Abstract
As part of an effort to develop biomaterials for the capture of CO
2
catalyzed by a carbonic anhydrase enzyme, the effects of an aqueous CO
2
saturated solution and a carbonic anhydrase on the gelation and texture of SiO
2
gels derived from tetramethoxysilane (TMOS), were studied. Both aqueous CO
2
and the enzyme were found to accelerate the gelation of silica, with a stronger effect when both the enzyme and CO
2
saturated aqueous water, were used. According to the gel texture data, aqueous CO
2
acted as an acid type catalyst, while the carbonic anhydrase acted as a weak base type catalyst. Moreover, a gel with a more granular visual aspect was obtained when both the enzyme and CO
2
saturated water were used. The latter characteristic was consistent with a double action of the enzyme, first as a gelation catalyst on the silica precursor, secondly as a reverse protonation catalyst which accelerated the back nucleation of CO
2
gas bubbles from aqueous HCO
3
−
anions.