Novel double-layer core–shell photocatalyst CdS–TiO2@NH2-MIL-101: enhanced conversion of CO2 and CH4 at ambient temperature†

The conversion of CO₂ and CH₄ into high value-added chemical products by chemical means is regarded as an emerging industrial technology to solve the increasingly serious climate and energy crises. The solar-powered conversion of CO₂ and CH₄ to syngas is one such technology that holds promise for the production of renewable fuels. Here, ternary core–shell CdS–TiO₂@NH₂-MIL-101 composites were prepared using mild experimental methods and their physical and chemical properties were studied using a series of characterization methods. In addition, the interaction between the coupling of different mass fractions of MOF, TiO₂, and CdS and the performance of photocatalytic, photothermal, and thermocatalytic CH₄ reforming were investigated. The results show that the yields of CO and H₂ of the CdS–TiO₂@NH₂-MIL-101 catalyst at room temperature are 364.46 μmol g⁻¹ and 100.43 μmol g⁻¹, respectively, which are 1200–1500% of the catalytic performance of TiO₂. Moreover, the yields of CO and H₂ of the CdS–TiO₂@NH₂-MIL-101 material at 150 °C are 2831.55 μmol g⁻¹ and 1448.20 μmol g⁻¹, respectively. Based on isotope tracer experiments and CO₂ adsorption experiments, a possible comprehensive mechanism for CdS–TiO₂@NH₂-MIL-101 photocatalytic CH₄ reforming is proposed. In addition to presenting a fresh research concept for achieving carbon neutrality, this work offers a new technical pathway for the quick conversion of CO₂ and CH₄ at room temperature.