The use of lithium intercalation electrodes (LIE) for recovering lithium from geothermal sources (containing <= 400 ppm of lithium) has the potential to revolutionize the lithium mining industry. This work proposes a conceptual scaled-up process for LIE, utilizing concentrated brine of 15 m3 h-1 (384.32 mM or 2,666 ppm of lithium) obtained from a reverse osmosis unit. Given the high lithium concentration in the concentrated brine, testing LIE performance under high lithium content conditions (1 M LiCl) is essential. In this study, LiMn2O4 supported on vitreous carbon foam is evaluated as the positive electrode. Degradation of the intercalation-active material, LiMn2O4, was observed in acidic media, with significant manganese dissolution. In contrast, at near neutral pH, dissolution rate is considered lower. Faradaic efficiency in acid media showed 98% efficiency only during the first potentiostatic deintercalation run. Subsequent runs exhibited non-faradaic behavior, which was also attributed to manganese dissolution. To develop strategies for mitigating LiMn2O4 degradation, equilibrium diagrams for the Li-Mn-H2O system (Poubaix Diagram) was constructed. In addition to propose a scaled-up process for lithium recovery from geothermal sources, this work investigates the performance of lithium intercalation under conditions relevant to large-scale operations.

Plasma water treatment has emerged as a powerful technology capable of abate perfluoroalkyl substances (PFAS) in water matrices. With the electrochemical configuration and cathodic polarity, the electrified plasma/liquid interface (EPLI) not only produces in-situ hydrated electrons ( ) that readily react with PFAS, but also produced radicals in the plasma effluent. This study uses chemical reaction networks (CRN) to investigate the chemical pathways of PFAS degradation by EPLI-induced , allowing for a direct comparison with the bench experiments of Stratton et al. (Environ. Sci. Technol. 2017, 51, 3, 1643) and Alam et al. (Chemical Engineering Journal, 2024, 489, 151349). The computational results indicate that Perfluorooctanoic Acid (PFOA) degradation by EPLI-induced has a Faradaic efficiency of less than 0.01% given the typically low concentration of PFOA in water matrices, meaning that the majority of engages with water reduction, generating gaseous hydrogen. EPLI-induced alone cannot account for the energy efficiency observed in bench experiment of Stratton et al. and Alam et al., suggesting the presence of other plasma-induced radicals. This work evaluates the gas-phase H radical as crucial for degrading PFOA at the gas/liquid interface, which is created by the plasma effluent in contact with the water matrix. This work paves the way for construct effective plasma-based industrial reactors to degrade PFAS, suggesting the formation of radical-H in the plasma effluent as a key parameter to be optimized.

Plasma electrochemistry has emerged as a powerful technology capable of producing radicals in a water matrix. In situ generation of hydrated electrons (), which can induce the formation of radicals like sulfate () and hydrogen () are important for oxidation of perfluoroalkyl substances (PFAS), a persistent pollutant. Building on the recently developed model for chemical dynamics induced by plasma electrochemistry [The Journal of Physical Chemistry C, 2019, Vol. 123 (36), 21896], this study sheds light on the formation and depletion dynamics of and from an empirical theoretical perspective. Our findings reveal that the local concentration of can reach 7.36 mM in acidified ultrapure water, enabling the degradation of 96 µM of PFAS, which is significantly higher than the highest reported occurrence in water bodies. Furthermore, the concentration of can reach 121,000 µM, which ideally enables the full oxidation of 6,310 µM of PFOS (1/19 parts of the maximum radical concentration). While these results demonstrate the promising potential of plasma electrochemistry for environmental remediation, further bench experiments are required to validate our empirical theoretical predictions and refine the mechanism of reactivity of these radicals. Overall, this study provides valuable insights into the use of plasma electrochemistry for the efficient removal of PFAS and other environmental pollutants.

