Are children's prayers more efficacious?

Are children's prayers more efficacious? It would seem so, because they are purer and more innocent. Matt 18:10 : >See that you despise not one of these little ones: for I say to you, that their angels in heaven always see the face of my Father who is in heaven. What did Fathers, Doctors of the Church, or other saintly Catholic theologians have to say about the efficacy of children's prayers?