Electrochemical studies on layered perovskite lead niobates, RbPb2Nb3O10 and HPb2Nb3O10, were carried out. Mott-Schottky plot analysis suggests these materials are n-type semiconductors; the flatband potentials (pH 0) of RbPb2Nb3O10, HPb2Nb3O10, and Pt/loaded HPb2Nb3O10 (with Pt(NH3)42+, denoted Ptin/HPb2Nb3O10) are estimated to be -0.14, -0.08, and 0.07 V us. SCE, respectively, and shifted negatively by ca. 60 mV per pH unit. Electrochemical probing with Fe(CN)63-/4-, Ru(NH3)63+/2+ and MV2+/+/0 not only confirms these results but suggests proton reduction is much favored at HPb2Nb3O10 over RbPb2Nb3O10. This proton reduction is significantly facilitated by the internal platinum loadings (with Pt(NH3)42+); however, external platinization with PtCl62- does not give a similar catalytic effect. Admittance analysis suggests midgap states are populated in the interior of HPb2Nb3O10. With these inner surface states, electron transfer is greatly eased and a favorable proton reduction results at the HPb2Nb3O10 particles.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry