1. State Key Laboratory of Electrical Insulation and Power Equipment and Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an Shaanxi 710054 China
2. School of Chemistry Xi'an Jiaotong University Xi'an Shaanxi 710049 China
3. School of Material Science and Engineering PCFM Lab Sun Yat‐sen University Guangzhou Guangdong 510275 China
4. Deutsches Elektronen‐Synchrotron (DESY) Notkestr. 85 D‐22607 Hamburg Germany