Surface plasmon-enhanced activity and stability for methanol oxidation on gold caviar-like assembly under solar light

The surface plasmon-enhanced catalytic performance of a gold caviar-like assembly (Au-CA) in methanol electrooxidation was investigated with and without simulated solar irradiation. An Au-CA catalyst synthesized by an ion sputtering method not only exhibited an excellent anodic peak current density (115.86 mu A mu g(-1)) but also displayed long-term catalytic stability for methanol electrooxidation. The AuCA catalyst also provided an anodic peak current density of 248.9 mu A mu g(-1) for methanol electrooxidation under simulated solar irradiation. This value corresponded to a 2.15-fold increase with respect to that in the absence of solar light irradiation in a deoxygenated solution of 1.0 M KOH and 1.5 M CH3OH. The diffuse reflectance UV-vis absorption spectra and photoelectric response performance of the as-prepared Au-CA catalyst were investigated to understand the effectiveness of the surface plasmon resonance of Au nanoparticles for the enhancement of methanol electrooxidation performance. The results showed that the Au-CA catalyst exhibited a broad absorption peak at a wavelength of 515 nm with a red shift in comparison with that of a solution of Au nanoparticles. The photocurrent density of the Au-CA catalyst was 175.8 mu A mu g(-1) at an irradiation wavelength of 468 nm, which was 2.5 times higher than that at 640 nm (70.2 mu A mu g(-1)) in a deoxygenated solution of 0.5 M Na2SO4. These findings suggested the potential of the new strategy for the improvement of the activity and durability of Au in methanol electrooxidation in direct methanol fuel cell technologies.