The electrified plasma-liquid interface (EPLI) has two major local reactors, the plasma phase and the liquid phase. Both local reactors enable water splitting, but their synthesis mechanism is different. While the mechanism of H 2 synthesis in a liquid phase (plasma electrochemistry) was reasonably deciphered, the respective mechanism in the plasma phase does not (plasma chemistry). In this present contribution, the Chemical Reaction Network (CRN) analysis serves as a tool to decipher the H 2 synthesis mechanism in the plasma reactor. For that, the datum from the laboratory of Sankaran serves as grounds for the CNR analysis. Sankaran team identified that the equilibrium vapor pressure of water introduces water vapor in the plasma phase; and that, fundamentally, there were eight elementary reactions involved in the plasma-chemistry mechanism of H 2 synthesis, i.e. , those reactions containing the largest constant rates (or electron rate coefficients). [1] The authors obtained the reaction rate constants via a numerical solution of the Boltzmann equation (BE) for electrons in weakly ionized gases considering the uniform electrical field. [2] Together, those eight elementary reactions form the following global reaction for the water splitting via electron-impact 8 H 2 O → ●H+ ●OH + ●O + O – + O + + OH – + OH + + H – + H + that is also rationalized in terms of global CRN, shown in figure 1. The water molecule splits into two major classes of fragments, the radical fragment set {●H, ●OH and ●O} and the ionic fragment set {O – , O + , OH – , OH + , H – , H + }. These two classes of fragments receive different treatments in this work because their kinetic relaxation is supposed to follow different time scales. The radical fragment is supposed to relax toward final products much faster than the ionic fragments. For this reason, only the chemical dynamics of the radical fragment are considered in the relaxation step toward the final products. The chemical dynamics of relaxation toward final products, thus, take into account only the set of radical fragments. This talk will present and discuss the chemical reaction network (CRN) for the relaxation of the radical fragment toward final products like hydrogen (H 2 ), hydrogen peroxide (H 2 O 2 ), water (H 2 O), and eventually oxygen (O 2 ). The radical-relaxation CNR is not shown in this abstract but will be present/discussed in the talk. Roughly speaking, the radical-relaxation dynamics must deliver hydrogen as the major product and hydrogen peroxide as the major side-product, besides a stochiometric ratio of 4 to 1, respectively. Specifics on whether the radicals •OH relaxes toward H 2 O 2 or H 2 O depend on the local dynamics, meaning that it mostly relies on the parameter set values that drive the CRN. Unfortunately, there is no experimental evidence already reporting the stoichiometry of products, which makes it unfeasible to evaluate the adherence of our analysis to the experimental pieces of evidence. References [1] Toth, J.R., et al., On the Non-Faradaic Hydrogen Gas Evolution from Electrolytic Reactions at the Interface of a Cathodic Atmospheric-Pressure Microplasma and Liquid Water Surface. Journal of The Electrochemical Society, 2020. 167 (11): p. 116504.Society, 2020. 167 (11): p. 116504. [2] Hagelaar, G.J.M. and L.C. Pitchford, Solving the Boltzmann equation to obtain electron transport coefficients and rate coefficients for fluid models. Plasma Sources Science and Technology, 2005. 14 (4): p. 722-733. Figure 1 . Global chemical reaction network (CRN) for the water splitting due to the free-electron collision with the molecules of water vapor in the plasma phase formed in a noble-gas jet; such CRN also represents the global mechanism of hydrogen-radical formation, which is the key water-fragment allowing for the hydrogen synthesis in the plasma reactor. Figure 1

In the photochemical conversion of hydrogen peroxide (H 2 O 2 ) into radical ·OH, the rule of radiation dose (the quantum yield) on the oxidation kinetics is well known. In contrast, the H 2 O 2 dose mostly remains an attempt-and-error variable. Here, we propose a method to estimate the efficiency of H 2 O 2 dose consumption by the mineralization micro-kinetics that enables a generalist strategy for a more cost-effective dose of the oxidant. It needs the time-dependent H 2 O 2 , micropollutant, and product (CO 2 ) measure. Photo-Fenton (FP) hydrochlorothiazide (HCT) oxidation using a tubular photo-reactor and UVA radiation assisted in demonstrating the method. The average value of ~ 38% was on top of the best efficiencies associated with some of the fastest mineralization rates. Such efficiencies depend on the stochiometric concentration of the oxidant. Here, the variable stoichiometric H 2 O 2 excess for mineralization is proposed as a universal metric to quantify the (under-) over-dose of H 2 O 2 . Overall, H 2 O 2 excess between 2 and 5 leads to H 2 O 2 consumption efficiencies above 30%, together with a fast rate of CO 2 formation (mineralization). In contrast, any value below one invariably leads to a sluggish oxidation rate, leading even to the total depletion of the oxidant. Besides proposing a selection criterion for the most cost-effective H 2 O 2 -dose and providing some examples, this work carefully analyzes the commitment of the H 2 O 2 excess concerning the energy costs (EEO).

