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.