High-density monodispersed nickel nanoparticles as highly functional and thermally robust catalysts for solid oxide fuel cells

In this study, we have explored the deposition of highly monodispersed nickel nanoparticles on various supports using a two-step metal–organic precursor thermolysis and reductive annealing process. The process allowed flexible tunability of application-relevant properties, such as nanoparticle size, density and distribution, via the process pressure and deposition cycle control. Ex-situ characterization revealed the presence of carbon in the nanoparticles, necessitating the reductive annealing step to remove residual carbon. The impurities-free nanoparticles were subsequently deposited onto Pr0.5Ba0.5MnO3−δ anodes of solid oxide fuel cells and used to promote the electrochemical oxidation of methane. Impedance spectroscopy of the symmetric cells (Pr0.5Ba0.5MnO3−δ Yttria-stabilized ZrO2 Pr0.5Ba0.5MnO3−δ) revealed a significant enhancement in the catalytic activity of the Ni nanoparticle-coated electrode relative to the bare reference. Moreover, compared to conventional infiltration, the Ni nanoparticles deposited with the strategy outlined in this work showed over a 4-fold improvement in performance with an initial electrode resistance of only 2.1 Ω cm2. This highlights the important role of the deposition method on catalytic performance and the potential of developing highly active electrode materials for direct-hydrocarbon utilization. [Display omitted] •A two-step metal–organic precursor thermolysis and reductive annealing process for the deposition of highly monodispersed nickel nanoparticles.•Flexible tunability of nanoparticle size, density, and distribution.•Ni nanoparticles used as catalysts in Pr0.5Ba0.5MnO3−δ Yttria-stabilized ZrO2 Pr0.5Ba0.5MnO3−δ solid oxide fuel cells for methane oxidation exhibit ∼9 times decrease in area-specific electrode resistance relative to the bare PBMO reference.•Comparison with Ni nanoparticles deposited by a conventional infiltration process revealed the superior catalytic performance of the Ni nanoparticles (PBMO@Nitwo-step) developed in this work.