Hydrochlorothiazide (HCT) is a pharmaceutical micropollutant highly toxic to the environment, being absolutely necessary to oxidize it completely to CO2. Here, the variables stoichiometric H2O2 excess for (a) degradation and (b) mineralization are defined and used as metric to quantify the dosimetry of the H2O2. So that, dose of H2O2 qualifies being under- and over-dose respectively for values below and above such standards. In this work, these concepts have been elucidated across AOPs regarding the H2O2 degradation excess, whereas only UVC-Fenton was used regarding the H2O2 mineralization excess. At a H2O2 mineralization excess of 0.68 (equivalent to degradation excess of 36.74), oxidation via UVC-H2O2 enables absolute (100

The use of methane as the energy vector in our current energy matrix has challenged scientists to solve problems, which are now related to the exploration of oil wells but tomorrow will be the foundation for a carbon-neutral industry. Subsea exploration challenges engineers to find new solutions to separate CO2 from CH4 at the extremely high pressure of ca. 400 bar, to which all mature separation technologies are unsuitable. In this review, we highlight possible ways to employ ionic liquid (IL) as a highly selective absorbent to CO2 for extremely high pressure. Besides revising the high-pressure physical-chemical properties of ILs, the IL designing principles, and finally, the current employment of IL for preparing membranes, we prospect possible solutions for the sluggish, disfavored IL-regeneration at high pressure. We prospect-CO2 electro-reduction reaction (CO2RR) as a promising disruption for separation processes, being CO2RR-based technologies viable not only for IL-regeneration after the IL-based CO2 capture but also for CO2 conversion into valuable fuels/chemicals. As a prelude to CO2RR-based technologies, this review highlights key aspects concerning the use of IL as the electrolyte in an electrochemical cell performing CO2RR.

The electrified plasma/liquid interface (PLI) induces the CO2 reduction (CO2R) by mediation of the solvated electron. Recent theoretical analysis of the chemical reaction network (chemical mechanism) revealed a 100% faradaic efficiency for CO2R [1] provided that the liquid surface was a flowing electrolyte; however, the theoretical analysis did not consider the proton concentration as a chemical variable, or the pH of the electrolyte so to speak, disabling to predict the distribution of products over the entire acid scale. For this reason, in this work, the proton has been categorically considered as a reactant and an essential variable for the dynamical model describing the CO2R via electrified PLI.Two new routes toward formic acid production are proposed namely the disproportionation-like (via-2) and radical cross-combination (via-3) reactions, see figure 1. Both consume the radical H formed by the scavenging of the solvated electron by the proton. The computational results reasonably matched the concentration ratio formate to oxalate around 3.0 for pH 2.45, which features the physical experiments [2]. This ratio would represent 25% selectivity toward formate at pH 2.45 for a flowing-electrolyte experiment. With this reasonably assertive mechanism, it was possible to predict that, at the same conditions of flowing electrolyte, an extremely acid pH (~1) would increase the selectivity toward formate, between 46 and 90% repectivelly for via-2 and via-3. Fig 1. Chemical reaction networks are shown in the LHS, and the predictions on the concentration ratio oxalate to formate are shown in the RHS for each path of formate synthesis (via–3 and via–2) and both combined. References [1] A. Mota-Lima, J.Phys. Chem. C, 124, 10907(2020). [2] P. Rumbach, R. Xu, and D. B. Go, J. Electrochem. Soc., 163, F1157 (2016). Figure 1

The electrified plasma/liquid interface (PLI) serves as a unique electrosynthesis platform for the CO2 reduction reaction (CO2RR). This work aims to highlight the potential of such an electrosynthesis platform. For this reason, the CO2RR mechanism is postulated by considering the volume beneath the electrified PLI, termed the nanoreactor, and its chemical dynamics are evaluated by computational experiments. The commonalities noted between the reactant species in the electrified PLI and the field of radiolysis help to postulate the mechanism. The chemical dynamics not only explain the preferential synthesis of oxalate due to the promotion of a carbon-carbon bond by the high local concentration of the carboxyl radical anion (CO2-center dot(aq)) but also elucidate the depletion of the dissolved CO2(CO2(aq)) at the nanoreactor within the initial 0.043 s of continuous discharge, with hydrogen being produced only afterward. This work estimates ca. 98% CO2RR efficiency; of this, 97% is selective to oxalate if a flow cell is used as the electrolyte flow refills the CO2(aq) content into the nanoreactor. This study postulates a radiolysis-based mechanism for CO2RR via the electrified PLI, which provides insight in order to develop processes in the field of plasma electrochemistry.

