Hierarchical TiN Nanostructured Thin Film Electrode for Highly Stable PEM Fuel Cells

Fuel cells are, to date, on the verge of large-scale commercialization. Still, long-term stability is of concern, especially in the automotive field, mainly because of the cathodic catalyst support. In fact, carbonaceous materials, the state of the art to date, suffer from severe corrosion phenomena during discontinuous operation. In the effort to replace carbon as Pt support and develop a nanoengineered architecture for the fuel cell electrodes, we report here the concept of a hierarchical TiN nanostructured thin film (HTNTF) electrode, in which Pt is deposited on an array of quasi-1D TiN nanostructures with good conductivity, high roughness factor, tunable porosity, and outstanding chemical stability. The HTNTF is grown by self-assembly from the gas phase by means of a one-step, template-free, room-temperature process, namely, pulsed laser-scattered ballistic deposition, PL-SBD. The activity of the nanostructured thin film electrode is assessed toward the oxygen reduction reaction and its stability evaluated according to DOE accelerated stress test (AST) standard protocols, revealing an electrochemical surface area (ECSA) loss as low as 7% with respect to the 40% goal. Moreover, a proof-of-concept cell has been realized to demonstrate the applicability of our supports to the device scale. Despite the fact that further optimization is needed to achieve high performances, this new class of electrodes has clear potential in terms of stability with respect to the state of the art, overcoming carbon corrosion by simply removing it from direct contact with the Pt electrocatalyst.