We attribute this to the poor stability of Vo defects or reduced Zn in ZnO under air exposure. The adsorption energy of CO2 at an oxygen vacancy on the ZnO surface, been calculated to be -0.60 eV. This is less favorable than the adsorption of CO2 onto an oxygen vacancy in TiO2, whose energy ranges from -2.53 eV to -0.98 eV depending on the location of the vacancy and the orientation of CO2. The formation energy difference suggests that ZnO would be expected to have a greater number of oxygen vacancies present on its surface compared to TiO2, particularly as the rate of the vacancy formation is increasing with input power. However, those vacancies would not be as capable of forming a bound CO2 ALD-ZnO and ALD-Al2O3 have been shown to have small but significant power dependent activities that can influence conversions beyond only support-catalyst interactions and plasma enhancement effects. The ALD synthesis method described here can be used in conjunction with other techniques, such as surface specific spectroscopy and more advanced reactor output product analysis to more fully characterize the contribution of a support material to the overall plasma-catalytic activity of a support-catalyst system. Care should be taken to not underestimate the activity of the support and experiments should be designed as to ensure the activity of the support controlled when comparing multiple catalysts across wide input power ranges.