Highly durable isotypic heterojunction generated by covalent cross-linking with organic linkers for improving visible-light-driven photocatalytic performance

A facile and efficient strategy via a cross-linking reaction with organic linkers was proposed to design and synthesize novel isotypic heterojunctions (CN-T/CN-M) based on graphitic carbon nitride (CN) derived from different monomers, which shows superior photocatalytic activity and high stability. [Display omitted] •A strategy based on cross-linking reaction was proposed for fabrication of CN-T/CN-M isotypic heterojunction.•The as-prepared CN-T/CN-M shows superior photocatalytic performance of hydrogen evolution.•The role of as-formed amide covalent bonds in CN-T/CN-M was well investigated.•CN-T/CN-M exhibits high stability and reusability during the catalytic reaction.•A mechanism for enhanced photocatalytic hydrogen evolution over CN-T/CN-M was proposed. Herein, a facile and efficient strategy was proposed to design and synthesize novel isotypic heterojunctions (CN-T/CN-M) based on graphitic carbon nitride (CN) derived from different monomers via cross-linking reaction with organic linkers. DFT calculations and transient spectra analyses elucidated that integration of single CN layers via chemical amide condensation can not only reduce the defective -NH2 groups that act as charge recombination sites but also extend the large delocalized π-electron systems, leading to a suitable internal electric field to efficiently promote migration of photogenerated carriers. Consequently, compared with the individual CN components and their heterostructure prepared by conventional method, CN-T/CN-M shows superior photocatalytic activity of H2 evolution and higher stability under visible light irradiation. Furthermore, an enhanced photocatalytic mechanism was proposed. This work develops a new avenue via covalent cross-linking reaction to construct efficient and stable heterostructured catalysts and provides new idea to design isotypic heterojunction with excellent photocatalytic performance.