Hydrogen Evolution Reaction HER

Figure 3.16 Volcano plot for the hydrogen evolution reaction (HER) for various pure metals and metal overlayers. Values are calculated at 1 barof H2 (298K) and at a surface hydrogen coverage of either 0.25 or 0.33 ML. The two curved lines correspond to the model (3.24), (3.25) transfer coefficients (not included in the indicated equations) of 0.5 and 1.0, respectively, have also been added to the model predictions in the figure. The current values for specific metals are taken from experimental data on polycrystalline pure metals, single-crystal pure metals, and single-crystal Pd overlayers on various substrates. Adapted from [Greeley et al., 2006a] see this reference for more details.

Hammer-Nprskov d-band model, 70, 272-273, 327 Heme-copper oxidase, 610 High Throughput Synthesis of Nanoparticles, 572-574 Hydrogen (underpotential) adsorption, 60-63,254, 471-484, 526 Hydrogen evolution reaction (HER), 31, 79-87... [Pg.695]

The only cathodic process in HF solutions is the hydrogen evolution reaction (HER), which is important in that it is involved in almost all reactions at both anodic and cathodic potentials. The silicon electrode can be passivated by hydrogen termination... [Pg.315]

The actual current passed / = 2F/4Jt,[H + ]exp[ — J pAE] since two electrons are transferred for every occurrence of reaction I. Equation (1.64) constitutes the fundamental kinetic equation for the hydrogen evolution reaction (her) under the conditions that the first reaction is rate limiting and that the reverse reaction can be neglected. From this equation, we can calculate the two main observables that can be measured in any electrochemical reaction. The first is the Tafel slope, defined for historical reasons as ... [Pg.38]

Reaction mechanism graphs may be useful in studying reaction mechanisms even when there is no species cycling through the reaction. To see this, consider the simple example of the electrochemical hydrogen evolution reaction (HER) mechanism. Here the overall reaction is 2H20 +2e / 20H + H2. The elementary reaction steps that combined to yield HER (cf. Fishtik etal., 2005)26 are... [Pg.209]

Reaction layerthickness — An electrochemical reaction (e.g., hydrogen evolution reaction HER) maybe associated with a preceding chemical reaction (i.e., dissociation of a weak acid in this example) according to... [Pg.568]

CO oxidation when deposited on C03O4, Fe20j, or Ti02- Electro-catalytic properties can also be related to the particle size. It was shown for example that Pt nanoparticles synthesized by radiolysis and supported on graphite powder exhibit different activities toward the hydrogen evolution reaction (HER) depending on their size and their surface morphology. ... [Pg.358]

The recent spectroscopic and monocrystal results are in agreement with earlier observations on the extensively studied hydrogen evolution reaction (HER). This reaction proceeds via the following steps ... [Pg.246]

While it is expected that electrocatalytic reactions on Ru surfaces should be strongly structure-sensitive, the first report on structural effects on hydrogen oxidation and evolution reactions appeared only recently The structural effects in the hydrogen oxidation reaction (HOR) and the hydrogen evolution reaction (HER) may be factors affecting the performance of hydrogen fuel cell anodes. [Pg.21]

The chemical reactivity of CO2 is low. However, the equilibrium potentials of CO2 reduction are not very negative as compared with that of the hydrogen evolution reaction (HER) in aqueous electrolyte solutions. For example, electrochemical reduction of CO2 to HCOO in aqueous solution is given below together with the standard electrode potential at pH 7.0 at 25°C with respect to the standard hydrogen electrode (SHE). [Pg.90]

Bockris and Uosaki93 108,109 calculated photocurrent-potential relations mainly for the hydrogen evolution reaction (HER) at p-type semiconductors with the assumption that the following is the ratedetermining step ... [Pg.38]

In most environments of interest to corrosion, there is not a large concentration of metal ions acting as cathodic reactants. The important cathodic reactions in corrosion mechanisms involve water. There are two primary cathodic reactions, each of which takes a different form in acids or bases. The first is the hydrogen evolution reaction (HER), in which hydrogen gas is evolved. [Pg.15]

The hydrogen evolution reaction (HER) is an interesting multistep reaction to discuss because it is relatively simple and very important in corrosion. In adds, the electrode reaction for hydrogen evolution is ... [Pg.33]

Hydrogen can be evolved during the corrosion of metals in aqueous solutions. The hydrogen evolution reaction (HER) involves the cathodic reduction of hydrogen ions in acid solutions (Reaction 1) or of water in alkahne or neutral solutions (Reaction 2) ... [Pg.108]

Using the following data for the corrosion of iron in hydrogen-saturated, oxygen-free solution, calculate (a) the corrosion rate and (b) the exchange current density for the hydrogen evolution reaction (HER) on iron ... [Pg.631]

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