Transfer coefficient in electrochemical reactions

Abstract

We now turn to a summary of this work with Cu and closely related previous work without Cu.A. Ru(00I) without Cu.5 67"1 1. Ketene adsorbs at 105 K on Ru(001) with at least two molecular states [ 3 (C, C, O) and r¡2 (C, C)] and one dissociative state (CH2 and CO).2. Heating a saturation exposure of ketene above 200 K results in two competing channels of chemistry: (a) hydrogenation of ketene to 2 (C, O) CH3CHO and 2 (C, O) CH3CO and (b) CCH3 formation from CH2 coupling.B. 6Cu < 1 ML. 1. Submonolayer amounts of Cu block Ru sites and decrease the amount of ketene reaction/decomposition. Reaction forms of ketene on Ru(001) at 105 K are replaced by unreactive -bonded ketene on Cu.2. The CCH3 yield is suppressed linearly as Cu is added.3. The ketene hydrogenation yield drops as the Cu coverage increases. In addition, the selectivity is significantly shifted from r,2 (C, O) CH3CHO to 2 (C, O) CH3CO for Cu coverages between 0 and 0.4 ML. This shift is the result of less C-H bond breaking to supply H for hydrogenation.C. 1 < dCu< 2 ML. 1. Ketene is -bonded to monolayer Cu on Ru(001). The desorption temperature (170-250 K) and the HREELs c(CH2) frequency both indicate that the interaction of ketene with the first Cu layer is considerably stronger than with subsequent layers.2. A small amount of ketene decomposition (<0.1 ML) occurs for 1 ML of Cu and is ascribable to sites in the overlayer that expose Ru for bonding with the oxygen in ketene.D. 6Cu > 2 ML. 1. Ketene is weakly -bonded to Cu overlayers above 2 ML and desorbs, without measurable decomposition, only a few degrees above its physisorbed desorption temperature (122 K).2. The structure and reactivity of ketene on Cu coverages above 2 ML are the same regardless of the thickness of the Cu overlayer.

Facile Synthesis of an Efficient Ni–Fe–Co Based Oxygen Evolution Reaction Electrocatalyst

“…The change in the Tafel slope could be associated with the change in the transfer coefficient, α, from an initial value of 1.25 to unity. Based on the Marcus's theory, 95,96 the decrease in the transfer coefficient could be directly related to increase in the total reorganization energy of the redox system. Supplementary Fig.…”