Tuning the turnover frequency and selectivity of photocatalytic CO2 reduction to CO and methane using platinum and palladium nanoparticles on Ti-Beta zeolites

A Ti-Beta zeolite was used in gas phase photocatalytic CO2 reduction to reduce the charge recombination rate and increase the surface area compared to P25 as commercial benchmark, reaching 607 m2 g−1. By adding Pt nanoparticles, the selectivity can be tuned toward CO, reaching a value of 92% and a turnover frequency (TOF) of 96 μmol·gcat−1·h−1, nearly an order of magnitude higher in comparison with P25. By adding Pd nanoparticles the selectivity can be shifted from CO (70% for a bare Ti-Beta zeolite), toward CH4 as the prevalent species (60%). In this way, the selectivity toward CO or CH4 can be tuned by either using Pt or Pd. The TOF values obtained in this work outperform reported state-of-the-art values in similar research. The improved activity by adding the nanoparticles was attributed to an improved charge separation efficiency, together with a plasmonic contribution of the metal nanoparticles under the applied experimental conditions