Enhancing oxygen reduction reaction activity and stability of platinum via oxide-carbon composites

• DOI: 10.1016/j.cattod.2012.03.033
• Publication Date: 2012-04-19T14:44:46Z
• Authors: B. Ruiz Camacho; C. Morais; M.A. Valenzuela; N. Alonso-Vante
• Keywords: [CHIM.OTHE] Chemical Sciences/Other; [CHIM.ORGA]Chemical Sciences/Organic chemistry; [CHIM.CATA] Chemical Sciences/Catalysis; [CHIM.CATA]Chemical Sciences/Catalysis; [CHIM.ORGA] Chemical Sciences/Organic chemistry; [CHIM.OTHE]Chemical Sciences/Other; 01 natural sciences; 7. Clean energy; 0104 chemical sciences

Abstract A series of oxide-carbon composites using three different oxides (TiO2, SnO2, ZnO) has been prepared using sol–gel (SG) and/or precipitation (P) chemical methods. A selective platinum deposition onto the oxide sites to obtain Pt/TiO2-C, Pt/SnO2-C and Pt/ZnO-C was carried out by generating electron–hole pairs on the oxide under UV-irradiation. This process takes advantage of the photogenerated electron on the oxide in the composite to reduce noble metal anions [PtCl6]2− to Pt0 in the presence of a sacrificial electron donor. The Pt/oxide-carbon materials were characterized by XRD, TEM and CO stripping voltammetry combined with in situ infrared reflection absorption spectroscopy (FTIRS). The electrochemical stability of the different Pt/oxide-C catalysts was investigated by cyclic voltammetry in sulfuric acid medium and their electrochemical activity was evaluated in the oxygen reduction reaction (ORR) at RT. The Pt/oxide-carbon materials showed higher ORR activity than Pt/C catalyst. In situ FTIR spectroscopy coupled with CO stripping voltammetry reveals that CO oxidation on Pt/TiO2-C and Pt/SnO2-C samples takes place at lower electrode potentials as compared to Pt/C. Under the same conditions, the electrochemical stability of platinum center is higher on TiO2-C and SnO2-C composites than ZnO-C and C substrates.