Low temperature atomic layer deposition of PbO2for electrochemical applications.

Abstract

A low temperature atomic layer deposition (ALD) process for PbO₂was developed using bis(1-dimethylamino-2-methyl-2-propanolate)lead(II), Pb(DMAMP)₂, and O₃as the reactants, with a high growth rate of 2.6 Å/cycle. PbO₂readily reduces under low oxygen partial pressures at moderate temperatures making it challenging to deposit ALD PbO₂from Pb²⁺precursors. However, thin films deposited with this process showed small crystalline grains of α-PbO₂and β-PbO₂, without signs of reduced PbO_xphases. The ALD PbO₂thin films show the high electrical conductivity characteristic of bulk PbO₂. In situ measurements of ALD PbO₂film conductivity during growth suggest a reaction mechanism by which sub-surface oxygen mobility contributes to the growth of resistive PbO or PbO_xduring the Pb(DMAMP)₂surface reaction step, which is only fully oxidized from Pb²⁺to Pb⁴⁺during the O₃reaction step. These films were electrochemically reduced to PbSO₄in H₂SO₄and then reoxidized to PbO₂, demonstrating their suitability for use as an electrode material for fundamental battery research and other electrochemical applications.