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The Standard Model (SM) and the goal of force unification The unification of gravitational, Strong and Weak Forces has been a long-sought goal [1-3]. In general, force unification refers to the idea that it is possible to view all of the forces of nature as manifestations of one single, all-encompassing force. Today, within the context of the Standard Model (SM) of elementary particles, [7] scientists seek to unify Gravity with the Strong force under a Grand Unified Theory which binds quarks together and is responsible for the stability of atomic nuclei. These efforts have not been successful yet, most likely because the SM neglects neutrinos [8,9], gravity [4], special relativity [10] and quantum mechanics [11].

The neutrino mass values extracted from the pioneering Nobel Prize winning measurements of Kajita and co-workers at Superkamiokande were used in the classical Newton-Laplace equation for computing the speed of propagation of acoustic waves in gases comprising neutrinos. It is found that, surprisingly, acoustic waves in the lightest neutrino environments proceed with the speed of light in vacuum

We discuss the similarities and differences between catalysis/electrocatalysis of chemical processes, such as ammonia synthesis or H2O electrolysis on one hand, and of nuclear catalytic processes, commonly called baryosynthesis, such as the synthesis of neutrons and protons from quarks, on the other. In chemical synthesis the underlying forces are well known to be electrostatic in nature while in the synthesis of hadrons or nuclei from quarks (known as hadronization or nucleosynthesis) the underlying forces are known as the Strong nuclear forces, whereas if electrons are also involved, as Weak nuclear forces. Here we discuss for the first time from a catalytic viewpoint the importance of some recent developments in our understanding of the structure and synthesis of hadrons via a model entitled Rotating Lepton Model (RLM), which is quite similar to the Bohr model of the H atom used in Chemistry but which has shown that the Strong Force is a gravitational force between three very fast (relativistic) neutrinos, rotating symmetrically on a circular orbit, whose gravitational masses and gravitational attraction increases dramatically with increasing rotational speed, according to the theory of Special Relativity (SR), thus reaching the masses of quarks and the value of the Strong Force respectively. We show that, interestingly, positrons and electrons, which quite often play a very important and well established catalytic role in chemical synthesis due to their electrical charge, also play an equally important and central catalytic role in nuclear synthesis due to their enormous mass, relative to the mass of the neutrinos, and the concomitant dramatic acceleration of neutrinos to ultrarelativistic speeds and huge mass increase, resulting to enhanced very strong gravitational binding between them which reaches the value of the Strong Force. Consequently, electrons and positrons are the dual, electrostatic and gravitational, catalysts of our Universe for the production of chemicals and baryons.

The reaction of CO2 hydrogenation is of high environmental interest since it allows for the transformation of the logistically challenging H2, gained from renewable sources, to the much more manageable hydrocarbons. Ruthenium is a catalyst widely used to produce methane from CO2. In this study we present an example of how Electrochemical Promotion of Catalysis (EPOC) can elucidate the role of solid electrolytes (YSZ, BZY) supporting Ru porous films or nanoparticles. It is found that the sign of the charge (-/+) of the current-conducting species of the electrolyte has a profound effect on the selectivity of Ru during CO2 hydrogenation. Using this insight, we have developed and tested a new supported Ru-Co catalyst for the production of higher hydrocarbons.

The electrochemical promotion of catalytic activity by non-noble transition metals is rarely reported in the literature. Here, Co nanoparticles were utilized for the electrochemical activation of C...

We analyze the dependence on neutrino energy of the gravitational attraction between ultrarelativistic neutrinos using Special Relativity and the equivalence principle of inertial and gravitational mass. It is found that when accounting for the special relativistic increase in particle mass with particle speed, then this gravitational force reaches the value of the Strong Force at a neutrino energy of 313 MeV, corresponding to the effective mass of a quark. This force can sustain the rotational motion of self-gravitating neutrino trios or electron/positron-neutrino pairs, and thus lead to the self driven generation of mass, i.e. of hadrons and bosons, the masses of which can be computed with an astonishing precision of 1\% without any adjustable parameters.

