Mechanism of Electroless Copper Deposition from [Cu(II)EDTA](2-)Complexes Using Aldehyde-Based Reductants

摘要

In this article, we present a mechanism for electroless copper deposition from alkaline solutions containing [Cu(II)EDTA]((aq))(2) and hydrolyzed aldehydes. The mechanism is based on quantum chemical calculations of the activation energies and reversible electron-transfer potentials. Low-coordinated, electroless-deposited surface Cu atoms are found to activate H abstraction from the CH bond of the aldehyde group, putting H on the surface and releasing a highly reducing electron in the process; this electron reduces [Cu(II)EDTA]((aq))(2) to [Cu(I)EDTA]((aq))(3). [Cu(I)EDTA]((aq))(3) is subsequently reduced to Cu-(ads)(0) by a second electron generated by the same process, releasing EDTA((aq))(4). Calculated reversible potentials for the reduction steps aid in interpretation of the catalytic behavior observed in experimental polarization curves.