Hydrothermally synthesized Cu x O as a catalyst for CO oxidation

Hydrothermally synthesized Cu x O exhibited improved performance for CO oxidation compared to the hydrothermally synthesized Cu 2 O, as well as commercial CuO nanoparticles. Hydrothermally synthesized Cu x O predominantly consists of CuO, but it also contains a small contribution from Cu 2 O, as well as Cu 2 (OH) 3 (NO 3 ) (before annealing). After annealing, only CuO and Cu 2 O phases are present, and the T 50 value is significantly improved from 179 °C to 149 °C, and the T 50 value of annealed hydrothermal Cu x O remains practically unchanged for 3 catalytic cycles. The improved performance of hydrothermal Cu x O 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 Cu 2 O irreversibly changes to CuO after CO oxidation reaction, but its catalytic performance after the first cycle is significantly improved compared to commercial CuO nanoparticles.