Interface Reconstruction of Rod-like Cu 3 (HHTP) 2 /In 2 S 3 S-Type Heterojunctions: Pore Structure Preservation and Regulation of Charge Carrier Dynamics in Photocatalytic CO 2 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, Cu 3 (HHTP) 2, with In 2 S 3 to synergistically improve photocatalytic activity. Unlike conventional flake-like heterojunctions that often block the vertical pore channels of c -MOFs, we synthesized rod-like Cu 3 (HHTP) 2 /In 2 S 3 composites through controlled morphological engineering. Experimental results demonstrate the resulting nonplanar interfacial contact effectively preserves the intrinsic pore architecture while fully exposing the d z 2 orbitals of Cu active centers. Structural analyses reveal that the rod-like Cu 3 (HHTP) 2 interacts with In 2 S 3 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 CO 2 adsorption capacity reaches 13.44 cm 3 ·g –1, 2.18 times higher than that of the flake-like Cu 3 (HHTP) 2 /In 2 S 3 composite that In 2 S 3 is bonded via Cu–S bonds on the surface. Moreover, the incorporation of In 2 S 3 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 In 2 S 3, leading to significantly improved electrical conductivity and charge separation efficiency.