge separation system for photocatalytic hydrogen production

Constructing isotype heterostructure is an effective way to promote the separation of photogenerated charge carriers for graphitic carbon nitride (g-C3N4). However, the interface derived from different source precursors is not good enough for the charge separation of g-C3N4/g-C3N4 isotype heterojunctions, resulting in a limited improvement of photocatalytic performance. Here, we presented a rational design and synthesis of the g-C3N4(bulk)/g-C3N4(nanosheet) (denoted as BCN/CNNS) isotype heterojunctions with tight interfaces for enhanced photocatalytic hydrogen evolution. Using glucose-modified melamine as the single-source precursor for the first time, an isotype heterojunction was in situ formed at the interface between bulk g-C3N4 and g-C3N4 nanosheet. Due to the enhanced visible light absorption and promoted charge carrier separation, the in situ formed BCN/CNNS isotype heterojunctions exhibited highly improved photocatalytic hydrogen evolution activity under visible light irradiation, which was 16.4 and 11.5 times than those of the bare BCN and CNNS, respectively. Such an in situ formed isotype heterojunction with tight interfaces originated from the thermal polymerization of single-source glucose-modified melamine would present a new avenue for developing efficient g-C3N4-based isotype heterojunction photocatalysts.