The majority of the kinetic studies reported in the literature for heterogeneously catalyzed reactions, take place on laboratory scale reactors. In the present study, the kinetic mechanism of electrochemical promotion of CO2 hydrogenation was investigated using a scaled up, monolithic electropromoted reactor (MEPR) loaded with nine parallelly connected Ru/YSZ/Au electrochemical cells. The study was carried out under atmospheric pressure, at 370 °C, with a flowrate of 1000 cm3/min and over a wide range of reactants partial pressures. The morphological and electronic characteristics of the catalyst surface, before and after reaction, were thoroughly investigated with a variety of techniques including X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). It was shown that increasing the partial pressure of H2 (electron donor) leads to an increase in the methane production rate with a concurrent decrease of CO formation. Methanation emerges with a positive order in H2 whereas the RWGS with a negative one. Increasing the partial pressure of electron acceptor (CO2) leads to the opposite behavior. Based on the kinetic results and the rules of chemical and electrochemical promotion, an electrophobic behavior (increase of the rate with increasing catalyst potential) is expected for the methanation reaction and an electrophilic (decrease of the rate with increasing catalyst potential) for the RWGS reaction. Both predictions are confirmed experimentally. The results are in agreement with previous studies on CO2 hydrogenation in laboratory scale reactors demonstrating the successful design and operation of the current scaled up electropromoted system (MEPR).

In two recent works we have shown that the masses of the W ± and Z o bosons can be computed from first principles by modeling these bosons as bound relativistic gravitationally confined rotational states consisting of e ± – ν e pairs in the case of W ± bosons and of a e + – ν e – e − triplet in the case of the Z o boson. Here, we present similar calculations for the Higgs boson which we model as a bound rotational state consisting of a positron, an electron, a neutrino and an antineutrino. The model contains no adjustable parameters and the computed boson mass of 125.7 GeV/c 2 , is in very good agreement with the experimental value of 125.1 ± 1 GeV/c 2 . The thermodynamics and potential connection of this particle with the Higgs field are also briefly addressed.

Studies on CH4 oxidation are of special interest due to the difficulty in activating this particular hydrocarbon, due to the demand of an active catalyst at low temperatures (T50 at 300°C) as well as due to possible deactivation of the catalyst upon exposure at high temperatures [1]. To address these issues, we used Electrochemical Promotion of Catalysis (EPOC), which was discovered in the early 80's and has been studied for more than 100 catalytic systems [2]. EPOC allows for the controlled enhancement of the catalytic activity by potential or small current application between a catalyst (working electrode) supported on a solid electrolyte and an auxiliary electrode. In this study, Pd nanoparticles (2-4 nm) deposited on O2- conductor (YSZ) was used to study the electrochemical promotion of methane oxidation. It was found that EPOC could be used to promote nanodispersed catalysts and enhance the reaction rate at temperatures lower than those that have been observed in previous studies [3,4]

Steady state multiplicities can occur in hydrated Nafion membranes of polymer electrolyte membrane (PEM) fuel cells. In this phenomenon, the current-potential curves cell exhibit under certain conditions steady state multiplicity, i.e. for a fixed current value, there are two corresponding cell potential values and thus the current versus potential curve exhibits a local current maximum. In this work, steady state multiplicities have been studied varying basic operating parameters of the PEMFC such as temperature and extend of hydration of the membrane and by poisoning the anode via CO supply. In every case there was a comparison between the experimental data and the γ-model developed in our previous studies.

The triode operation of humidified PEM fuel cells has been investigated both with pure H 2 and with CO poisoned H 2 feed over commercial Vulcan supported Pt(30%)-Ru(15%) anodes. It was found that triode operation, which involves the use of a third, auxiliary, electrode, leads to up to 400% power output increase with the same CO poisoned H 2 gas feed. At low current densities, the power increase is accompanied by an increase in overall thermodynamic efficiency. A mathematical model, based on Kirchhoff’s laws, has been developed which is in reasonably good agreement with the experimental results. In order to gain some additional insight into the mechanism of triode operation, the model has been also extended to describe the potential distribution inside the Nafion membrane via the numerical solution of the Nernst-Planck equation. Both model and experiment have shown the critical role of minimizing the auxiliary-anode or auxiliary-cathode resistance, and this has led to improved comb-shaped anode or cathode electrode geometries.

