Retraction statement

The Royal Society of Chemistry hereby wholly retracts this Journal of Materials Chemistry A article, with the agreement of the authors, due to concerns with the reliability of the electron microscope (EM) images in the published article. The HR-STEM image in Fig. S4 and the STEM images in Fig. 1a, S1, S3, S5, S6, S13, S14, S15 and S33 contain repetitions of distinct shapes or patterns within the images. The authors informed us that the characterisation was completed by a third party company and they used the images “without any editing or modification”. The authors repeated the experiments and requested to provide replacement data for Fig. 1a, S1, S3–S6, S13–S15 and S33. The new figures were reviewed by an independent expert. The authors believe that the scientific content and conclusions of the related studies presented by the pictures in the published paper can be reproduced. However, the independent expert still questions the reliability of the published images. The authors informed us that due to a flooding accident in the laboratory, the original data of the published EM images were destroyed. In addition, the third party company only saved the test data for one month. Due to the large number of images, it is not possible to replace the published images with the new figures. To avoid the possibility of publishing unreliable EM images, the authors agree to retract this paper to protect the rigor of the scientific record.