Electroactivity of nanoporous platinum depending on the porosity and potential for various electrode reactions

• Facile synthesis of nanoporous Pt (npPt) films with two different pore sizes
• Local porosity effect of npPt on reactions with various electrode reaction kinetics
• Electrocatalytic activity depending on the pore size of npPt
• Smaller pore is more efficient for catalyzing slower electrode reactions.

Electroactivity of nanoporous Pt (npPt) depending on the pore characteristics was studied for various electrode reactions having a range of electrode reaction kinetics: ferrocene oxidation, l-ascorbic acid (AA) oxidation, oxygen reduction reaction (ORR), H2O2 reduction, and glucose oxidation. npPts with two different degrees of the porosities (npPt-1 and npPt-2) were electrodeposited on recessed Pt microdisk electrodes (100-μm diameter), employing deposition solutions in which the composition ratios of Pt precursor, Triton X-100, and lead acetate were varied. npPt-1 has smaller microscale pores than npPt-2. The electroactivities of npPts were analyzed using amperometric sensitivities at mass-transfer-controlled and kinetic-controlled potential regions. Both npPt-1 and npPt-2 increased the sensitivities for all the reactions but reversible ferrocene oxidation remarkably compared to bare Pt. In the kinetic-controlled region, npPt-1 showed more greatly enhanced sensitivity compared to npPt-2 due to the smaller pores exerting more efficient confinement of a reactant near the Pt surface. In mass-transfer controlled region, npPt-2 was beneficial for relatively fast reactions (AA oxidation, ORR); while npPt-1 was advantageous for slower reactions (H2O2 reduction, glucose oxidation). This suggests that the particle-to-particle distance of the npPt affects the electroactivity and an optimum degree of the porosity is different depending on the reaction kinetics.

Figure optionsDownload as PowerPoint slide