www.chemcatchem.org Accepted Article A Journal of Title: Stabilizing Co4+ Ions in Ultrathin Cobalt Oxide Nanosheets for Efficient Oxygen Evolution Reaction Authors: Jianghao Wang, Liping Li, Jing Li, Lingshen Meng, Chenglin Xue, and Guangshe Li This manuscript has been accepted after peer review and appears as an Accepted Article online prior to editing, proofing, and formal publication of the final Version of Record (VoR). This work is currently citable by using the Digital Object Identifier (DOI) given below. The VoR will be published online in Early View as soon as possible and may be different to this Accepted Article as a result of editing. Readers should obtain the VoR from the journal website shown below when it is published to ensure accuracy of information. The authors are responsible for the content of this Accepted Article. To be cited as: ChemCatChem 10.1002/cctc.201801253 Link to VoR: http://dx.doi.org/10.1002/cctc.201801253