Hydrothermally synthesized CuxO as a catalyst for CO oxidation

Hydrothermally synthesized CuxO exhibited improved performance for CO oxidation compared to the hydrothermally synthesized Cu2O, as well as commercial CuO nanoparticles. Hydrothermally synthesized CuxO predominantly consists of CuO, but it also contains a small contribution from Cu2O, as well as Cu-2(OH)(3)(NO3) (before annealing). After annealing, only CuO and Cu2O phases are present, and the T-50 value is significantly improved from 179 degrees C to 149 degrees C, and the T-50 value of annealed hydrothermal CuxO remains practically unchanged for 3 catalytic cycles. The improved performance of hydrothermal CuxO can be attributed to its composition and surface properties. The ratio of lattice oxygen to surface oxygen (oxygen in surface adsorbates, surface states, and defects) increases after the first CO oxidation reaction for all samples except commercial CuO nanoparticles, which exhibit steady decrease with increased cycling. In addition, pure Cu2O irreversibly changes to CuO after CO oxidation reaction, but its catalytic performance after the first cycle is significantly improved compared to commercial CuO nanoparticles.