1. State Key Joint Laboratory of Environment Simulation and Pollution Control; School of Environment; Tsinghua University; Beijing 100084 China
2. Particles and Catalysis Research Group, School of Chemical Engineering; The University of New South Wales; Sydney NSW 2052 Australia
3. Key Laboratory of Beijing on Regional Air Pollution Control; Beijing Key Laboratory for Green Catalysis and Separation and Laboratory of Catalysis Chemistry and Nanoscience; Department of Chemistry and Chemical Engineering; College of Environmental and Energy Engineering; Beijing University of Technology; Beijing 100124 China
4. National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering; The State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Advanced Materials (MOE); Tsinghua University; Beijing 100084 China