Exploring the CO2 photocatalytic evolution onto the CuO (1 1 0) surface: A combined theoretical and experimental study

A combined theoretical and experimental study was performed to elucidate the photocatalytic potential of tenorite, CuO (1 1 0) and to assess the evolution pathway of carbon dioxide (CO2) evolution pathway. The calculations were performed with density functional theory (DFT) at a DFT + U + J0 and spin polarized level. The CuO was experimentally synthesized and characterized with structural and optical methodologies. The band structure and density of states revealed the rise of band gaps at 1.24 and 1.03 eV with direct and indirect band gap nature, respectively. These values are in accordance with the experimental evidence at 1.28 and 0.96 eV; respectively, which were obtained by UV-Vis DRS. Such a behavior could be related to enhanced photocatalytic activity among copper oxide materials. Experimental evidence such as SEM images and work function measurements were also performed to evaluate the oxide. The redox potential suggests a catalytic character of tenorite (1 1 0) for the CO2 transformation through aldehydes (methanal) intermediate formation. Furthermore, a route through methylene glycol CH2(OH)2 was also explored with the theoretical methodology. The reaction path exhibits an immediate reduction of ▪ into a •OH radical and an [OH]− anion, in the first step. This •OH radical attacks a double bond (C = O) of ▪ to form bicarbonate ([▪]−) and subsequently, carbonic acid (▪). The carbonic acid reacts with other •OH radical to finally form orthocarbonic acid (▪). •DFT calculations evidenced selective CuO photocatalytic potential in tenorite phase•DFT and experiments revealed the CO2 evolution reaction on CuO (1 1 0) facet.•Theoretical calculations showed •OH radical formation is virtually immediate on CuO.•The carbonic acid is allowed to react with other •OH radical to form orthocarbonic acid.•Theory and experiment evidenced both direct and indirect band gaps in tenorite.