We compare the thermodynamics and catalysis of two important exothermic chemical reactions, the homogeneously catalyzed chain reaction of H2 oxidation and the heterogeneously catalyzed ammonia synthesis, with those of an important exothermic physical reaction, namely the proton or neutron synthesis from elementary particles, i.e. quarks or relativistic neutrinos, a process known as hadronization. We show that, surprisingly, hadronization has several similarities both with homogeneous autocatalytic chain reactions, as well as with heterogeneously catalyzed ammonia synthesis. In NH3 synthesis, the presence of electrical charge, namely alkali promoters or protons or electrons on transition metals, enhances the formation of catalytically active intermediate NH species, while in hadronization, free electrons or positrons lower the activation energy and facilitate the formation of catalytically active bosonic e±-neutrino intermediates. These entities liberate highly active neutrinos, creating, via their relativistic mass increase, a strong local gravitational field with all the mass-producing properties of the Higgs field. The main analogies and differences between the electric field effects in chemical catalysis and the electric and gravitational field effects in hadronization catalysis are identified and briefly discussed.

The magnitude of the activation overpotential for an electrocatalytic reaction occurring at the electrode/solid electrolyte tpb or interface depends crucially on the exchange current density i0. The exchange current density i0 is a measure of the electrocatalytic activity of the tpb or, more generally, the electrode/solid electrolyte interface for a given electrocatalytic reaction. The interesting role which solid electrolytes can play in the study of heterogeneous catalysis was first recognized by Wagner, who proposed the use of solid electrolyte cells for the measurement of the activity of oxygen on metal and metal oxide catalysts. Electrocatalysis plays an important role in the efficient operation of solid electrolyte fuel cells used for power generation. Catalysis at the anode also has a significant role. Electrocatalysis in solid electrolyte cells can also be used to activate catalysis on the gas-exposed electrode surfaces. This novel application of solid electrolytes is of great importance both in electrochemistry and in heterogeneous catalysis.

The electrochemical promotion of the CO2 hydrogenation was investigated, using a monolithic electropromoted reactor (MEPR) loaded with nine, connected in parallel, Ru/YSZ/Au electrochemical cells. The study was carried out at ambient pressure and in the temperature range between 220°C and 370°C, using high reactant flowrates (up to 2500 cm3/min) and reducing conditions (PCO2/PH2=1/7). For an intermediate flowrate of 1000 cm3/min, the selectivity to methane (SCH4) was 100 % for temperatures up to 300°C. Further increase in temperature resulted to a decrease in selectivity to methane with a concomitant increase of the corresponding yield (YCH4) due to the higher CO2 conversion. However, the total performance of the reactor, in terms of methane selectivity and yield, was affected significantly under electropromoted conditions. At the maximum studied temperature of 370°C, the unpromoted values of SCH4 and YCH4 were 84 % and 24 % respectively, while O2− supply to the catalytic surface enhanced theses values to 92 % and 32 % respectively. The qualitative features of electropromotion, i.e. electrophobic behavior for methanation and electrophilic behavior for the RWGS reaction, were in agreement with previous EPOC studies of CO2 hydrogenation in laboratory scale reactors showing a successful scale up of Electrochemical Promotion of Catalysis (EPOC). In addition, the good performance of the monolithic reactor under severe operating conditions of high flowrates and temperatures is a promising result for further scale-up and for the practical utilization of EPOC.

In a recent work we have shown that the mass of W ± bosons can be computed from first principles by modeling these bosons as relativistic rotational bound states consisting of e ± – ν e pairs, and by employing the de Broglie wavelength equation together with Newton’s universal gravitational law but with gravitational instead of rest masses (Vayenas et al., 2016). Here, we present similar calculations for the Z o boson which we model as a bound state of e + – ν e – e − with an electron antineutrino at the center of the rotating ring. This appears consistent with the fact that Z o bosons are known to decay primarily to e + – e − pairs. The above models contain no adjustable parameters. The computed Z o boson mass ( 91.72 GeV / c 2 ), as well as the ratio of the masses of Z o and W ± bosons, differ by less than 0.6% and 0.9% respectively from the experimental values.

