A Facile Route to Cotton-Like BiOCl Nanomaterial with Enhanced Dye-Sensitized Visible Light Photocatalytic Efficiency *Supported by the International Science and Technology Cooperation Program of China under Grant No 2014DFA60150, the National Natural Science Foundation of China under Grant Nos 51172113 and 51373086, and the Taishan Scholar Overseas Distinguished Professorship Program from the Shandong Provincial Government. (September 2015)