Insights into the role of CuO in the CO(2) photoreduction process

The CO(2) photoreduction process to produce light hydrocarbons is known to be influenced by the presence of CuO nanoparticles, but the actual role of this material, whether as a catalyst or a reactant, has not yet been revealed. In this work, we investigate the role of CuO nanoparticles produced by a solvothermal method as a catalyst in CO(2)-saturated water reaction media under UV light, considering the effects of different electrolytes (Na(2)C(2)O(4), KBrO(3), and NaOH) and temperatures on nanoparticle phase and activity. The electrolyte strongly influenced product selectivity (NaOH led to evolution of CH(4), Na(2)C(2)O(4) to CO, and KBrO(3) to O(2)) and induced CuO phase change. A long-term analysis of these processes indicated that during the initial steps, CuO acted as a reactant, rather than as a catalyst, and was converted to CuCO(3).Cu(OH)(2), while the as-converted material acted as a catalyst in CO(2) photoreduction, with conversion values comparable to those reported in the literature.