Neither persuasive techniques nor opinions belong in an informative text. Such a text is supposed to offer relatively neutral information, not to argue in favor of itself. Its model is the encyclopedia entry, which presents widely accepted knowledge. Opinions are the antithesis of such knowledge and, if persuasive techniques are needed, we are dealing with an unresolved or polemical subject that is not fit for a merely informative text. Even supporting evidence would be out of place, since using evidence usually means that you are arguing something. However, if a text wishes to explain a widely accepted scientific theory, for example, then the use of evidence could be justified.
On the other hand, an informative text can use a narrative (for example when recounting a historical event).
