摘要： Two-dimensional (2D) metal dichalcogenide nanomaterials have been receiving enormous research interest for electronic, optoelectronic, and catalytic applications. However, the facile tunability of alloying and doping, as well as the successful formation of ideal defect-free nanoplate morphology have been hardly achieved for 2D nanomaterials. Herein, we successfully synthesized a series of 2D solid-solution SnSxSe2(cid:1)x particles of 0.20–2.00 μm width and 30–68 nm thickness with morphological defect-free nanoplate via a solvothermal reaction. With controlled reactivities of elemental chalcogen precursors, a co-surfactant hexylamine together with a structure-directing agent polyvinylpyrrolidone was found to be essential for realizing ideal defect-free nanoplate morphology of SnSxSe2(cid:1)x particles without either cabbage-like or twinned structure. The successful synthesis of morphologically defect-free SnSxSe2(cid:1)x nanoplates with rationally controlled energy band gaps ranging from 1.36 eV for SnSe2 to 1.96 eV for SnS2 could provide promising materials for electronics, optoelectronics, and electrocatalytic applications.