A method is described herein to immobilize dispersed unsupported high area Pt particles (ca. 30 m2 g−1) on the surface of a glassy carbon (GC) disk of a rotating Pt(ring)/GC(disk) electrode (RRDE) assembly, without the use of Nafion® or other additives, allowing electrochemical measurements to be performed under forced convection with only minimal losses of Pt from the surface. Diffusion limiting currents, I lim, and half-wave potentials for O2 reduction recorded with dispersed Pt/GC electrodes at the highest attainable loadings (ca. 8.3 equivalent Pt monolayers and rotation rates 400≤ω≤2500 rpm, were found to be differ only slightly from those observed with a bulk Pt RDE of the same cross sectional area, e.g. I lim(Pt) ca. 1.06I lim(Pt/GC), under otherwise identical conditions. In addition, this novel strategy enables in situ surface modification of dispersed Pt particles on the GC disk of the RRDE by ad-atoms and subsequent voltammetric and electrocatalytic characterization for a wide spectrum of redox reactions.