Well-Designed morphology regulated ZIF-67 derived 0D/1D Co₃O₄@TiO₂ NWs integrated with in-situ grown Ni/Co-Active metals for Low-Temperature driven CO₂ methanation

Well-designed morphology regulated MOF-templated Co₃O₄ over titanium dioxide nanowires (TiO₂ NWs) boasting intimate interfacial contact for highly efficient CO₂ methanation was synthesized via a facile in-situ grown approach. The synergistic effect of 0D Co₃O₄ with reducible 1D TiO₂ NWs and the role of Ni/Co-active metals were systematically investigated for CO₂ methanation. The performance comparison of the Ni dispersed in-situ grown Co₃O₄ on TiO₂ NWs (Insitu-10N7CT) and its mechanically assembled counterpart (M−10N7CT) was further explored. The in-situ grown ZIF-67 acts as a sacrificial template to produce Co₃O₄ with high dispersion of Ni active sites to enhance CH₄ production. By regulating the morphology, 0D Co₃O₄ promoted a superior methanation performance for Insitu-10N7CT (X_CO2 = 97.42 %, S_CH4 = 99.29 %) compared to M−10N7CT (X_CO2 = 91.45 %, S_CH4 = 98.42) due to intimate interfacial contact between the Ni, Co, and Ti species. Comparatively, the MOF-derived composites displayed much higher CH₄ yield than uncalcined MOF nanocomposites. This is because the high reaction temperature caused a rapid collapse of the ZIF-67 dodecahedral structure, leading to a lower methanation performance. Insitu-10N7CT exhibited higher reducibility, generating low valence oxidation/metallic states of Ni-Co-Ti, leading to the high density of oxygen vacancies (O_v). An optimal reaction temperature of 350 °C and gas hourly space velocity of 9,400 mL g_cat^-1h⁻¹ was revealed, suggesting an efficient reactant contact and CO₂ conversion into CH₄. The Insitu-10N7CT composite exhibited durability up to 100-hour time-on-stream due to the gradual reduction of Co₃O₄. Thus, the novel MOF-templated ternary nanocomposite revealed a facile method for regulating the structure of MOF derivatives while boosting strong interfacial interactions for efficient renewable fuel production.