In the present paper, we have developed for the first time the electrochemically shape-controlled synthesis in deep eutectic solvents (DESs) for the preparation of Pt nanocrystals enclosed by high-index facets. Monodispersed concave tetrahexahedral Pt nanocrystals (THH Pt NCs) have been prepared through this new route. The concave THH Pt NCs were characterized by SEM, TEM, and AFM. The as-prepared concave Pt NCs are bounded with {910} and vicinal high-index facets, which exhibit superior catalytic activity and stability to those of the commercial Pt black catalyst for ethanol electrooxidation. We have demonstrated also that the electrochemically shape-controlled synthesis in DESs proves advantageous in controlling the size and shape of Pt NCs without the addition of seeds, surfactants, or other chemicals and could be applied in the synthesis of other noble metal NCs with high surface energy and high catalytic activity.

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Pt triambic icosahedral nanocrystals (TIH NCs) enclosed by {771} high-index facets were successfully synthesized electrochemically, for the first time, in ChCl-urea based deep eutectic solvents, and exhibited higher electrocatalytic activity and stability towards ethanol electrooxidation than a commercial Pt black catalyst.

Concave-disdyakis triacontahedral palladium nanocrystals (C-DTH Pd NCs) bound with 120 {631} high-index facets were prepared by electrochemically shape-controlled method in deep eutectic solvent (DES). It has found that both the adsorption of urea derived from EDS and the upper (E U ) and lower (E L ) limit potentials of the square-wave potential applied in the synthesis are contributed synergetically in controlling the shape of Pd NCs. The formation of C-DTH Pd NCs with well-defined shape was achieved by the dynamic interaction between urea adsorption at E U and growth at E L . In-situ FTIR spectroscopic studies revealed that the urea adsorbates at E U play a crucial role in shape evolution, especially in the formation of C-DTH Pd NCs. It has demonstrated that the as-synthesized C-DTH Pd NCs enclosed by {631} high-index facets exhibit higher electrocatalytic activity than Pd NCs with other shapes bound by {111} low-index facets (octahedral (OH) and icosahedral (IH)) towards ethanol electrooxidation in alkaline medium.