Using Newton’s universal gravitational law but with gravitational instead of rest masses, and the de Broglie wavelength equation, we show by computing from first principles their mass that the W + and W − bosons correspond to relativistic e + − ν e and e − − ν e rotating pairs. This appears consistent with the fact that W + and W − bosons are known to decay to e + − ν e and e − − ν e couples, respectively. The model contains no adjustable parameters and in addition to the computed masses, potential energies, decomposition temperatures, and lifetimes, are in good agreement with experiment. This agreement can be further improved upon considering, in addition to the relativistic gravitational force, the Coulombic charge-induced dipole interactions between the charged components (positrons or electrons) and the polarizable neutrinos.

We use the Rotating Lepton Model (RLM) of elementary particles in conjunction with special relativity and the de Broglie equation to compute analytically the masses of neutrinos from the masses of composite particles, such as hadrons, in the structures of which neutrinos have been recently shown to participate. In this way, three distinct neutrino masses are computed which are in good agreement with the values obtained experimentally at Superkamiokande for the three neutrino flavors of the Normal Hierarchy.

Recycling CO2 into a carbon-neutral source is a beneficial approach in reducing non-renewable energy sources. Herein, the electrochemical promotion of catalysis (EPOC) has been exploited to enhance the catalytic activity of Ru nanoparticles (0.7−1 nm) deposited on the proton conductor yttria-doped barium zirconate (BZY), as free-standing nanoparticles and supported on Co3O4 semiconductor, for CO2 hydrogenation. Under 250−450 °C and atmospheric pressure, both methanation and reverse water-gas shift (RWGS) reaction take place simultaneously over the Ru nanoparticles with a superior selectivity to CO. Under anodic polarization, free-standing Ru nanoparticles displayed an increase in CH4 and a decrease in CO production, while the opposite effect was observed under cathodic polarization. Ru supported on Co3O4 displayed a superior catalytic activity mostly due to enhanced metal–support interactions. The electronic effects induced by the pairing of Co3O4 and BZY resulted in a new approach to EPOC applications that brings it closer to industrial application.

The rotating lepton model (RLM) of composite particles is used in conjunction with special relativity, the equivalence principle of inertial and gravitational mass, and the de Broglie wavelength equation, to compute analytically the masses, potential energies and Hamiltonians of 9 hadrons, 3 mesons and 3 bosons without any adjustable parameters. The model is also used to derive analytical formulae for their confining force and internal pressure and to compare with the experimental values measured recently via deeply virtual Compton scattering (DVCS) and computed via lattice Quantum Chromodynamics (LQCD) calculations. Agreement between the RLM computed masses and the experimental ones is, surprisingly, within 1% and supports the previously proposed notion that the strong force can be modeled as a relativistic gravitational force between neutrinos, and that the weak force can be modeled as a relativistic gravitational force between electrons or positrons with neutrinos or antineutrinos.

Fuel cells present a highly efficient and environmentally friendly alternative technology for decentralized energy production. The scope of the present study is to provide an overview of the technological and commercialization readiness level of fuel cells. Specifically, there is a brief description of their general advantages and weaknesses in correlation with various technological actions and political strategies, which are adopted towards their proper positioning in the global market. Some of the most important key performance indicators are also discussed, alongside with a few examples of broad commercialization. It is concluded that the increasing number of companies which utilize and invest on this technology, in combination with the supply chain improvements and the concomitant technological maturity and recognition, reinforce the fuel cell industry so as to become well-aligned for global success.

The electrochemical promotion of the hydrogenation of CO 2 on porous Ru catalyst–electrodes supported on K–β″–Al 2 O 3 , a K + conductor, was investigated at temperatures 280 °C to 420 °C and atmospheric total pressure. Methane and CO were the only detectable products and the selectivity to CH 4 was varied reversibly between 0.01 and 98% by varying the catalyst potential between −0.8 V and 0.4 V, which corresponds to a change in the K + coverage on the catalyst surface between 0.32 and zero. The rate of CO formation increases monotonically with increasing K + coverage θ K + , and thus with decreasing potential, i.e. it exhibits electrophilic behavior, while the rate of CH 4 formation is an overall decreasing function of θ K + , i.e. it exhibits electrophobic behavior. However, for lower temperatures the methanation rate exhibits a local maximum at intermediate θ K + and potential values, exhibiting volcano-type behavior. This minimum shifts to lower potentials with increasing hydrogen partial pressure and increasing temperature. The results are in very good agreement with the rules of electrochemical and classical promotion.

