Interface Reconstruction of Rod-like Cu3(HHTP)2/In2S3 S-Type Heterojunctions: Pore Structure Preservation and Regulation of Charge Carrier Dynamics in Photocatalytic CO2 Reduction

Constructing S-scheme heterojunctions on two-dimensional (2D) conductive metal–organic frameworks (c-MOFs), which possess high specific surface area, abundant active sites, and excellent electrical conductivity, is widely regarded as an effective strategy to enhance photocatalytic performance. In this study, an S-type heterojunction was fabricated by coupling a 2D c-MOF, Cu3(HHTP)2, with In2S3 to synergistically improve photocatalytic activity. Unlike conventional flake-like heterojunctions that often block the vertical pore channels of c-MOFs, we synthesized rod-like Cu3(HHTP)2/In2S3 composites through controlled morphological engineering. Experimental results demonstrate the resulting nonplanar interfacial contact effectively preserves the intrinsic pore architecture while fully exposing the dz2 orbitals of Cu active centers. Structural analyses reveal that the rod-like Cu3(HHTP)2 interacts with In2S3 predominantly via In–O bonds formed on its lateral facets, thereby maintaining the inherent porosity and exposing a large number of active sites. Consequently, the CO2 adsorption capacity reaches 13.44 cm3·g–1, 2.18 times higher than that of the flake-like Cu3(HHTP)2/In2S3 composite that In2S3 is bonded via Cu–S bonds on the surface. Moreover, the incorporation of In2S3 enhances interlayer charge transport within the rod-like structure. As a result of these synergistic effects, the electron consumption rate of the rod-like heterojunction is 1.73 times greater than that of its flake-like counterpart. The unique architecture not only retains the in-plane charge transport advantages derived from d-π conjugation in c-MOFs but also introduces interlayer electron-bridging pathways through In2S3, leading to significantly improved electrical conductivity and charge separation efficiency.