Direct control of defects in molybdenum oxide and understanding their high CO2 sorption performance

It is increasingly important to understand and study materials for removal of carbon dioxide (CO2) or other harmful gases for both industrial and commercial uses. In this work, we present pioneering work in studying how defects affect the sorption performance of molybdenum (Mo) oxide. Using a unique thin film approach, we are able to study the chemical states of the sorption material and we demonstrate how to directly influence and control the defect states of an electroplated Mo oxide. Subsequently, we show the high performance of the coated materials yielding CO2 sorption capacity of ∼23 mmol g−1 at 760 mmHg or an area capacity of 0.018 μmol mm−2. By using XPS, NAPXPS and sorption isotherms, supported by first-principles calculation of CO2 interaction with Mo defects, we report on the important role of Mo4+ defects that can increase the CO2 sorption performance by ∼50%.