A strategy to modulate the electrocatalytic activity of copper towards CO 2 reduction involving adsorption of acrylamide, acrylic acid and allylamine polymers is presented. Modification of electrodeposited copper foam with poly(acrylamide) leads to a significant enhancement in faradaic efficiency for ethylene from 13% (unmodified foam) to 26% at-0.96 V vs. RHE, whereas methane yield is unaffected. Effects from crystalline phase distribution and copper oxide phases are ruled out as the source of enhancement through XPS and in-situ XRD analysis. DFT calculations reveal that poly(acrylamide) adsorbs on the copper surface via the oxygen atom on the carbonyl groups, and enhances ethylene formation by i) charge donation to the copper surface that activates 1

Practical aspects of the modification of palladium on nickel wire electrodes were explored for the electrocatalytic applications of palladium-modified nickel (Pd/Ni) composite materials. In principle, Pd/Ni wire electrodes could be prepared via a simple galvanic replacement reaction, e.g., between tetrachloropalladate (PdCl 4 2− ) and Ni by simply immersing a piece of Ni wire into an aqueous solution of PdCl 4 2− . However, our preliminary trials at room temperature indicated that the reproducibility of the preparation is not good: in fact, Pd could not be modified on Ni in some cases even though we conducted the same preparation procedures. To improve the reproducibility of the modification, we studied the effects of pretreatments of Ni wire and the temperature of aqueous solutions. Consequently, it was found that the pretreatment with 1.0 M HCl aqueous solution and increased temperature, such as 50 °C, were effective to improve the Pd modification. The control of the modified states of Pd on Ni was found to be possible under the improved conditions by controlling the immersion time. For the comprehensive understanding of galvanic replacement reactions for preparing noble-metal-modified common metal wires, the results obtained using Pt precursors on Ni and the Pd modification on other metal wires, Fe, Cu, and Co, are shown and discussed compared with the case of Pd/Ni wire.

electrocatalysis fuel cell carbohydrate sensor multi-electron EC'mechanism catalyst heterogenisation A B S T R A C TThe enzymeless and operationally simple electrocatalytic oxidation of carbohydrates by "heterogenised" 4-benzoyloxy-TEMPO either (i) immobilised as microcrystals at a glassy carbon electrode surface or (ii) embedded into a polymer of intrinsic microporosity (PIM-EA-TB with 1027 m 2 g À1 BET surface area and highly rigid framework structure) has been studied in aqueous phosphate buffer of pH 12. It is shown that in contrast to microcrystal deposits, 4-benzolyoxy-TEMPO co-immobilised within PIM-EA-TB give stable catalytic responses for both, stationary and rotating disc electrode systems and for oxidation of glucose, sorbitol, and sucrose. The rigidity and intrinsic microporosity of PIM-EA-TB allow (slow) substrate and product diffusion, whilst maintaining 4-benzoyloxy-TEMPO immobilised in active molecular form.

The free radical 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4B-TEMPO) is active as an electrocatalyst for primary alcohol oxidations when immobilised at an electrode surface and immersed into an aqueous carbonate buffer solution. In order to improve the catalytic process, a composite film electrode is developed based on (i) carbon microparticles of 2-12 μm diameter to enhance charge transport and (ii) a polymer of intrinsic microporosity (here PIM-EA-TB with a BET surface area of 1027 m 2 g −1 ). The latter acts as a highly rigid molecular framework for the embedded free radical catalyst with simultaneous access to aqueous phase and substrate. The resulting mechanism for the oxidation of primary alcohols is shown to switch in reaction order from first to zeroth with increasing substrate concentration consistent with a kinetically limited process with competing diffusion of charge at the polymer layer-electrode interface (here the BLEk^case in Albery-Hillman notation). Reactivity optimisation and screening for a wider range of primary alcohols in conjunction with DFT-based relative reactivity correlation reveals substrate hydrophobicity as an important factor for enhancing catalytic currents. The PIM-EA-TB host matrix is proposed to control substrate partitioning and thereby catalyst reactivity and selectivity.

Gold modified nickel (Ni) electrodes were prepared via a simple galvanic replacement reaction between chloroauric acid (AuCl4−) and Ni base materials. Au nano‐ or micro‐structures were deposited on the Ni surface by immersing Ni disk/wire electrode in an aqueous solution of AuCl4−. The concentration of AuCl4− and the immersion time were systematically varied, and the surfaces of Ni wire were characterized by scanning electron microscopy (SEM). Furthermore, electrochemical responses of ferrocyanide, uric acid and glucose were observed with Au modified Ni wire electrodes prepared at lower concentrations of AuCl4− (below 1.0×10−4 M) after fixing some conditions. Consequently, reversible electrochemical responses of ferrocyanide could be observed even for Ni wire treated with 1.0×10−6 M AuCl4−, though no deposition was observed in the SEM measurements. Also, control of electrocatalytic activity was possible below 1.0×10−4 M AuCl4− for uric acid and glucose. Judging from the tunable electrocatalytic performance, simplicity of preparation, and the cost of electrode materials, we believe that Au modified Ni electrodes holds promise for applications in electroanalysis. On the other hand, in our preliminary trials, the properties of deposited Au nano‐ or micro‐particles were found to be sensitive to several factors. Further work is needed to achieve quantitative Au deposition over individual electrodes.

No abstract

Rocking disc electrode voltammetry (RoDE) is introduced as an experimentally convenient and versatile alternative to rotating disc voltammetry. A 1.6 mm diameter disc electrode is employed with an overall rocking angle of Θ = 90 degree applied over a frequency range of 0.83 Hz to 25 Hz. For a set of known aqueous redox systems (the oxidation of Fe(CN)6 4in 1 M KCl, the reduction of Ru(NH3)6 3+ in 0.1 M KCl, the oxidation of hydroquinone in 0.1 M pH 7 phosphate buffer, the oxidation of Iin 0.125 M H2SO4, and the reduction of H + in 1 M KCl)

No abstract