China
Africa
Explore chapters and articles related to this topic
Sustainable Energy
Published in Stanley E. Manahan, Environmental Chemistry, 2022
Fuel cells are devices that convert the energy released by electrochemical reactions directly to electricity without going through a combustion process and electricity generator. Fuel cells are the primary means for utilizing hydrogen fuel (see Section 18.16) and are becoming more common as electrical generators. A fuel cell has an anode at which elemental hydrogen is oxidized, releasing electrons to an external circuit, and a cathode at which elemental oxygen is reduced by electrons introduced from the external circuit, as shown by the half-reactions in Figure 18.7. The H+ generated at the anode migrate to the cathode through a solid membrane permeable to protons. The net reaction is 2H2+O2→2H2O+electricalenergy
Renewable Energy
Published in Chitrarekha Kabre, Synergistic Design of Sustainable Built Environments, 2020
The anode is the electrode at which oxidation (loss of electrons) takes place. In a fuel cell, the anode is electrically negative. The anode is composed of platinum particles uniformly supported on carbon particles. The platinum acts as a catalyst, increasing the rate of the oxidation process. The anode is porous so that hydrogen can pass through it.
Voltage, Capacitors, and Batteries
Published in Juan Bisquert, The Physics of Solar Energy Conversion, 2020
In Figure 3.3a we show that a negative bias voltage is applied to the left electrode, which is termed the cathode, and this is where electrons tend to flow inside the device. The effect of positive bias at the left electrode is shown in Figure 3.2b. The positively biased electrode is termed the anode. (Note that by convention the direction of a positive electric current flow is that of the positive charges.)
Plasma synthesis of ammonia by asymmetric electrode arrangement
Published in Materials and Manufacturing Processes, 2023
F. Baharlounezhad, M.A. Mohammadi, M.S. Zakerhamidi
Electrolysis is the process of passing an electric current through the material to cause a chemical change. This process takes place in an electrolytic cell, a reactor consisting of cathode and anode electrodes immersed in a solution containing positive and negative charged ions. An electrolytic cell, also known as an electrolysis reactor, converts electrical energy into chemical energy. Metal conductors are used as electrodes in electrolysis reactors. Electrodes are responsible for the transmission of electrons in certain circumstances and are also engaged in electrolysis processes in others. The cathode is the electrode that sends electrons to the anode across the electrolyte environment, and the anode is the electrode that receives electrons from the cathode. Electrolysis is widely used in metallurgical engineering [42,43] like electrowinning,[44,45] electrorefining,[46–48] and electroplating.[49,50] The electrodes of an electrochemical system with asymmetric electrode configurations might differ in form, size, material, and design from one another.
Protection against reinforcement corrosion using various hydroxy acid-based rust converters: tests in mortar medium
Published in European Journal of Environmental and Civil Engineering, 2020
Muhammad Salman, Muhammad Ali Sikandar, Hassan Nasir, Muhammad Waseem, Shahid Iqbal
Additionally, it is presumed that in malic, lactic and tartaric acid, the corrosion inhibition is not limited to the passivation effect but is also due to the active dissolution of Fe2+ ions to form insoluble complexes, whereas, in the case of glycolic acid, the chelating agent tends to adsorb onto steel rebar, thereby, blocking the ingress of harmful Cl- ions. The chelating action is presumed to occur as follows: Firstly, anions from malic, tartaric and lactic acids can complex with Fe2+ ions to form ferrous-malate, ferrous tartrate and ferrous lactate, respectively; which in the presence of oxygen are oxidised into their respective ferric compounds. Additionally, these anions can react to form ferric compounds directly with Fe3+ ions. Sometimes, Fe3+ oxides can be reduced to Fe2+ ions that can further complex with anions from rust converters. The corrosion mechanism includes the electrochemical reactions between the anode, usually mild steel and the electrolyte (acid-based rust converters). It is reported elsewhere (Gorman & Clydesdale, 1984) that complexes of malate and lactate with iron are highly kinematically stable, which leads to forming a stable oxide layer around steel rebar. It is worth mentioning that this reaction is thermodynamically feasible in an alkaline solution of pH >12 (Pourbaix, 1974). The following equations govern the passivating effect of hydroxy acids on steel rebar.
Effect of cathodic protection methods on ferrous engineering materials under corrosive wear conditions
Published in Corrosion Engineering, Science and Technology, 2020
F. Brownlie, L. Giourntas, T. Hodgkiess, I. Palmeira, O. Odutayo, A. M. Galloway, A. Pearson
An alternative cathodic protection methodology is SACP, in which a metallic alloy, which is more active than that of the protected metal alloy, is utilised to create a galvanic cell. Therefore, the current is supplied by the preferential corrosion of the more active metal called a sacrificial anode. Common materials used as sacrificial anodes for the protection of steels are zinc-based alloys, aluminium-based alloys and magnesium-based alloys [12]. The advantages of using sacrificial anodes are as follows: easy installation, inexpensive maintenance and low capital cost. The main disadvantages of using sacrificial anodes are that periodic replacement of the anodes during scheduled maintenance may be required and the galvanic current available is dependent on the sacrificial anode area [14].