Boosting photocatalytic H2 evolution by ingenious construction of isotype heptazine/triazine based porous carbon nitride heterojunction

Design and construction of isotype g-C3N4 heterojunction with lower interfacial resistance was a feasible and promising option to achieve the efficient separation of photo-induced electron-holes pairs. However, isotype g-C3N4 heterojunction prepared by direct thermal polymerization usually possessed low specific surface area, which limited the further elevation of photocatalytic performance. In this work, isotype heptazine/triazine based carbon nitride heterojunction (HTCN-1M) with high surface area was prepared by molten salt method which employed heated H2SO4-pretreated melamine as the precursor. The abundant specific surface area (180 m2 g−1) was ascribed to the pore-making effect of H2SO4 and the templating of molten salt while the efficient transfer and separation of photo-generated charge carriers were attributed to the built-in electric field of the heterojunction structure, whose synergistic effect resulted in the excellent photocatalytic performance of H2 evolution, reaching up to 5764 μmol h−1 g−1, which was 19.4 times that of pure g-C3N4. This work provided a new avenue for the design of efficient photocatalysts for the conversion of solar energy.