Topological Materials Database https://www.topologicalquantumchemistry.com/#/

Materials Project https://materialsproject.org/

2D Materials Encyclopedia http://2dmatpedia.org/

Materials Web. https://www.materialsweb.org/

Materials Cloud. https://www.materialscloud.org/home

Computational 2D materials database https://cmr.fysik.dtu.dk/c2db/c2db.html#c2db

ICSD via UTK Library: https://icsd-fiz-karlsruhe-de.proxy.lib.utk.edu/search/basic.xhtml;jsessionid=6370167292B6D53FCD62A24CE4B651BC

Springer Materials   https://materials-springer-com.proxy.lib.utk.edu/

FLOW for materials discovery: http://aflowlib.org/