Fabrication of different copper nanostructures on indium-tin-oxide electrodes: shape dependent electrocatalytic activity

Abstract

This paper describes the fabrication of cubic, spherical, dendritic and prickly copper nanostructures (CuNS) on indium-tin-oxide (ITO) substrates by electrodeposition and their electrocatalytic activity towards the oxidation of glucose and hydrazine. CuNS with different shapes were fabricated on ITO substrates by using different applied potentials of +0.10, −0.10, −0.30 and −0.50 V for 400 s in the presence of 10 mM CuSO 4 and 0.1 M H 2 SO 4 . The formed CuNS were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), X-ray photoelectron spectroscopy (XPS) and electrical impedance spectroscopy (EIS). SEM images showed that cubic, spherical, dendritic and prickly CuNS were formed at applied potentials of +0.10, −0.10, −0.30 and −0.50 V, respectively. XPS showed characteristic peaks at 935 and 955 eV corresponding to Cu(0). The dendritic CuNS modified electrode exhibits a higher heterogeneous electron transfer rate constant of 3.70 × 10 −7 cm s −1 and an electroactive area of 51.32 cm 2 when compared to other CuNS modified electrodes. Further, the electrocatalytic activity of the different shaped CuNS modified ITO electrodes was examined towards the oxidation of glucose and hydrazine. Interestingly, the dendritic CuNS modified ITO substrate dramatically enhanced the oxidation currents of both glucose and hydrazine and also shifted their oxidation potential towards less positive potential when compared to bare ITO and other CuNS modified ITO substrates. The formation of dendritic CuNS was optimized with respect to deposition time, anion and pH and was monitored by SEM. Based on the results, a plausible mechanism for dendritic CuNS formation was proposed.

Patterning Cu nanostructures tailored for CO2 reduction to electrooxidizable fuels and oxygen reduction in alkaline media

“…for the electroreduction of NO 3 À and H 2 O 2 . 18 Although CuNSs are unstable in acidic environments under anodic polarization or unbiased conditions, 19 their anodic treatment in alkaline solutions causes the formation of CuO x nanostructures exhibiting catalytic activity towards electrooxidation of various organic substances, such as L-tyrosine, 20 glucose, 21,22 hydrazine, 22 and water. 23,24 Even though there are a number of successful applications of noble metal (Pt and Pd) based nanocatalysts to electrochemical conversion of CO 2 , [25][26][27] copper is the most promising catalyst for the CO 2 RR yielding valuable, high energy density products such as hydrocarbons, [28][29][30][31] alcohols, 28,29,32 formic acid and other carbonyls.…”

“…This can be achieved by laser ablation of copper surfaces, 13,41 plasma etching, 19 dealloying, 30,31 electrochemical polishing, 53 thermal annealing, 54 or electrodeposition. 10,18,20,22,43,55,56 Gowthaman and John demonstrated that the applied substrate potential during Cu electrodeposition affects the geometry of the obtained deposit. They obtained cubic, spherical, dendritic and prickly CuNSs from the same solution.…”

“…They obtained cubic, spherical, dendritic and prickly CuNSs from the same solution. 22 Local electroless deposition of copper has been done by the Schmuki group on AFM-produced nanosized scratches on Si(111) surfaces covered with an organic monolayer. 49 The same group electrodeposited micropatterns of CuNSs on a similar surface modied with an electron beam.…”

Ultrasensitive and Selective Hydrazine Determination in Water Samples Using Ag–Cu Heterostructures-Grown Indium Tin Oxide Electrode via Environmentally Benign Methods

“…Hence, extensive attention has been given to the accurate determination of trace level HZ in various environmental samples in recent years. Even though spectrophotometry, chromatography, and chemiluminescence methods were successfully employed for the determination of HZ, electroanalytical methods have been frequently employed by plenty of researchers, because of their fast response, low cost, better detection limit, sensitivity and selectivity, wide linear range detection, and suitability in real sample analysis. − …”

“…Electrochemical oxidation of HZ is a slow and sluggish process and requires high overpotential at conventional electrodes. − Generally, it has been shown that the electrocatalytic activity of the noble-metal nanoparticles-modified electrodes (Ag, Au, Cu, Pt, and Pd) toward analytes was enhanced either by increases in the oxidation/reduction current or decreases in the onset potential. − Fortunately, the better sensing performance can be succeeded by the synergism of binary composition interfaces, mostly metal composites. − Recently, bimetallic nanostructured materials are widely studied, because of their ease in synthesis and surface functionalization, besides enhanced catalytic activity, selectivity, and stability, when compared to their counterparts. − ,− In particular, Cu–Ag bimetallic NPs are employed widely in the electronics industry, catalysis, sensors, and biological devices, because of high electrical conductivity and catalytic activity. − Moreover, Cu-AgNPs not only possess better electromigration resistance than pure Cu but also avoids the oxidation of Cu . In addition, the catalytic activity and stability of Cu–Ag NPs-modified electrode are enhanced because of the synergism of Ag–Cu while loading with Ag. − In this perspective, it is expected that Cu–Ag combination would enhance the sensitivity toward the detection of HZ, because of the synergism between individual Cu and Ag atoms.…”