Open access publishing can contribute to sustainability initiatives by making research around the topic open and free. Widening access is key to the development of research around the world and providing education for all.
There are well-known general portals such as Directory of Open Access Journals (DOAJ) and Directory of Open Access Books (DOAB) that have content relevant to sustainability. You can explore these general resources further on the Library's open access content page.
You will also find open access journal articles via resources such as Google Scholar