Charge transfer dependence on CO2 hydrogenation activity to methanol in Cu nanoparticles covered with metal–organic framework systems†
We report the synthesis and characterization of highly active Cu nanoparticles covered with zirconium/hafnium-based metal–organic frameworks for CO2 hydrogenation to methanol. Compared to Cu/γ-Al2O3, Cu/ZIF-8, Cu/MIL-100 and Cu/UiO-66 composites, UiO-66 acts as the most active support, with Cu/Zr-UiO-66 producing methanol at a rate 70 times higher than that of Cu/γ-Al2O3. In addition, the replacement of Zr4+ with Hf4+ in UiO-66 tripled in the rate of methanol production. Furthermore, we describe a substituent effect on the catalytic activity, with Cu/Zr-UiO66-COOH providing a three-fold enhancement of methanol production, compared to that of Zr-UiO-66 or Zr-UiO66-NH2. The enhanced catalytic activity of Cu nanoparticles depends on the charge transfer degree from Cu nanoparticles to UiO-66 at the interface between Cu nanoparticles and UiO-66.