Abstract
Controlled tuning of material properties by external stimuli represents one of the major topics of current research in the field of functional materials. Electrochemically induced property tuning has recently emerged as a promising pathway in this direction making use of nanophase materials with a high fraction of electrode-electrolyte interfaces. The present letter reports on electrochemical property tuning of porous nanocrystalline Pt. Deeper insight into the underlying processes could be gained by means of a direct comparison of the charge-induced response of two different properties, namely electrical resistance and magnetic moment. For this purpose, four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the amount of deposited oxygen, is considered to be primarily caused by charge-carrier scattering processes at the metal–electrolyte interfaces. In comparison, the decrease of the magnetic moment upon positive charging appears to be governed by the electric field at the nanocrystallite–electrolyte interfaces due to spin–orbit coupling.
Highlights
Porous nanophase materials with electrochemically induced tunability of properties [1] have become a topic of growing research interest in the past few years
Four-point resistance measurements and SQUID magnetometry were performed under identical in situ electrochemical control focussing on the regime of electrooxidation
Based on tunability studies of the electrical resistance of porous nanocrystalline Pt [5] or nanoporous Pt [7] and of the magnetic moment of porous nanocrystalline Pd [10], the present work aims at a direct comparison of electrical resistance and magnetic moment with respect to in situ electrochemical oxidation by using porous nanocrystalline Pt as a model system
Summary
Porous nanophase materials with electrochemically induced tunability of properties [1] have become a topic of growing research interest in the past few years. Based on tunability studies of the electrical resistance of porous nanocrystalline Pt [5] or nanoporous Pt [7] and of the magnetic moment of porous nanocrystalline Pd [10], the present work aims at a direct comparison of electrical resistance and magnetic moment with respect to in situ electrochemical oxidation by using porous nanocrystalline Pt as a model system. These different electronic properties represent an ideal combination to provide a deeper understanding of the underlying charge-related processes since both properties are expected to respond differently on charging and chemical modification. The studies make use of a designed electrochemical cell that allows in situ magnetic studies in a SQUID magnetometer under electrochemical control [12]
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