The electrostatic control of metal complex adsorption might also be achieved at the
nanoscale over surfaces containing two oxides: The SEA method can be extended
to provide a simple, scientific method to prepare a wide range of bimetallic catalysts
and promoted catalysts. The idea is illustrated in Figure 13.13 in the simulation of
surface potential versus pH for a surface consisting of an oxidized carbon support,
with a PZC of 4, which supports particles of cobalt oxide, which has a PZC of about
9. At a pH of 6, the cobalt oxide phase will be protonated and positively charged,
whereas the carbon surface will be deprotonated and negatively charged. Hexachloroplatinate
anions should then be adsorbed selectively onto the cobalt oxide particles.
Subsequent reduction in H2 will be used to form the bimetallic PtCo particles. If the
composite surface was instead low PZC niobia (as supported promoter) and high
PZC alumina, PTA could be used for selective adsorption onto the niobia phase.