Fabrication and properties of silicene and silicene–graphene layered structures on Ir (111)*Project supported by the National Basic Research Program of China (Grant Nos. 2013CBA01600 and 2011CB932700), the National Natural Science Foundation of China (Grant Nos. 61222112, 61390501, 51325204, 11334006, and 61306114), the Science Fund from Chinese Academy of Sciences (Grant Nos. 1731300500015 and XDB07030100), and the Fundamental Research Funds for the Central Universities, China. (August 2015)