Metal-organic framework coordinated with g-C3N4 and metal ions for boosting photocatalytic H2 production under sunlight

We aim to develop g-C3N4@Ca/UiO-66 and g-C3N4@Co/UiO-66 nanocomposites for photocatalytic hydrogen production by using water and sunlight. Our experiments were performed in a 250 ml glass reactor at room temperature and in vacuum conditions using the solvothermal method. The properties of nanocomposites were characterised by XRD, UV-vis DRS, XPS, RAMAN, DLS, PL, FE-SEM, TEM, AFM, TGA, BET, EDS, ICP, EIS, and Transient photocurrent analyses. The result showed that the highest amount of hydrogen production was 178.3 mu mol/h for g-C3N4@Ca/UiO-66 and 165.9 mu mol/h for g-C3N4@Co/UiO-66. Reusability testing demonstrated that after 4 successive phases of sequential use, the hydrogen photocatalytic production capacity was reduced by about 10 %. Additionally, the AQE value for g-C3N4@Co/UiO-66 was 12.88 % and for g-C3N4@Ca/UiO-66 was 13.85 %. The Z-Scheme mechanism as a charge transfer pathway in the nanocomposites showed that g-C3N4 acts as an electron donor, M/UiO-66 acts as an electron receptor, and the sacrificial reagents act as hole consumers. In general, increasing the unsaturated metal sites, the use of guest metal ions, the presence of aromatic rings in organic ligands, and high specific surface area all increase the interaction between the network and hydrogen molecules. Our synthesized nanocomposites combine all these factors.