This article presents a comparative study of the deposition behaviors of Pt and PtBi nanoparticles on glassy carbon. Sea-urchin-like Pt nanoparticles and spherical PtBi nanoparticles were produced by potentiostatic deposition. Chronoamperometric characterizations show that the Pt electrodeposition corresponds to the mechanism for 3D progressive nucleation and growth. The sea-urchin-like morphology can be attributed to the effect of applied potential and the electroadsorption of hydrogen and trace Cl^-. The PtBi electrodeposition fits well to the mechanism for 2D progressive nucleation at t/tmax 〈 1.5, and there is a transition from 2D adlayer to 3D clusters at t/tmax 〉 1.5. The spherical PtBi nanoparticles result from the three effects caused by bismuth co-electrodeposition： higher overpoten-tial, strengthened affinity to Cl^-, and improved hydrogen evolution. These results suggest that the adsorption of solution anions and cations on the deposit surface can be used to change the morphologies of the deposits.
