The hunt for platinum’s successor as a hydrogen oxidation catalyst continues in this month’s Nature Communications (Zhuang, Z. et al. Nickel supported on nitrogen-doped carbon nanotubes as hydrogen oxidation reaction catalyst in alkaline electrolyte. Nat. Commun. 7:10141 doi: 10.1038/ncomms10141 (2016)).
A research team from the University of Delaware, in partnership with Beijing University of Chemical Technology, have made a breakthrough in their search for a low-cost catalytic material. After switching from an acidic to an alkaline environment, the researchers experimented with nickel nanoparticles supported on nitrogen-doped carbon nanotubes. According to their results, this composite catalyst can produce a hydrogen oxidation activity comparable to platinum-group metals in alkaline electrolyte. In their words,
Although nitrogen-doped carbon nanotubes are a very poor hydrogen oxidation catalyst, as a support, it increases the catalytic performance of nickel nanoparticles by a factor of 33 (mass activity) or 21 (exchange current density) relative to unsupported nickel nanoparticles. Density functional theory calculations indicate that the nitrogen-doped support stabilizes the nanoparticle against reconstruction, while nitrogen located at the edge of the nanoparticle tunes local adsorption sites by affecting the d-orbitals of nickel. Owing to its high activity and low cost, our catalyst shows significant potential for use in low-cost, high-performance fuel cells.
The team’s results suggest that when the nitrogen dopants sit at the edge of the nickel nanoparticles, it stabilises and activates the nickel. By multiplying the catalytic effect of the nickel, the nitrogen-doped nanotubes thus bring the cost of the catalyst down to competitive levels.
Finding a cheap alternative catalyst to platinum is one of the necessary steps in scaling up a full-scale hydrogen economy. In a press release, contributing author Yushan Yan expressed his hope that his team’s results would be a step towards that goal,