A novel copper(II) aspirinate complex easily deposited onto nanotubes of Ti/TiO 2 was successfully employed in the conversion of CO 2 to methanol through the use of UV-Vis irradiation coupled to a bias potential of −0.35 V vs saturated calomel electrode. An average concentration of 0.8 mmol L −1 of methanol was obtained in 0.1 mol L −1 of sodium sulfate saturated with CO 2 using a self-organized Ti/ TiO 2 nanotubular array electrode coated with a [Cu 2 (asp) 4 ] complex. The influence exerted by CO 2 and the complex over the behavior of photocurrent vs potential curves is discussed. Furthermore, a complete investigation of all parameters that tend to influence the global process of methanol production by the photoelectrocatalytic method such as applied potential, electrolyte, and time is also thoroughly presented.

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The present work seeks to describe a new approach characterized by copper(II) aspirinate complex deposited onto nanotube TiO 2 electrodes as mediator of electron transfer during nitrite reduction, aiming at achieving a faster removal of nitrite to nitrogen species oxides. Thin films of copper aspirinate ([Cu 2 (asp) 4 ]) on the Ti/TiO 2 nanotube surface are easily obtained following multi-scans (100 cycles) recorded for the Ti/TiO 2 electrode in 0.1 mol L −1 NaCl, pH 4, containing 5.0 × 10 −4 mol L −1 of the copper coordination compound. The complex showed high adherence while the cyclic voltammograms presented redox peaks at −0.15/+ 0.15 V, which was attributed to the reduction of Cu(II) to Cu(I). Following 5 min of treatment using photoelectrocatalysis on Ti/TiO 2-[(Cu) 2 Asp 4 ] electrode, a total removal of nitrite was observed, which was found to be at least four times faster compared to Ti/ TiO 2 electrode. Concomitantly, we also observed a relatively good conversion to nitrogen-containing gaseous species (56 %) besides the formation of 42 % of ammonia. The results, in effect, also indicate that nitrate and nitrite are not detectable in the treated solution up to levels of 0.5 mg L −1. The method under consideration has successfully accounted for the maximum limit of nitrite recommended in drinking water which has been set to 1 mg L −1 .