Nanostructured Co-B Catalysts for Hydrogen Generation

We have prepared nanostructured Co-B catalysts via electroless deposition on a porous polycarbonate membrane for use as a hydrogen evolution catalyst from a sodium borohydride solution. Amorphous Co-B alloy is deposited to form nanotubes, connected together by a thin film at both ends. We have varied the deposition time to form a range of Co-B nanostructures to maximise hydrogen release. We have found that Co-B nanostructures with low deposition times of 20 s have the largest hydrogen generation rate per unit mass of 11,000 ml min⁻¹ g⁻¹. However, deposition times of 80 s have the largest rate per unit area of 18,000 ml min⁻¹ m⁻². For larger deposition times the nanotube pore diameter decreases which results in a reduction in the hydrogen generation rate, due to a decrease in the catalytic surface area. The activation energy of the Co-B nanostructures is found to be between 40–50 kJ mol⁻¹, indicating that they are suitable catalysts for hydrogen production.