Synthesis of high-area chemically modified electrodes using microwave heating

The synthesis of dimensionally stable carbon-based chemically modified electrodes (CMEs) is a challenge. The synthesis method, the electrode composition, and the heating used influences various properties of the electrodes. Here, we show an innovative, low cost, and efficient heating method for the CMEs production. We deposited ternary ruthenium, antimony, and tantalum or bismuth oxides on carbon-felts by the Pechini method focusing on the influence of different heating methods (conventional and microwave) on their electrochemical and physical properties. The oxides synthesized using microwave heating coated completely the carbon-felts fibers, displaying homogeneous morphology, while maintaining their three-dimensional character. XRD and XRF analyses confirm the presence of the desired oxides on the coating surfaces and the experimental metal load values close to the nominal (87-91% for Ru, 3-6% for Sb, and 4-7% for Ta or Bi, respectively). The microwave-assisted method yields CMEs with electrochemical active areas 136-fold (for tantalum-based) and 153-fold (for bismuth-based) higher than the unmodified carbon felt. The service lifetime of the CMEs is almost twice as high when using microwave heating than when using conventional heating, which is attributed to the complete and homogeneous coating of the fibers obtained using this heating method. In contrast, the conventional heating led to the incomplete covering of the fibers and to CMEs with low stability. Therefore, the use of microwave heating for the CMEs synthesis reduces the production time at around 60%, thus decreasing the production costs and producing CMEs with improved quality and stability when compared to both conventional-made CMEs and unmodified electrodes.