PhD student Yang Liu published a paper in Journal of the American Chemical Society

Yang Liu is a fifth year Ph.D. student from Dr. Swihart’s group. His research interests are in the general area of synthetic inorganic nanochemistry. Colloidal metal chalcogenide nanocrystals have captured the attention of many researchers because of their potential for use in thermoelectric, electrocatalytic, and photovoltaic applications. Cation exchange is a central strategy for post-synthesis modification of nanocrystals, and can provide a predictable means to design crystalline nanostructures with controlled size, shape, and composition. 

Yang’s recent work showed for the first time that biconcave (red blood cell shaped) nanoplatelets can be produced via cation exchange reactions. This study not only provides a better understanding of the relationships among composition, morphology and crystal structure for copper sulfide-based nanocrystals, but also provides a pathway to a previously inaccessible nanostructure.

Briefly, djurleite Cu_1.94S nanoplatelets with a novel biconcave shape were produced using copper indium sulfide nanoplatelets as a template. The unique biconcave structures form through the assembly and migration of defects in the nanoplatelets. These defects are generated by rapid out-diffusion of In³⁺ ions faster than they can be replaced by Cu⁺ ions. The study also showed that this approach to synthesis of biconcave nanoplatelets can be applied to different stoichiometric and crystal systems of ternary nanoplatelets. As an extension of the published study, Yang is now synthesizing biconcave nanoplatelets of other materials through cation exchange to further replace the Cu⁺ ions in the Cu_1.94S biconcave nanoplatelets. The resulting biconcave metal sulfide (e.g. PbS, MnS, or MoS₂) nanostructures could have even broader potential for use in solution-processed photovoltaics, electrocatalysis, and photocatalysis. These studies can provide further inspiration and fundamental insights for design and synthesis of novel copper sulfide-based nanostructures. This discovery was recently published in the Journal of The American Chemical Society (JACS).

Yang is expecting to graduate in summer 2018 and plans to continue his research career as a postdoctoral fellow in the general field of synthetic inorganic nanochemistry with applications in areas such as catalysis, photonics, and energy conversion and storage.