Investigation of Pt-Nb-NbOx Loaded on TiN As Cost-Effective Electrocatalyst for Polymer Electrolyte Membranes Fuel Cell

Abstract

Proton Exchange Membrane Fuel Cells (PEMFC) play a key hole for sustainable energy, due its low temperature operation and high potential for automotive and stationary-application. Although, catalyst degradation remains one of the main challenges for PEMFC commercialization. The commercial available electrocatalyst based on Pt/C is susceptible to Pt dissolution and carbon supports corrosion [1]. In this context, we have defined an alternative electrocatalyst for PEM Fuel Cells based on Pt/Nb-NbOx loaded on TiN nanoparticles. Alloying Pt to Nb-NbOx is expected to reduce materials costs by lowering Pt amount [2], while the use of TiN nanoparticles as catalyst support is expected to increase support stability and durability [3]. The Pt/Nb-NbOx loaded on TiN electrocatalyst was successfully synthesized in a one-step process using Reactive Spray Deposition Technology (RSDT). RSDT is breakthrough process for deposition of small catalyst particles with significantly lower production costs while maintaining maximum efficiency [4]. A homogeneous nanostructured electrocatalyst layer of ca. 5 μm thickness was grown on nafion membrane (Figure 1 a). A Pt/Nb-NbOx catalyst content of 7.6 wt.% and 15 wt.% with 0.045 mg∙cm-2 and 0.90 mg∙cm-2 Pt loading respectively were achieved. The catalyst composition was measured by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and double-checked by X-ray Energy Dispersive Spectroscopy (EDS). The electrocatalyst activity was evaluated by Rotating Disk Electrode toward Oxygen Reduction Reaction (ORR). RDE results (Figure 1 b) show that an half-wave potential of 78 mV and 89 mV was achieved for 7.6 wt.% and 15 wt.% Pt/Nb-NbOx catalyst, respectively. Preliminary results suggest that Pt/Nb-NbOx loaded on TiN nanoparticles have electrochemical performance comparable to the state of art Pt/C electrocatalyst [5] and may be a suitable catalyst for PEMFC. Further evaluation regarding Pt-Nb-Ti metal and metal oxide interactions as well as electrochemical performance and durability are in the way and will be discussed.