Synthesis and electrocatalytic assessment of precursor derived TiN/Si-Al-C-N ceramic nanocomposites for oxygen reduction reaction

Eranezhuth Wasan Awin^a, Timon E^b. Günther^b, Rameshwori Loukrakpam^b, Christina Roth^b, Günter Motz^a

^aDepartment of Ceramic Materials Engineering, University of Bayreuth, Prof.-Rüdiger-Bormann-Str. 1, 95447 Bayreuth, Germany

^bUniversität Bayreuth, Fakultät für Ingenieurwissenschaften, Lehrstuhl für Werkstoffverfahrenstechnik, 95447 Bayreuth, Germany

The global energy demand and environmental pollution drives the need for the augmentation of the existing sustainable energy devices. Out of which, electrocatalytic devices (e.g. fuel cells) have raised considerable interest due to their high energy density and power density. The oxygen reduction reaction (ORR) is an important reaction in electrocatalysis and the platinum based electrocatalysts have been proven to be the best in terms of its performance. Currently, platinum on a carbon support is the most extensively used ORR catalyst. However, the use of noble metals increases the overall cost of the electrocatalytic devices and the platinum based electrocatalysts are also known to be unstable in a fuel cell working conditions. Hence, the development of efficient and durable catalysts is critical for the commercialization of fuel cells, as the catalysts' reactivity and durability dictate their ultimate lifetime and activity.

In this work, amorphous silicon based ceramics (Si-C-N and Si-Al-C-N) and TiN/Si-Al-C-N nanocomposites were developed using a precursor derived ceramics (PDC) approach. The role of synthesis and structure of the ceramics were investigated for its activity towards the ORR. The TiN/Si-Al-C-N nanocomposites synthesized using a combinatorial approach using PDC and urea-glass route was found to be mesoporous in nature. The phase evolution, structural and textural properties of the developed catalytic supports were evaluated with the aid of X-ray diffraction, scanning electron microscopy and nitrogen adsorption analysis. The ORR activity was determined using rotating disk electrode method under alkaline conditions. The ORR current was found to decrease with increase in pyrolysis temperature implying the role of pyrolysis conditions on the ORR activity.