Mesoporous silica nanosphere-based oxygen scavengers

Abstract

We synthesized mesoporous silica nanospheres (MSNs) with small particle size (under 100 nm) and large surface areas (>800 m2/g) by modified Stöber method. We investigated coating of oxygen adsorber materials (iron-based and titania-based) by atomic layer deposition on the prepared MSNs. We found that MSNs without any coating are capable of adsorbing oxygen by physisorption, and that due to their high surface areas they can outperform commercial oxygen scavengers for atmospheres with moderate and low humidity levels. Their performance is further enhanced for optimized thickness of FeOx or TiOx coating, where chemisorption contributes to oxygen scavenging process. To further investigate the oxygen adsorption on MSNs, samples with different annealing times were prepared and characterized, and the oxygen adsorption could be attributed to incomplete removal of silicon precursor residue. While the samples with prolonged annealing time do not exhibit oxygen adsorption, the high oxygen adsorption capacity can be restored by glucose treatment which results in carbon-based surface coating of MSNs. Due to their fast response and high oxygen adsorption capacity, the prepared materials are highly promising as oxygen scavengers, in particular for applications in dry environments where humidity activation is undesirable.