We formulate a Bohr-type rotating particle model for three light particles of rest mass m o each, forming a bound rotational state under the influence of their gravitational attraction, in the same way that electrostatic attraction leads to the formation of a bound proton–electron state in the classical Bohr model of the H atom. By using special relativity, the equivalence principle and the de Broglie wavelength equation, we find that when each of the three rotating particles has the same rest mass as the rest mass of a neutrino or an antineutrino (∼0.05 eV/c2) then surprisingly the composite rotating state has the rest mass of the stable baryons, i.e. of the proton and the neutron (∼1 GeV/c2). This rest mass is due almost exclusively to the kinetic energy of the rotating particles. The results are found to be consistent with the theory of general relativity. The model contains no unknown parameters, describes both asymptotic freedom and confinement and also provides good agreement with QCD regarding the QCD condensation temperature. Predictions for the thermodynamic and other physical properties of these bound rotational states are compared with experimental values.

The kinetics and the electrochemical promotion of the hydrogenation of CO2 over Ru-catalyst electrodes deposited on yttria-stabilized zirconia (YSZ) and (Na+)-β“-Al2O3 solid electrolytes are investigated at temperatures between 200 and 340 °C and pressures up to 5 bar. In the case of both the O2− conductor (YSZ) and the Na+ conductor (β”-Al2O3), the selectivity for CH4 production is enhanced significantly when using a positive potential by supplying of O2− to, or removal of Na+ from, the catalyst surface. The opposite effect is observed when using a negative applied potential, which suppresses CH4 formation and enhances the production of CO through the reverse water–gas shift reaction. However, at low Na coverage, and under reducing conditions, both methanation and H2 production are promoted by the application of a negative potential. The observed electrochemical promotion behavior in conjunction with the reaction kinetics is consistent with the rules of electrochemical and chemical promotion.

A simple kinetic model has been developed to describe the catalytic and electrocatalytic performance of Ni/GDC and Au–Ni/GDC anodes of SOFCs operating under internal methane-steam reforming reaction conditions, at low and high steam-to-carbon ratio values. The model accounts for the surface dissociation of CH4 to form methyl species which then react with H2O to form CO and H2. Under fuel cell operation conditions, two cases have been distinguished according to the observed electrochemical behavior; the high and the low steam-to-carbon ratio feed conditions. The former is characterized by electrochemical consumption of H2 and CO, produced by internal CH4 steam reforming, while the latter by electrochemical partial oxidation of CH4, to form H2 and CO, and oxidation of H2. Interestingly, the coverage of methyl-type species of the catalyst surface, as extracted from the model and the catalytic kinetic data, was found to coincide with the methyl species coverage at the three-phase boundaries, as extracted from the electrocatalytic experiments. The model is in good agreement with experiment under both open-circuit and fuel cell operation conditions.

An alternative approach for enhancing the Polymer Electrolyte Membrane Fuel Cell (PEMFC) performance under CO poisoning conditions was investigated by the use of the recently developed triode fuel cell design and operation. In this mode of operation a third, auxiliary, electrode is introduced in addition to the anode and cathode electrodes. It is shown that the application of electrolytic potential between the cathode and an auxiliary electrode can affect the performance of the fuel cell circuit in a controllable and reversible manner. The applied electrolytic current or potential can be fixed (steady-state) or can be cycled between chosen limits. In the present study, both triode operation modes were investigated and it was found that the time-averaged power output of the fuel cell can be increased up to three times.

