* E-mail: jennifer.ai@mail.ccnu.edu.cn (Zhihui Ai); zhanglz@mail.ccnu.edu.cn (Lizhi Zhang) Received February 10, 2017; published March 29, 2017. Project supported by the National Key Research and Development Program of China (2016YFA0203000), National Natural Science Foundation of China (Nos. 21425728, 21177048, 21173093, 21477044, 51472100), Self-Determined Research Funds of CCNU from the Colleges’ Basic Research and Operation of MOE (Nos. CCNU16A02029, CCNU16A04005), Excellent Doctorial Dissertation Cultivation Grant from Central China Normal University (2015YBZD024 and 2016YBZZ031). 项目受国家重点研发计划纳米科技专项(2016YFA0203000), 国家自然科学基金(Nos. 21425728, 21177048, 21173093, 21477044, 51472100), 中央高校 基本科研业务费专项资金(Nos. CCNU16A02029, CCNU16A04005), 华中师范大学优秀博士学位论文培育计划(2015YBZD024 & 2016YBZZ031)资助.