Vertically Oriented Metallic Heterodimer Array Semiembedded in Flat Conductive Carbon Film for Electrochemical Application

Abstract

General synthesis of a highly oriented metallic heterodimer array based on a selective electrodeposition technique onto a metal nanoparticle-embedded carbon film is proposed, which enables the preparation of heterodimers with a wide variety of metal combinations. This method requires no surfactant, capping agent, organic solvent, or heat treatment. As a representative metal combination, a nickel (Ni)/palladium (Pd) heterodimer array was prepared by selective electrodeposition of Ni nanoparticles (Ni NPs) on top of partially exposed Pd NPs embedded in carbon film electrodes fabricated by a cosputtering technique. Such a selective electrodeposition becomes possible by utilizing the difference in electrodeposition overpotentials between carbon and Pd NP surfaces. X-ray photoelectron spectroscopy revealed a charge transfer from Ni NPs to Pd NPs, implying that the catalytic and optical properties can be expected to be controllable. The formed heterodimer array structure was mechanically stable against ultrasonication in ethanol for over 1 h because most parts of the Pd NPs were tightly embedded in the carbon film. After conversion from Ni to nickel hydroxide (Ni­(OH)2), the electrode showed high electrocatalytic activity toward glucose oxidation, with a higher turnover rate and lower overpotential compared to Ni­(OH)2 electrodeposited on pure carbon film electrodes.

Sputter Deposited Nanocarbon Film Electrodes for Electrochemical Analysis of Biomolecules

“…69,[74][75][76] We developed a simple process for fabricating a vertically oriented metallic heterodimer array embedded in flat carbon film by utilizing co-sputtering and electrodeposition. 77…”

“…Using this process, we successfully prepared Ni(upper)/Pd(lower), Pt/Pd, Au/Pd, Ni/Au, Pt/Au and Pd/Au heterodimers on the carbon film since the deposition potential of each metal is 0.08 to 0.37 V higher than that of carbon. 77 We can deposit the second metal nanoparticles by selecting a potential between the deposition onset potentials of metal and carbon surfaces.…”

“…In fact, a decrease in the onset potential (about 0.113 V) of glucose oxidation and a peak current increase were observed at the carbon film modified with Ni/Pd heterodimer compared with the carbon film modified with Ni nanoparticles. 77 We developed a much simpler system to improve the electrocatalytic performance of Ni nanoparticles by modifying the carbon film surface. Figure 11 78 At both pH values, the oxidation currents for N-carbon film modified with Ni nanoparticles are significantly higher than those for pure carbon film modified with Ni nanoparticles thanks to the improved turnover of Ni(OH) 2 .…”