The microstructure and electrochemical promotion of thin Pd catalyst-electrodes deposited on yttria-stabilized zirconia and prepared by sputter-deposition has been studied for the complete oxidation of propane and methane using steady state catalytic measurements in conjunction to electrochemical studies under lean conditions and at temperatures from 320 to 450 °C. It was found that propane oxidation is favoured on the metallic Pd film, while methane oxidation is enhanced after partial oxidation of the sputtered film in the course of the experiments. The observed rate changes under anodic polarization were strongly non-Faradaic and exceeded the electrocatalytic rate, I/2F, of O2− supply to the catalyst by up to a factor of 150 for methane and 250 for propane combustion. The catalytic rate increases only moderately by up to a factor of 2 and 3, respectively. For both reactions the catalyst-electrodes exhibit electrophobic behaviour, i.e. the rate increases with anodic polarization and decreases slightly with cathodic polarization.

The proton transport mechanism in fully hydrated Nafion 117 membranes was examined via electrochemical impedance spectroscopy (EIS) and steady-state current–potential measurements both in a symmetric H2, Pt|Nafion|Pt, H2 cell and in a H2, Pt|Nafion|Pt, air PEM fuel cell with hydrogen partial pressure values, P H 2 , varied between 0.5 kPa and 100 kPa. In agreement with recent studies it is found that for low P H 2 values the steady-state current–potential curves exhibit bistability and regions of positive slope. In these regions the Nyquist plots are found to exhibit negative real part impedance with a large imaginary component, while the Bode plots show a pronounced negative phase shift. These observations are consistent with the mechanism involving two parallel routes of proton conduction in fully hydrated Nafion membranes, one due to proton migration in the aqueous phase, the other due to proton transfer, probably involving tunneling, between adjacent sulfonate groups in narrow pores. The former mechanism dominates at high P H 2 values and the latter dominates in the low P H 2 region where the real part of the impedance is negative.

The effect of triode operation on the performance of CO poisoned PEM fuel cells was investigated. In this mode of operation a third, auxiliary, electrode is introduced in addition to the anode and the cathode. Application of electrolytic current in the auxiliary circuit, comprising the cathode and the auxiliary electrode was found to significantly enhance the time-averaged power output of a state-of-the-art PEMFC unit operating with a 70 ppm CO in H 2 atmospheric pressure mixture. Both normal and triode operation were found to lead to self-sustained current and potential oscillations in the fuel cell circuit over wide ranges of external resistive load. The time averaged increase in power output was found to be typically a factor of three higher than the power output in conventional fuel cell operation and up to a factor of 1.32 larger than the power sacrificed in the auxiliary circuit. The mechanism of the enhanced anodic electrocatalysis was investigated via the use of two reference electrodes and the results are discussed together with a possible design for application of the triode concept in stacks.

We have investigated the kinetics, rate oscillations and electrochemical promotion of CO oxidation on Pt deposited on YSZ using a standard oxygen reference electrode at temperatures 300-400 °C. We have found that electropromotion is small (p < 3) when the catalyst potential U WR , is below 0.4 V and very pronounced (p~ 9,Λ ~ 1500) when U WR exceeds 0.4 V. This sharp transition in the electropromotion behavior is accompanied by an abrupt change in reaction kinetics and in catalyst potential. For fixed temperature this transition, which leads to a highly active electropromoted state, occurs at specific P 1/2 O 2 /P CO ratio and catalyst potential. It is shown via comparison with independent catalyst potential-catalyst work function measurements that the transition corresponds to the onset of extensive O 2- spillover from YSZ onto the catalyst surface, and concomitant establishment of an effective double layer at the catalyst-gas interface, which is the cause of the highly active electropromoted state.

The technique of cyclic voltammetry was applied in conjunction with on-line catalytic product analysis to investigate the electrochemical promotion of NO reduction by C3H6 in presence of O2 on Rh catalyst-electrode films on YSZ at temperatures 350–490 °C. Cyclic linear potential sweep amperometry under catalytic reaction conditions leads to cyclic non-Faradaic electrochemical modifications in the CO2 formation and NO reduction rates which are compared to those obtained under steady state potentiostatic operation.

