A highly active Pt nanocatalysts supported on RuO2 modified TiO2-NTs for methanol electrooxidation with excellent CO tolerance

Poisoning devitalization of Pt catalyst caused by the absorption of carbon monoxide is an important issue in direct Methanol Fuel Cell (DMFC). To solve this problem, this work introduced a novel nano-structured Pt catalytic electrode, in which RuO₂ modified TiO₂ nanotube arrays (TiO₂-NTs) was used as a carrier for the load of Pt nanocatalysts. Specifically, RuCl₃ sol was filled into the voids of TiO₂-NTs under vacuum condition, followed by thermal decomposition to form RuO₂/TiO₂-NTs support, and then Pt particles were loaded on the RuO₂/TiO₂-NTs support by pulse potential electrodeposition from H₂PtCl₆ aqueous solution. The electrochemical results show that the methanol oxidation current on Pt/RuO₂/TiO₂-NTs is much higher than that on Pt/TiO₂-NTs. In addition, the current attenuation on Pt/RuO₂/TiO₂-NTs with the increased scan cycle is also decreased. The Pt/RuO₂/TiO₂-NTs electrode with 8 g m⁻² RuO₂ exhibits the most stable performance, indicating a strong effects of anti CO poisoning endowed by RuO₂. In Nyquist diagrams, one capacitance arc representing the action of deprivation of H atom appears in the first quadrant and one inductance arc representing the action of deprivation of CO appears in the fourth quadrant. From the fitting results, both the reaction resistance R_ct and the inductance L decrease with the argument of RuO₂ content under bias potential of 600 mV, and in this case CO oxidation is the rate controlling step.