Heterogeneous and Nanostructured Electrocatalysts

There is considerable interest in development of solar fuels devices based on nanoscaled photovoltaic devices, integrated with electrocatalysts that utilize oxidizing equivalents, at a minimum overpotential, for the splitting of water to protons and O2 (oxygen evolution reaction, OER). Reducing equivalents (electrons) generated by the photovoltaic are concomitantly used to reduce the protons to hydrogen, again with a negligible overpotential.

Recent Projects

In collaboration with Alex Bell in Chemical Engineering, an investigation of electrocatalytic Co3O4 nanoparticles for water oxidation demonstrated increasing electrocatalytic activity as the particle size decreases.1 Additionally, 10 nm nanoparticles of Co3O4, CoO, and Co metal were found to exhibit small differences in performance, and each appears to access the same surface-active species under the catalytic conditions.2 The thermal molecular precursor (TMP) approach was used to prepare nanoparticles of cobalt metaphosphate, Co(PO3)2, for construction of nanostructured anodes for OER. This OER catalyst operates at an onset overpotential (310 mV; pH 6.4), that is substantially lower than that associated with Co3O4 and CoPi, two well-known cobalt-based catalysts for this reaction.3 Various surface-bound cobalt species, obtained by treatment of silica with Co[N(SiMe3)2]2, ranged from single-atom cobalt centers to small clusters, and interestingly the greatest activity was observed for the sample dominated by single-cobalt centers.4 Related studies probed the nature of the supporting oxides on cobalt catalysts for OER,5 and physical studies reveal mechanistic aspects to the function of surface species in OER.6