The performance of a monolithic electropromoted reactor was investigated under high gas flow rates, for the oxidation of ethylene utilizing thin (40 nm) tailor-structured highly porous skeletal Pt catalyst-electrodes coated on Y2O3-stabilized-ZrO2 (YSZ). Electrochemical enhancement was observed at gas flow rates as high as 25 L min−1 and mean gas residence times as low as 0.15 s. This is a promising step for the practical utilization of the electrochemical promotion of catalysis. An interesting feature of the skeletal Pt catalyst-electrodes is the appearance of a sharp rate maximum upon anodic current interruption which appears to be related to their dendritic structure and enhanced capacity for promoter storage.

The novel monolithic-type electrochemical promoted reactor (MEPR), filled with thick Rh and Pt coated films on thin yttria-stabilized zirconia (YSZ) plates, has been tested in simulated and real automotive exhaust gas. Ethylene oxidation and NO reduction by C2H4 in presence of oxygen were investigated in laboratory scale while the automotive bench testing was performed in the exhaust of a diesel engine. In all cases electropromotion was achieved, an advance which in addition to their compact and simple design, makes electropromoted units quite promising for automotive exhaust pollution control.

The concept of absolute electrode potential in aqueous and solid electrochemistry is discussed in light of the first experimental investigation utilizing a two Kelvin probe system which allows for direct in situ measurement of the work functions of both the, emersed or spillover modified, working and reference electrodes. In both cases, i.e. emersed electrodes in aqueous electrochemistry and spillover-modified electrodes in solid electrochemistry, it is found that the following two equations relate the working–reference electrode potential difference, U WR, and the work functions, ΦW and ΦR of the emersed or spillover-modified working and reference electrodes: $${eU_{\rm WR}=\Phi_{\rm W}-\Phi_{\rm R}}$$ $${e\Delta U_{\rm WR}=\Delta \Phi_{\rm W}}$$ where U WR is varied either by varying the gaseous composition or via a potentiostat. These equations show that the work function of emersed electrodes in aqueous electrochemistry or of spillover-modified electrodes in solid state electrochemistry is the natural choice of the absolute electrode potential: $${U_{\rm abs}=\Phi_{\rm W}/e}$$ The value $${{U_{{\rm H}_2}^{0}(\hbox{abs})=4.46\pm 0.15\,\hbox{V}}}$$ was obtained as the absolute potential value of the H2/H+ electrode in aqueous solutions at $${{p_{{\rm H}_2}=}1\,\hbox{bar}}$$ , pH = 0 and T = 298 K, while the value of $${{U_{{\rm O}_2}^{0}(\hbox{abs})=5.14\pm 0.05\,\hbox{V}}}$$ was measured as the absolute potential value of the O2/O2− electrode in YSZ (8 mol% Y2O3-stabilized-ZrO2) at $${{p_{{\rm O}_2}=1\,{\rm bar}}}$$ and T = 673 K.

The electrochemical promotion of catalysis (or NEMCA effect) was studied for the CO oxidation and water gas shift reaction on a Pt anode in a polymer electrolyte membrane (PEM) fuel cell. It was found that this phenomenon plays a significant role in a normal fuel cell operation (fuel mixture – air) but not in a hydrogen pumping operation (fuel mixture – H2). This implies that the role of oxygen crossover in the electropromotion (EP) of CO oxidation is vital. During fuel cell operation, the increase in the rate of CO consumption is 2.5 times larger than the electrochemical rate, I/2F of CO oxidation, while for oxygen bleeding conditions (fuel mixture + O2−air) the increase is five times larger than I/2F. This shows that the catalytic properties of the Pt anode are significantly modified by varying the catalyst potential. In order to confirm the role of oxygen crossover, Nafion membranes (117, 1135) with different thickness, were studied. The results show that upon decreasing the membrane thickness the crossover is increased and thus the electrochemical promotion effect becomes more pronounced.

