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Proton exchange membrane fuel cells (PEMFC) play a key role for sustainable energy; however, catalyst degradation remains one of the main challenges for competing with traditional energy technologies. The Pt/C commercially available electrocatalysts are susceptible to Pt dissolution and carbon support corrosion. In this context, we design a Pt–NbOx catalyst supported on TiN nanoparticles as an alternative electrocatalyst for the oxygen reduction reaction (ORR). The use of Pt–NbOx reduces materials’ costs by lowering the required platinum loading and improving catalyst performance. The TiN support is selected to improve support stability. The electrocatalyst is successfully synthesized by a one-step flame spray process called reactive spray deposition technology. Electrocatalyst with two different very low Pt loadings (0.032 mg cm−2 and 0.077 mg cm−2) are investigated and their performance as cathode is evaluated by the rotating disk electrode method. The new electrocatalyst based on Pt–NbOx supported on TiN has ORR performance that is comparable to the state-of-the-art Pt/C electrocatalyst. A half-wave potential of 910 mV was observed in the polarization curves, as well as a mass activity of 0.120 A∙mgPt−1 and a specific activity of 283 μA∙cmPt−2 at 0.9 V. These results demonstrate that Pt–NbOx on TiN electrocatalyst has the potential for replacing Pt/C cathode in PEMFC.

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A novel method based on correlative microscopy for analyzing metal-rich particulate impurities randomly distributed in large volumes of carbon black powder is described here. Approximately 5 g of carbon black of tap density of 0.075 g cm −3 was used. The powder was encapsulated in epoxy and a combination of 3D X-ray computed tomography (X-CT), laser/ion beam milling and energy dispersive X-ray spectroscopy (EDS) was used to locate and analyze particles of interest. The locations of impurities were identified using X-CT and a focused ion beam (FIB) system with ion and laser beam milling capabilities was then used to analyze regions of interest in the encapsulated sample. The use of a nanosecond pulsed laser for milling allowed for enhanced material removal rates of up to 3 × 10 5 μm 3 s −1 . Finally, scanning electron microscopy (SEM) and EDS were used to image and analyze the composition of the exposed particles. This correlative workflow is shown to be capable of providing detailed spatial, morphological and compositional information about large metal-rich impurities in a carbon black product or a device with carbon black as additives, which may be used for identifying the source of impurities or predicting failure modes in the device.