Morphological Control of Carbon-Supported Pt-Based Nanoparticles via One-Step Synthesis

The morphology of Pt-based nanoparticles supported on carbon is controlled to enhance the oxygen reduction reaction (ORR) catalytic performance. Herein a simple one-step method without a polymer surfactant is demonstrated to synthesize Pt-Cu nanoclusters, Pt-Cu nanospheres, and Cu-doped Pt nanoplates. Metal precursors are reduced in a NaCl or NH4Cl aqueous solution containing carbon supports, and nanoparticles are directly deposited on carbon. Cl− ions generated from NaCl or NH4Cl behave as oxidative etchants when O2 is dissolved in the synthesis solution, delaying the reduction of metal ions and leading to larger particles. Nanoclusters are obtained in the absence of Cl− ions. In addition, NH4+ guides the growth direction of Pt in the presence of oxidative etchants, forming a plate-like morphology that exposes the {111} facets. Half-cell measurements are performed in acidic media to evaluate the electrochemical properties. Cu-doped Pt nanoplates exhibit a 3.67-times higher ORR catalytic activity than the commercial Pt catalysts thanks to the synergistic effect with a small amount of Cu and selective exposure of the {111} facets. The result suggests that transition metals in Pt-based electrocatalysts may be unnecessary to form intermetallic alloyed crystals for the enhanced ORR performance.