Assembly-synthesis of puff pastry-like g-C3N4/CdS heterostructure as S-junctions for efficient photocatalytic water splitting

•A self-assembly strategy was employed to construct puff pastry-like h-CN/CdS heterojunction.•Molecular tailoring of g-C3N4 generated hydrolyzed sol as quasi-homogeneous precursor.•As-assembled architecture exhibited 3.5-fold increased activity for hydrogen evolution.•Strong interfacial interactions contributed to the S-scheme charge transfer in reassembles. Designing S-scheme heterojunctions with strong interfacial interaction is an effective way to facilitate the separation of photocarriers, as well as retaining the strong photoredox abilities. Graphitic carbon nitride (g-C3N4) has emerged as a promising material for heterostructure design, but the interfacial hybridization was restricted by the low surface area and limited active sites of bulk g-C3N4. In this paper, a molecular assembly strategy was employed to synthesize puff pastry-like g-C3N4/CdS nanoarchitectures with strongly coupled interfaces. The hydrogen bond-mediated reassembly of hydrolyzed g-C3N4 molecules was employed to intercalate ultrafine CdS nanoparticles into 2D g-C3N4 assemblies. The intimate contact between g-C3N4 supports and inlaid CdS contributed to the formation of built-in electric field, which was favorable for the S-scheme separation of photogenerated carriers. As a consequence, the puff pastry-like g-C3N4/CdS heterojunction exhibited a H2 evolution rate of 3.37 mmol·g−1·h−1. The strategy used here paves a new avenue toward the assembly synthesis of high-performance S-scheme photocatalysts via molecular tailoring.