Facile control of surface crystallographic orientation of anodized nanoporous gold catalyst and its application for highly efficient hydrogen evolution reaction

Mie, Yasuhiro; Hirano, Yu

doi:10.1016/j.jcat.2020.06.023

Cited by 17 publications

(28 citation statements)

References 54 publications

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“…Previously, we reported that NPG electrodes prepared from solutions of 35 and 500 mM HCl (NPG-35 and NPG-500) exhibit different contributions of surface atomic structure and crystallographic orientation [ 30 ]. The NPG-35 and NPG-500 electrodes were enriched in the Au(111) and Au(100) orientations, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…In general, an NPG structure cannot form a monolithic surface orientation because it lacks high-index facets and surface steps/kinks that maintain the curvature of its three-dimensional bicontinuous porosity [ 35 ]. NPG structures with different contributions of low-index facets have been prepared by the anodization method described above [ 30 ] and other dealloying methods [ 35 ]. Thus, the multipeaks observed in the voltammograms of glucose oxidation at NPG-35 and NPG-500 are reasonable.…”

Section: Resultsmentioning

confidence: 99%

“…NPG was prepared by simply applying an anodization potential as previously reported [ 30 ]. A gold disk electrode (ø = 3 mm) was polished with 1.0 and 0.125 μm of diamond slurries followed by a 0.05 μm of alumina slurry until a clear mirrorlike surface was obtained.…”

Section: Methodsmentioning

confidence: 99%

“…The gold surface had been passivated by the formation of an oxide layer, as indicated by a sudden current drop [ 30 , 31 , 32 ]. Referring to the literature, the anodization potential for NPG construction was determined as 10–40 mV more negative than the passivation potential [ 30 , 31 , 32 ]. The morphology of the NPG surface was characterized by scanning electron microscopy (SEM) (S-4300 FE-SEM, Hitachi Ltd., Tokyo, Japan).…”

Section: Methodsmentioning

confidence: 99%

“…However, the effect of the surface orientation in the NPG structure on electrochemical saccharide oxidation has not been discussed. Fairly recently, we reported a facile method able to control the composition of the surface crystallographic orientations of NPG catalysts [ 30 ].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Oxidation of Monosaccharides at Nanoporous Gold with Controlled Atomic Surface Orientation and Non-Enzymatic Galactose Sensing

Mie

Katagai

Ikegami

2020

Sensors

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Non-enzymatic saccharide sensors are of great interest in diagnostics, but their non-selectivity limits their practical diagnostic abilities. In this study, we investigated the electrochemical oxidation of monosaccharides at nanoporous gold (NPG) catalysts with different contributions of surface crystallographic orientations. Fructose elicited no clear electrochemical response, but glucose, galactose, and mannose produced clear oxidative current. The onset potentials for oxidation of these saccharides depended on the surface atomic structure of the NPG. The oxidation potential was approximately 100 mV less positive at the Au(100)-enhanced NPG than at the Au(111)-enhanced NPG. Furthermore, the voltammetric responses significantly differed among the saccharides. Galactose was oxidized at less positive potential and exhibited a higher current response than the other saccharides. This tendency was enhanced in the presence of chloride ions. These features enabled the selective and sensitive detection of galactose at an NPG electrode without enzymes under physiological conditions. A linear range of 10 μM to 1.8 mM was obtained in the calibration plot, which was comparable to those in previously reported enzymatic galactose sensors. Thus, we demonstrated that controlling the crystallographic orientation on the nanostructured electrode surface is useful in developing electrochemical sensors.

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Section: Resultsmentioning

confidence: 99%