Electrochemically Dealloyed Cu–Pt Nanostructures for Oxygen Reduction and Formic Acid Oxidation

Abstract

Surface engineering of catalysts by dealloying is a promising strategy to fine-tune the catalytic activity. Rational electrochemical surface engineering significantly improves the electrocatalytic performance. Herein, we demonstrate the synthesis of a surface-engineered CuxPty bimetallic electrocatalyst of low Pt content by solvothermal and subsequent electrochemical dealloying approaches for the electrocatalytic reduction of oxygen and oxidation of formic acid. The electrochemically dealloyed electrocatalysts have enhanced activity toward the oxygen reduction reaction and formic acid oxidation reaction (FAOR) due to the dealloying-induced increase in the electrochemically active surface area and lattice strain. Among the electrochemically dealloyed catalysts (Cu11Pt89, Cu17Pt83, and Cu23Pt77), Cu17Pt83 shows excellent ORR activity in acidic medium with an onset potential of 0.98 V. It delivers a limiting current density and mass specific activity of 5.4 mA/cm2 and 0.157 A/mgPt, respectively. The mass specific activity of Cu17Pt83 is 2–12 times higher than that of 20% Pt/C and monometallic Pt nanoparticles. The dealloying-induced lattice strain on Pt modifies the d-band structure. Such modification weakens the chemisorption of oxygenated species (OHads and OOHads) and improves the electron transfer kinetics. Among all dealloyed CuxPty catalysts, the low-Pt content Cu23Pt77 catalyst exhibits high FAOR activity. The Cu23Pt77 catalyst has good tolerance toward in situ generated CO, and the CO-stripping potential is significantly less positive compared to that of the other catalysts.