Inorganic–Organic Hybrid Modified Calcium Peroxide Used as Controllable Oxygen-Releasing Compound

To address the uncontrollable oxygen-release performance of conventional oxygen-releasing compounds (ORCs), a novel calcium peroxide (CaO₂)-based ORC was developed through synergistic inorganic-organic modification using a silica (SiO₂) coating and octyltriethoxysilane (OTES) grafting. A sol-gel method via tetraethyl orthosilicate (TEOS) hydrolysis-condensation was employed to construct nano SiO₂ layers on both internal and external surfaces of CaO₂ particles, followed by chemical grafting of OTES onto Brønsted acid sites of SiO₂ to form a hydrophobic thin organic layer, resulting in core-shell structured composites. Characterization revealed that the SiO₂ layer chemically bonded with CaO₂ through Ca-O-Si linkages, while OTES anchored onto SiO₂ via Si-O-Si covalent bonds, establishing a dual chemically bonded controlled-release barrier. The modified OTES-SiO₂@CaO₂ exhibited significantly tunable hydrophobicity, with water contact angle ranging from 29.4° to 145.2°, effectively controlling water infiltration and subsequent CaO₂ hydrolysis. Oxygen-releasing performance tests demonstrated a 53.3% reduction in cumulative oxygen release over 35 days compared to raw CaO₂, with release rates precisely tunable by adjusting OTES grafting density. Release period of the developed inorganic-organic hybrid modified CaO₂ composites ranged from 387 to 790 days estimated by the release kinetics data, exhibiting a significantly better controlled-release performance with lower coating content and longer release period compared to the reported work. This hybrid modification strategy provides a theoretical foundation for the rational design of functional controlled-release materials in environmental and chemical applications.