Design of a Magnesium Microstructured Biohybrid Material for Practical Atmospheric CO₂ Mitigation

The rising levels of greenhouse gases such as CO₂ pose critical challenges for climate stability and indoor air quality. Here, we report the design and synthesis of a magnesium-based microstructured biohybrid (MicroMg) using a mild, enzyme-assisted process at room temperature and neutral pH. MicroMg consists of well-defined Mg₃(PO₄)₂ microstructures stabilized by a lipase scaffold, exhibiting high structural integrity and crystallinity. In aqueous media, MicroMg efficiently converts CO₂ into mainly bicarbonate under ambient conditions, achieving complete conversion of aqueous CO₂ within 30 min (TOF value of 16 h^-1) and demonstrating structural stability over repeated reactions. When this was incorporated into paint and applied to real wall surfaces, MicroMg effectively reduced CO₂ concentrations in gas-phase experiments, maintaining >90% of the initial activity over three washing cycles and performing better on larger coated areas (35 cm²) and with double-layer applications. Additionally, MicroMg remained active at elevated CO₂ concentrations (up to 1500 ppm), with a transformation rate of 16 ppm/h of CO₂ confirming its potential for mitigating indoor CO₂ levels. These results demonstrate that MicroMg is a sustainable, reusable, and scalable material for the CO₂ transformation, offering a promising strategy for both indoor air quality improvement and greenhouse gas mitigation.