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Abstract: Determination of the surface area of commercial carbon-black (CB) by cyclic-voltammetry (CV) measurements of the electrochemical double-layer charge (Q) in aqueous sulfuric acid was investigated. Various factors that affect the Q value associated with CB, including: the presence of redox-reversible function-groups, the binders used for the formation of thin-film CB electrodes, the scan rates of the CV measurement, H2SO4 electrolyte concentration and the volume of air contained in the pores of the CB samples were examined. Conditions for measuring Q without interference from these factors were investigated and the data derived, without interference, was found to correlate well with the surface area of the CB. The results show that the total Brunauer–Emmett–Teller (BET) surface area shows good correlation (R 2 =0.993) with the Q value corresponding to a full charge/discharge of the CB (Q 0), obtained by extrapolation at a zero scan rate; additionally, the CB micropore surface area (diameter<2nm) shows good linear correlation with the Q deficiency (Q 0–Q), measured at 5mVs−1 (R 2 =0.998). [Copyright &y& Elsevier]

The effect of defective graphene flake (DGF) as supports for Pd nanocubes (Pd NCs) in the catalysis of d-glucose oxidation reaction (GOR) was studied. The DGF used to support the Pd NCs were prepared via both a sonoelectrochemical method (DGFSECM) and a chemical reduction method (DGFCM). The comparable data supported by the diffraction electron pattern of transmission electron microscope (TEM) and X-ray diffraction (XRD) spectra evidence that the corners of the Pd NCs faced up toward the both DGF supports, leading to an increase in the XRD intensity of the Pd (111) peak. Additionally, a fair electrochemical comparison of the DGF support effect on GOR catalysis via Pd NCs in a NaOH electrolyte indicated that the DGFSECM-supported Pd NCs (Pd NC/DGFSECM) and DGFCM-supported Pd NCs (Pd NC/DGFCM) demonstrated earlier onset potentials and an overall order of Pd NC/DGFSECM> Pd NC/DGFCM> commercial Pd/C catalyst > Pd NCs for the peak charge accompanying the formation of glucolactone was obtained. Through the use of a DGFSECMsubstrate, the electrochemical surface area and charge transfer resistance toward GOR were significantly improved. In addition, as supported by the catalytic activity for GOR, Pd NC/DGFSECMshowed remarkable sensitivity and tolerance to foreign substances in the application as a non-enzymatic glucose sensor, where Pd NC/DGFSECMshowed higher two-period sensitivities of 74 and 45.86 μA·mM−1·cm−2for 0.25–5 and 5–24 mM d-glucose, respectively. The high recovery in serum sample analyses further confirmed the potential of Pd NC/DGFSECMas glucose sensors.

Pd nanocubes (∼10 nm) and Pd nanocubes coated with multi-armed Pt shells have been successfully prepared. Their microstructures are determined from their electron diffraction patterns and line scan energy-dispersive X-ray measurements taken on a single particle. These Pd nanocubes and the Pd-Pt nanocubes are applicable as catalysts for the alkaline oxygen reduction reaction. On the basis of the same loading mass of catalyst, the results of rotating ring-disk electrode measurements indicate that the cubic Pd nanoparticles and particles coated by multi-armed Pt shells display activities of 1.47 × 10−2and 9.22 × 10−3mA μg−1, respectively. These values are greater than the 6.79 × 10−3mA μg−1observed for Pt nanoparticles. The prepared Pd nanocubes and the Pd-Pt core-shell catalysts, as well as Pt nanoparticles, show 98% efficiency in the production of OH−via an approximate four-electron pathway. Additionally, a fair comparison supported by transmission electron microscopy and electrochemical data shows that the shapes of Pd nanocubes coated with multi-armed Pt shells are nearly unchanged by the ORR and that these core-shell catalysts show stabilities superior to Pd nanocubes.

Different-sized Ag/Sn nanoparticles were prepared using various tin salts, including tin(II) pyrophosphate, tin(II) oxalate, and tin(II) sulfate, and applied as activators for electroless copper deposition. The transmission electron microscopy and X-ray photon electron spectroscopy data showed Ag nanoparticles of 8.2 and 10.2 nm were prepared and coated by SnOxwhen tin(II) sulfate and tin(II) oxalate were used, respectively. When tin(II) pyrophosphate was employed, 5.8 nm Ag nanoparticles with a thicker shell composed of SnOxand Sn2P2O7were obtained. Furthermore, a comparison of the activities and actual deposition rates of these three Ag/Sn nanoparticles was carried out by monitoring the deposition in situ with a quartz crystal microbalance (QCM) and measuring the surface morphology of the deposited layer with a field-emission scanning electron microscope (FE-SEM). The activities and deposition rates observed by QCM had the order Ag/SnP2O7> Ag/SnSO4> Ag/SnC2O4, which demonstrated that the size of the Ag nanoparticles controls the activity of electroless copper deposition (ECD), even in the presence of a thick Sn shell. However, the FE-SEM images showed that a thick shell influenced the uniformity of deposited Cu film. Therefore, among these three Ag/Sn nanoparticles, the nanoparticles reduced by tin(II) sulfate showed the best performance as an activator for ECD.

Electrochemical surface areas (ESAs) were used to estimate the specific activities of different-sized Ag nanoplates (NPLs), which were used as novel catalysts for electroless copper deposition (ECD). Based on the consideration of ESAs and deposition kinetics measured using an electrochemical quartz crystal microbalance, the mean specific activities of NPLs with sizes of 74 nm, 117 nm, and 162 nm were determined to be 0.107, 0.250, and 1.017 mg·cm−2, respectively. The largest NPLs showed the highest activity. Simultaneously, in the Tafel plot normalized to the ESA, the specific current density corresponding to 74 nm < 117 nm < 162 nm NPLs for formaldehyde oxidation in the high overpotential region was determined. This anodic reaction activated with various NPLs could thus be the rate-determining step in ECD. Additionally, an untypical open circuit potential curve containing two mixed potentials for two period depositions—Cu deposition on Ag NPLs and Cu on the deposited Cu layer—was observed. In the intended application, conductive Cu patterns on a flexible polyimide film using Ag NPL ink of 2.5 wt% solid content were successfully fabricated by inkjet printing combined with catalyzed ECD.

Dispersions of Pd–NiO nanoparticles were electrochemically synthesized in a water-in-oil microemulsion, with fine control by appropriate adjustment of the concentration ratio of H2O to surfactant. The feasibility of using these Pd–NiO nanoparticles as a new activator for electroless Ni deposition (END) was examined. In this study, fast electroless deposition was achieved using Pd–NiO nanoparticles as a catalyst. A systematic study of the deposition kinetics and the mass activity by electrochemical quartz-crystal microgravimetry indicated that adding NiO to active colloids can shorten the induction time, and that reducing the particle diameter can accelerate END reactions because steady-state deposition is achieved more quickly.