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

Abstract

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 (XCO2 = 97.42 %, SCH4 = 99.29 %) compared to M−10N7CT (XCO2 = 91.45 %, SCH4 = 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 (Ov). An optimal reaction temperature of 350 °C and gas hourly space velocity of 9,400 mL gcat-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.