Correction to: Nature Nanotechnology https://doi.org/10.1038/s41565-020-0657-x, published online 10 March 2020.

In the version of this Review Article originally published, ref. 68 (Zeng, X., Li, J. & Ren, Y.) should not have been included; it has now been deleted from the reference list and its citation removed from the text. Subsequent references have been renumbered. Furthermore, in the final sentence in Fig. 3 caption ref. 19 should have been the last in the list of references, as it relates to panel f. The online versions of the Review Article have been amended.