Floating conductive catalytic nano-rafts at soft interfaces for hydrogen evolution

Abstract

Mo₂C nanowires and composites of Mo₂C nanoparticles formed on multiwalled carbon nanotubes (Mo₂C/CNT) were developed as advanced catalysts for hydrogen evolution at a polarised water–1,2-dichloroethane interface. Each catalyst acts as a catalytic nano-raft suspended at the interface to markedly enhance the rates of biphasic proton reduction in the presence of an organic solubilised electron donor, decamethylferrocene. Mo₂C nanoparticles were grown in situ on the conductive CNT support, achieving a high dispersion and intimate contact, thereby facilitating electron transfer between the components. The high catalytic activity of each catalyst was successfully demonstrated by their respective impacts on the reaction kinetics. The reaction rate increased more than 1000 times when the Mo₂C/CNT composite was present at a very low concentration of 25 μM. CNTs have the ability to act as highly efficient conduits or “transport superhighways” for injected electrons to reach the catalytic sites of the nanoparticle. Electrochemical instabilities, similar to those observed for the transfer of surface-active ions, were observed under experimental conditions that produced an abundance of hydrogen at the interface. Finally, the movement of CNTs floating at the interface under the influence of a cycling applied interfacial Galvani potential difference was vividly captured in a short movie.