Photoelectrocatalysis has being shown to be a good technique in CO2 reduction contributing with a great concern that is hearth climate [1,2]. Thus, the present work compares the performance of semiconductors Cu/Cu2O, NTTiO2/Pt (nanotubes of Ti/TiO2/Pt) and Ti/TiO2/CuO p-n junction on the photoelectrocatalytic CO2 reduction and compares its contribution on the different kind of generated products. The morphological and structural characterization of all synthesized semiconductors were carried out by XRD, EDS and FEG-SEM analysis. The photocurrent response was evaluated by LSV in NaHCO3 0.1 molL-1 with and without CO2 using similar geometric areas. The photoelectrochemical experiments were performed in a two-compartment reactor, where the semiconductor was irradiated by UV-Vis light (125 W) and submitted to controlled-potential. Pt gauze was used as counter electrode and an Ag/AgCl (KCl sat) as reference. The probably products formation of methanol, ethanol, acetaldehyde, formaldehyde and acetone were identified and quantified by CG-FID (CP-3800 Varian) and HPLC-DAD (Shimadzu 10AVP). The photocurrent response for the entire semiconductors in presence of CO2 and UV–Vis light presented a high photocathodic currents attributed to CO2 photoreduction. The phototelectrocatalytic CO2 reduction performance on Cu/CuO, NTTiO2/Pt and Ti/TiO2/CuO semiconductors were accomplished evaluating the applied potential, supporting electrolyte type, pH and concentration of supporting electrolyte. In the case of Cu/Cu2O semiconductor, 96% of faradaic efficiency was obtained for methanol (5.50 mmol L-1) formation, however a small useful life of the electrode was observed. The products methanol (0.29 mmol L-1), ethanol (0.025 mmol L-1) and acetone (0.004 mmol L-1) were quantified applying Ti/TiO2/CuO with a long life of the semiconductor, but only 5% of faradaic efficiency was achieved. In addition, for the NTTiO2/Pt semiconductor, it has been shown as a not good option for CO2 reduction, due the strong adsorption of the intermediate poisoning the electrode surface. The mechanism of product formation is discussed. References [1] S. Hangx, CATO Work. WP. 1 (2005) 1–43. [2] S. Ohya, et al., Catal. Today. 148 (2009) 329–334. [3] J. F. de Brito, et al., Int. J. Electrochem. Sci., 9 (2014) 5961 – 5973. [4] L. C. Almeida, M. V. B. Zanoni, J. Braz. Chem. Soc., 25, (2014), 579-588. [5] L. Perazolli, et al., Mater. Sci. Appl. 2 (2011) 564-571.

Influence of electrode materials in the photoelectrocatalytic CO2 reduction

251st National Meeting (2016)

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