Visible-Light-Driven Efficient Hydrogen and Methanol Production Using 2D/3D SnS ₂ /Covalent Organic Framework Heterojunctions as Catalyst

Imine-linked three-dimensional covalent organic frameworks (3D COFs) with donor–acceptor motifs are attractive photocatalysts but are often limited by narrow band gap tunability, inefficient charge separation, and few accessible active sites. Here, we report a 2D/3D heterostructure photocatalyst formed by in situ anchoring ultrathin SnS2 nanosheets (∼10 nm) onto a robust 3D TT-COF via a scalable hydrothermal method. The resulting SnS2/TT-COF (TTSN-COF) exhibits exceptional activity for both visible-light-driven H2 evolution and reduction of CO2 to methanol. DFT calculations reveal a favorable hydrogen adsorption free energy (ΔGH* = −0.87 eV) together with enhanced CO2 adsorption energy (ΔEads = −73.6 kJ mol–1) for the SnS2/TT-COF heterojunction, indicating accelerated reaction kinetics driven by efficient interfacial charge transfer. Experimentally, TTSN-COF delivers a hydrogen evolution rate of 5500 μmol g–1 (8 h) and a methanol production rate of 1280 μmol g–1 in (6 h), far exceeding the performance of the individual components. The catalyst also demonstrates excellent durability, maintaining >85% of its initial activity after 20 h of continuous irradiation. These results establish the SnS2/TT-COF heterostructure as a benchmark platform for efficient solar-driven hydrogen generation and CO2 valorization.