Direct CO 2 capture by alkali-dissolved cellulose and sequestration in building materials and artificial reef structures.

Current carbon capture and utilization (CCU) technologies require high energy input and costly catalysts. Here, we offer an effective pathway that addresses climate action by atmospheric CO 2 sequestration. Industrially relevant highly reactive alkali cellulose solutions are used as CO 2 absorption media. The latter lead to mineralized cellulose materials (MCM) at a tailorable cellulose-to-mineral ratio, forming organic-inorganic viscous systems (viscosity from 10 2 to 10 7 mPa s and storage modulus from 10 to 10 5 Pa). CO 2 absorption and conversion into calcium carbonate and associated minerals translate to maximum absorption of 6.5 gCO 2 g cellulose -1 , tracking inversely with cellulose loading. Cellulose lean gels are easily converted into dry powders, shown as a functional component of ceramic glazes and cementitious composites. Meanwhile, cellulose-rich gels are moldable and extrudable, yielding stone-like structures tested as artificial substrates for coral reef restoration. Life Cycle Assessment (LCA) suggests new CCU opportunities for building materials, as demonstrated in underwater deployment for coral reef ecosystem restoration. This article is protected by copyright. All rights reserved.