Correction to: Nature Materials, published online 13 July 2020.

In the version of the Supplementary information in this article initially published, the catalyst synthesis of FeNC on page 3 was incorrect. The synthesis of FeNC involved 6.05 g FeCl36H2O, instead of 2.43 g FeCl3. The changes have been made to Supplementary information file available in the HTML version of the article.