1. Collaborative Innovation Center for Nanomaterials & Devices, College of Physics, Qingdao University 1 , Qingdao 266071, China
2. Center for Nanotechnology & Sustainability, Department of Mechanical Engineering, College of Design and Engineering, National University of Singapore 2 , Singapore 117576
3. State Key Laboratory of Bio-Fibers & Eco-Textiles, Qingdao University 3 , Qingdao 266071, China