Dealloyed ternary Cu@Pt-Ru core-shell electrocatalysts supported on carbon paper for methanol electrooxidation catalytic activity

Dealloyed ternary Cu@Pt-Ru core-shell electrocatalysts supported on carbon paper (CP) are fabricated by cyclic-co-electrodeposition and selective copper dealloying (CCED-SCuD). The physical properties of this catalyst such as surface and bulk compositions, electronic structure modification, phase structure, crystallite size, compressive lattice strain, and morphology were characterized by X-ray photoemission (XPS), inductive-coupling plasma atomic spectroscopy (ICP-AES), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscope, and transmission electron microscope (TEM). The best catalyst is Cu@Pt-Ru/CP, having core-shell structure with a Cu rich core and a Pt-Ru rich shell with grain size around 100 nm. Cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) reveal that ternary Cu@Pt-Ru/CP gives significantly low onset potential and high activity towards methanol electrooxidation reaction (MOR), achieving specific peak current at 265 mA.mg_Pt⁻¹, which is significantly higher than that of dealloyed binary Cu@Pt/CP (211 mA.mg_Pt⁻¹) and pure Pt/CP (170 mA.mg_Pt⁻¹). The highest current stability is found for the ternary Cu@Pt-Ru/CP with decay rate at 2.3 × 10⁻³ mA.mg_Pt⁻¹.s⁻¹. The enhancements of both activity and stability of the Cu@Pt-Ru/CP from the higher electrochemical surface area (ECSA) are major reason, which originates from the higher exposed surface of Pt, while the higher compressive lattice strain, electronic structure modification, and bi-functional mechanism are minor reason. However, the lower current density (J_P) of the ternary Cu@Pt-Ru/CP suggests lower intrinsic reactivity.