Activity and stability studies of titanates and titanate-carbon nanotubes supported Ag anode catalysts for direct methanol fuel cell Mohamed Mokhtar Mohamed *, M. Khairy, Salah Eid Benha University, Faculty of Science, Chemistry Department, Benha, Egypt H I G H L I G H T S • Ag/titanate and Ag/titanate-CNT are fabricated using deposition- photo-irradiation process. • Ag/titanate exhibited the highest performance towards MOR. • Strong metal–support interactions exist between Ag particles and titanate support. • The enhancement was due to the high surface area and the modified electron structure. • Electrocatalytic enhancement for Ag/titanate is mainly via bifunctional mechanism. G R A P H I CA L A B ST R AC T ARTICLE INFO Article history: Received 15 September 2015 Received in revised form 26 October 2015 Accepted 16 November 2015 Available online 6 December 2015 Keywords: Ag/titanate-SWCNT Direct methanol fuel cells Electrocatalysis Electrochemical impedance Electrical conductivity A B ST R AC T Titanate-SWCNT; synthesized via exploiting the interaction between TiO2 anatase with oxygen functionalized SWCNT, supported Ag nanoparticles and Ag/titanate are characterized using XRD, TEM-EDX-SAED, N2 ad- sorption, Photoluminescence, Raman and FTIR spectroscopy. These samples are tested for methanol electrooxidation via using cyclic voltammetry (CV) and impedance measurements. It is shown that Ag/ titanate nanotubes exhibited superior electrocatalytic performance for methanol oxidation (4.2 mA cm -2 ) than titanate-SWCNT, Ag/titanate-SWCNT and titanate. This study reveals the existence of a strong metal- support interaction in Ag/titanate as explored via formation of Ti–O–Ag bond at 896 cm -1 and increasing surface area and pore volume (103 m 2 g -1 , 0.21 cm 3 g -1 ) compared to Ag/titanate-SWCNT (71 m 2 g -1 , 0.175 cm 3 g -1 ) that suffers perturbation and defects following incorporation of SWCNT and Ag. Embed- ding Ag preferably in SWCNT rather than titanate in Ag/titanate-SWCNT disturbs the electron transfer compared to Ag/titanate. Charge transfer resistance depicted from Nyquist impedance plots is found in the order of titanate > Ag/titanate-SWCNT > titanate-SWCNT > Ag/titanate. Accordingly, Ag/titanate in- dicates a slower current degradation over time compared to rest of catalysts. Conductivity measurements indicate that it follows the order Ag/titanate > Ag/titanate-SWCNT > titanate > titanate-SWCNT declar- ing that SWCNT affects seriously the conductivity of Ag(titanate) due to perturbations caused in titanate and sinking of electrons committed by Ag o through SWCNT. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Titania is one of common oxides used in Direct methanol fuel cells (DMFCs) due to its low cost and inherent stability in an * Corresponding author. Postal Code: 13511, Egypt. E-mail address: mohmok2000@yahoo.com (M.M. Mohamed). http://dx.doi.org/10.1016/j.jpowsour.2015.11.054 0378-7753/© 2015 Elsevier B.V. All rights reserved. Journal of Power Sources 304 (2016) 255–265 Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour