Correction to: Nature Catalysis https://doi.org/10.1038/s41929-019-0334-3, published online 16 September 2019.

In the version of this Article originally published, the Fig. 3 panels were mislabelled and the mean particle size in Fig. 3e, which is now labelled Fig. 3b, was incorrectly given as ‘1.2 nm’. From left to right, the top row of panels should have been labelled a, c, e and g and the bottom row of panels should have been labelled b, d, f and h. The mean particle size in Fig. 3b should have been ‘1.0 nm’. This has been corrected in the online versions of this Article.