The repulsive Coulombic forces exerted between proton wave particles in electrochemical and physical systems are examined, together with the attractive ion-induced dipole forces between protons and neighboring neutral particles, e.g. neutrons in the case of physical systems (nuclei). It is shown that when protons and neutrons are treated as harmonic oscillators with the same kinetic and potential energy, then two roots exist for their vibrational velocity. One root corresponds to negligible relativistic corrections ( v / c ≪ 1 ) and unstable nuclei, the other to significant relativistic corrections ( v / c ≈ 1 ) and to formation of stable nuclei. It is shown that the first root corresponds to protons in chemical–electrochemical systems and the second (relativistic) root corresponds to protons in nuclei. In the latter case the formation of stable nuclei is due to the attractive ion-induced dipole forces and to the pronounced increase in mass and gravitational forces. The latter, together with the ion-induced dipole forces, counterbalance the strong repulsive Coulombic forces. This leads to the analytical computation of the energy of formation of the 4 He and 2 H nuclei and of the gravitational constant. All three computed values are in quantitative agreement with experiment.

The role of the non-linear conductivity of fully hydrated Nafion membranes is discussed on the performance of state-of-the-art PEM fuel cells. It is shown that the Nafion conductivity contains two components, one constant corresponding to proton transport in the aqueous phase of the membrane, the other exponentially dependent on potential, linearly increasing with membrane thickness and strongly increasing with hydrogen partial pressure at the anode. A simple macroscopic mathematical model, accounting for the observed exponential dependence of Nafion conductivity on potential is developed and shown to provide a semiquantitative fit to the experimental I – U curves.

The effect of catalyst film thickness on the magnitude of the effect of electrochemical promotion of catalysis (EPOC or NEMCA effect) was investigated for the model catalytic reaction of C2H4 oxidation on porous Pt paste catalyst-electrodes deposited on YSZ. It was found that the catalytic rate enhancement ρ is up to 400 for thinner (0.2 μm) Pt films (40,000% rate enhancement) and gradually decreases to 50 for thicker (1 μm) films. The results are in good qualitative agreement with model predictions describing the diffusion and reaction of the backspillover O2− species which causes electrochemical promotion.

The effect of catalyst film thickness on the magnitude of the effect of electrochemical promotion was investigated for the model catalytic reaction of C2H4 oxidation on porous Pt paste catalyst-electrodes deposited on YSZ. It was found that the catalytic rate enhancement ρ is up to 400 for thinner (0.2 μm) Pt films (40,000% rate enhancement) and gradually decreases to 50 for thicker (1 μm) films. The Faradaic efficiency Λ was found to increase moderately with increasing film thickness and to be described semiquantitatively by the ratio 2Fr o/I 0, where r o is the unpromoted rate and I 0 is the exchange current of the catalyst–electrolyte interface. The results are in good qualitative agreement with model predictions describing the diffusion and reaction of the backspillover O2- species, which causes electrochemical promotion.

Proton migration through hydrated Nafion membranes in polymer electrolyte membrane (PEM) fuel cells occurs both in the aqueous phase of the membrane and on the sulfonate groups on the surface of the membrane pores. Here we show using D 2 and H 2 fuel and basic quantum mechanical equations that this surface proton migration is largely due to proton tunneling between adjacent sulfonate groups, leading to an exponential variation of Nafion conductivity with cell potential. This amphibious mode of proton migration, particle-like in the aqueous phase and wave-like in the narrow pores, is shown to be the major cause of cell overpotential, bistability and oscillations of state-of-the-art PEM fuel cells operating on H 2 , reformate or methanol fuel. We also show that this phenomenon can be exploited via introduction of a third auxiliary electrode to independently control the anode–cathode potential difference and dramatically enhance fuel cell power output even in absence of noble metals at the anode.

Recent progress is surveyed both in elucidating the mechanism of electrochemical promotion at the molecular level and in utilizing it in monolithic electropromoted catalytic reactors. On the mechanistic side, recent 18O2 TPD and 18O2 + CO TP reaction studies have confirmed, together with STM, the validity of the sacrificial promoter model for both electrochemical promotion and metal–support interactions of Pt and Rh with anionic (YSZ) and mixed anionic-electronic supports. On the practical side, two recent advances are discussed, i.e., the electropromotion of thin (40 nm) sputtered catalyst films, with metal dispersion of the order of 20%, and the development of the monolithic electropromoted reactor (MEPR) which is a hybrid between a monolithic catalytic reactor and a flat-plate solid oxide fuel cell and allows for compact design and easy scale-up and scale-down of electropromoted catalytic units.