China 
Africa 
Explore chapters and articles related to this topic
Solid Polymer Electrolyte Membranes
Published in Asit Baran Samui, Smart Polymers, 2022
Swati S. Rao, Manoranjan Patri
As mentioned in Section 14.1.1, polymer electrolyte membranes contain ionizable acid groups which dissociate into immobile anionic and mobile cationic moieties. The cations, particularly the protons in the case of proton exchange membranes used for fuel cell applications, are the mobile species which are responsible for the conduction mechanism and the overall functioning of the membrane as an electrolyte. Transport of protons in a membrane takes place via two mechanisms, namely, the Grotthuss mechanism and the vehicular mechanism. The Grotthuss mechanism, commonly known as the hopping mechanism, involves the movement of the proton through a hydrogen-bonded framework. In the presence of excess water, the proton transfer mechanism is similar to that of bulk water. Here the proton is transferred through the formation and cleavage of covalent bonds. In the vehicular mechanism, the transfer of the proton takes place by diffusion of the proton. Here the water molecules act as vehicles to transport the proton species from the anode to the cathode by the formation of H3O+. The mechanism through which proton transfer takes place depends on the humidity level and temperature of operation of the fuel cell.
Proton Transport Mechanisms in Nanofibers Ion Exchange Membrane
Published in Ahmad Fauzi Ismail, Nidal Hilal, Juhana Jaafar, Chris J. Wright, Nanofiber Membranes for Medical, Environmental, and Energy Applications, 2019
Nuha Awang, Ahmad Fauzi Ismail, Juhana Jaafar, Mohd Hafiz Dzarfan Othman, Mukhlis A. Rahman
Membrane morphology is very important in providing a new configuration of PEM with addition of electrospun fibers also responsible for improved proton conductivity. The Grotthus mechanism (proton hopping) plays an important role in bringing the proton from one site to another (Zhao et al., 2006). The protons are delivered through ionic cluster channels (free water and SO3 that linked with non- freezing bound water) (Qin et al., 2009, Wu et al., 2009). It is desirable for a membrane to have high quantity of bound water (so called non-freezing bound water) since it is a crucial element in delivering protons. The study proved that the presence of Cloisite was an important factor that helped reduce the hydration in membrane by the Cloisite retaining water (Awang et al., 2018). Water retention capability of Cloisite has successfully enhanced the proton conductivity of the electrospun SPEEK/Cloisite nanofibers membranes. The increase in the proton conductivity of the nanocomposite membrane can be interpreted in the following way (Figure 12.5).
Nanoscale electrokinetic phenomena
Published in Zhigang Li, Nanofluidics, 2018
Proton transport is a key issue in biological membranes and energy devices, such as fuel cells. In a bulk electrolyte, the solvation of excess protons is idealized as Eigen cations (H9O4+) and Zundel (H5O2+) cations. In an Eigen cation complex, there is a hydronium ion (H3O+) at the center, which is strongly hydrogen-bonded with three water molecules. A Zundel cation, however, has a symmetric structure with a proton shared by two water molecules. Protons usually transport via the well-known “Grotthuss mechanism,” which suggests that excess protons shuttle through the hydrogen bond network of water molecules via the formation and breaking of covalent bonds with neighboring molecules. In a bulk solution, excess protons switch between Eigen cations and Zundel cations frequently, which lead to a popular mechanism for proton transport, i.e., the “Eigen ‒ Zundel ‒ Eigen” scenario.
Prospects on utilization of biopolymer materials for ion exchange membranes in fuel cells
Published in Green Chemistry Letters and Reviews, 2022
Angelo Jacob Samaniego, Richard Espiritu
There are two generally accepted mechanisms of proton transport inside the membrane: Grotthuss (60) and Vehicle mechanism (61). The Grotthuss mechanism describes the proton transport via hopping or jumping of proton (H+) through the neighboring lone electron pair to that of another. This proton jump usually occurs in the regions where -OH ions are interacting with -SO3H clusters by hydrogen bond (Figure 8). On the other hand, in the Vehicle mechanism, proton transfer proceeds via diffusion and movement of hydronium ion (H3O+) with water molecules through the hydrophilic channels in the structure of the composite membrane (Figure 8). Membranes with sulfonation degree of 2.34 and sNCC content of 5 wt% achieved better proton conductivities of 240 mS cm−1 at 80°C than the previously reported study by Ni et al. (58), though tensile strength and elastic modulus values were lower at 15 and 357 MPa, respectively.
Energy generation by membraneless microfluidic fuel cell using acidic wastewater as a fuel
Published in International Journal of Ambient Energy, 2021
Rasha H. Salman, Khalid M. Abed, Hassanain A. Hassan
For the current microfluidic fuel cell, the following assumptions were set: 1D system: This is acceptable for a thin porous medium like the Whatman filter paper.Air-breathing: Air is obtained from the continuous exposure of the thin film to air to supply O2 for the cathodic reaction.pH < 7: An extremely acidic fuel supplied to the anode (with pH ≤ 1).One direction of reaction.Proton is transferred due to the Grotthuss Mechanism.No thermodynamic stability.No flow accumulation.The system is isothermal and both the fuel and the oxidant are pressure-driven steady incompressible flows.The products of the overall reaction can be removed naturally by the flowing streams.
Crystal structures, proton conductivities and luminescence of two organic-inorganic hybrid materials based on Keggin-type clusters and Cu(II)/Cu(I)-bis(hydroxymethyl)-2,2′-bipyridine complexes
Published in Journal of Coordination Chemistry, 2021
Yan Zhao, Xianying Duan, Guangguang Zhang, Meilin Wei
For the proton conductors, one of the necessary conditions should be proton carriers. In 1, there are proton carriers from bhmbpy organic ligands (–CH3OH) and coordinated water molecules. In 2, there are proton carriers from bhmbpy organic ligands (–CH3OH) and free protons for charge balance. Thus, their proton conductivity of 1 and 2 should originate from these protons. In both compounds, there are not only protons as possible carriers but also in the hydrogen-bonding frameworks. Moreover, some solvent water molecules are not lost below 100 °C. Therefore, the mechanism of proton conduction of both compounds is expected to be similar to that of the Grotthus mechanism [14, 31].