1. Department of Chemistry Tsinghua University Beijing 100084 P. R. China
2. Applied Mechanics Laboratory Department of Engineering Mechanics and Center for Nano and Micro Mechanics Tsinghua University Beijing 100084 P. R. China
3. State Key Laboratory of Tribology and Key Laboratory for Advanced Materials Processing Technology Department of Mechanical Engineering Tsinghua University Beijing 100084 P. R. China
4. Department of Materials and Environmental Chemistry Stockholm University Stockholm SE‐106 91 Sweden