Fig. 2b shows that the particle size rises first and then aggregation
(A5 in Table 3) is formed with the increment of NH3 concentration.
This result is inconsistent with that of Wang et al. [18].
NH3, as a catalyst, could accelerate TEOS hydrolysis and condensation
reactions, resulting in producing more oligomers to form larger
particles, but at higher NH3 concentration, aggregation will
be formed if condensation rate is larger than TEOS hydrolysis rate.
Fig. 2c illustrates that the influence of the water concentration on
particle size follows the similar trend as NH3, that is, the particle
size increases with increasing H2O concentration and reaches the
maximum value at about 6 M, and then descends at higher concentration.
This result shows good agreement with the work of
[16,18,19]. H2O could accelerate TEOS hydrolysis to contribute to
formation of larger particles, while at higher H2O concentration,
H2O dilutes the oligomers in reaction solution, resulting in the formation of smaller particles.
Fig. 2b shows that the particle size rises first and then aggregation(A5 in Table 3) is formed with the increment of NH3 concentration.This result is inconsistent with that of Wang et al. [18].NH3, as a catalyst, could accelerate TEOS hydrolysis and condensationreactions, resulting in producing more oligomers to form largerparticles, but at higher NH3 concentration, aggregation willbe formed if condensation rate is larger than TEOS hydrolysis rate.Fig. 2c illustrates that the influence of the water concentration onparticle size follows the similar trend as NH3, that is, the particlesize increases with increasing H2O concentration and reaches themaximum value at about 6 M, and then descends at higher concentration.This result shows good agreement with the work of[16,18,19]. H2O could accelerate TEOS hydrolysis to contribute toformation of larger particles, while at higher H2O concentration,H2O dilutes the oligomers in reaction solution, resulting in the formation of smaller particles.
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