Hot-Injection Synthesis of PtCu3 Concave Nanocubes with High-Index Facets for Electrocatalytic Oxidation of Methanol and Formic Acid

Extensive efforts have been devoted to tailoring the composition and shape of Pt nanomaterials for a high catalytic property. Herein, we report facile hot-injection synthesis of PtCu3 concave nanocubes enclosed by high-index facets of {720}, {520}, and {320}. Cetyltrimethylammonium bromide (CTAB) and trinoctylphospine oxide (TOPO), as the structural-directing agents, play indispensable roles in the formation of concave nanocubes of PtCu3. The introduction of Br from CTAB facilitates the galvanic replacement reaction on the {100} facets, which lead to formation of the concave structure; TOPO is essential to achieve the uniform cubic structure. The PtCu3 concave nanocubes exhibit mass activity of 0.69 A mgPt–1 and specific activity of 2.44 mA cmPt–2 for methanol oxidation, which are 2.1 and 4.4 times higher than the commercial Pt/C, respectively; for formic acid oxidation they are 0.45 A mgPt–1 and 1.57 mA cmPt–2, and are 2.0 and 4.2 times higher than the commercial Pt/C, respectively. The PtCu3 concave nanocubes and commercial Pt/C show the same onset potentials for methanol oxidation, whereas the onset potential on the PtCu3 concave nanocubes for formic acid oxidation is negatively shifted by ca. 124 mV compared to that of the commercial Pt/C. It suggests that the PtCu3 concave nanocubes are more sensitive to the electrocatalytic oxidation of formic acid than methanol. This superior electrochemical performance will inspire more investigations into the rational design of high-performance Pt-based electrocatalysts.