Catechism of the Catholic Church §296 — excerpt
We believe that God needs no pre-existent thing or any help in order to create, nor is creation any sort of necessary emanation from the divine substance.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: Dei Filius, cann. 2-4: DS 3022-3024 · Lateran Council IV (1215): DS 800 · DS 3025 · St. Theophilus of Antioch, Ad Autolycum II, 4: PG 6, 1052