The electrified plasma/liquid interface (PLI) promotes the CO2 reduction (CO2R) with a spectrum of products distinct from that of other electrochemical platforms. However, the lack of fundamental understanding greatly disables the preconize of its industrial potential. In particular, the inaccurate reaction mechanism of CO2R via electrified PLI brings imprecision on the theoretical predictions of selectivities in acid electrolytes. For this reason, the present work categorically considers the proton as a reactant and the proton concentration as an essential parameter for the dynamical model describing the CO2RR via electrified PLI. Two new routes toward formic acid production are proposed, namely, the disproportionation-like and radical cross-combination reactions. Both were capable of significantly reproducing the feature observed with real-life experiments for the final product proportions; however, the cross-combination reaction adjusts the most. With these reasonably assertive mechanisms of CO2RR in acid media, it was possible to predict that an extremely acid pH (~ 1) is required to attain concentration ratio oxalate to formate equal to 50 to 50 and 10 to 90 when considering the disproportionation-like and cross-combination reaction, respectively.

The current mechanism for the CO2 reduction reaction (CO2RR) via electrified plasma/liquid interface (electrochemical discharge) does not explain the favorable formic acid synthesis in aqueous acid media, bringing imprecision on the theoretical predictions of CO2RR selectivity in acid electrolytes. For this reason, this work proposes three CO2RR mechanisms toward formic acid, one of them being a long-stand established in the radiolysis field and passes to analyze the cases employing numerical simulation of their respective chemical dynamic models. With it, it is possible to identify two routes substantially contributing to the global formic acid production, namely the disproportionation-like and radical cross-combination reactions related to the last step. Despite studied here as two separate mechanisms, these two routes combined serve to propose an assertive mechanism of CO2RR in acid media.

Hydrochlorothiazide (HCT) is a pharmaceutical micropollutant highly toxic to theenvironment, being strictly mandatory to oxidize it completely toward CO2. In this context, howcould the HCT oxidation via advanced oxidative processes benefit from the accelerated oxidationrates promoted by the mineralization stoichiometric excess of H2O2 ? Overall, this workelucidates the role of stoichiometric H2O2 concentration on promoting fastdegradation/mineralization rates across Advanced Oxidative Processes (AOP). Employing 0.68excess of H2O2, it was found absolute (100%) HCT degradation within 60 minutes and 95%within 30 min for UVC-H2O2 oxidation; however, the mineralization of HCT suffered limitedoptimization even at high H2O2 excess, being at the best performance 26.76% HCT mineralizedvia UVC photo-Fenton within 60 min at initial 2.00 H2O2 excess. Very presumably, theevaporation of H2O2 was the underlying reason for a low mineralization performance. Togetherwith a detailed mathematical methodology, the time-synchronized evolution of both the residualH2O2 concentration and the TOC depletion were employed to infer the quantity of radical ∙OHthat effectively was consumed by the micropollutant mineralization. The global mean efficiencyof radicals •OH consumption by the HCT mineralization laid around 15% for UVC Fentonconsidering H2O2 excess of 2.00. Under these conditions, the residual H2O2 concentrationdepletes significantly within 30 minutes of UVC photo-Fenton oxidation, which indicates thateither the solution heating or stirring is very likely to promote a substantial loss of H2O2 byevaporation in the beaker-assembled reactor

Electrochemical discharger over liquid water enriched with dissolved carbon dioxide (CO 2 ) is capable of synthesizes formate (HCO 2 - ) and oxalate (C 2 O 4 2 - ), although in very low faradaic selectivity toward organic molecules ca. 9% [ 1 ]. The efficient CO 2 reduction (CO 2 -R) toward these organic molecules via electrochemical discharge remains a challenge. This contribution devotes to find possible ways to produce these products efficiently. In this context, the mechanism of electrosynthesis for both formate and oxalate is postulated and used from a theoretical perspective [ 2 ] to figure out which parameters are key to reach as maximum selectivity as possible. Figure 1a shows the chemical reaction network (CRN) postulated for CO 2 -R via electrochemical discharge over water. The discharge promotes a periodic perturbation on the local concentration of the solvated electron within the nanoreactor (volume of less than one nanoliter beneath the plasma liquid interface), firing the set of reaction displayed in this CRN. Three final products are formed, one volatile and two dissolved in the liquid phase. Gaseous hydrogen is a volatile product synthetized majorly via recombination of two solvated electrons, reaction (1); other two routes for hydrogen synthesis described in reference 2 are negligible over uninterrupted long lasting discharge. On the other hand, organic molecules requires the carboxyl radical anion {CO 2 -∙ (aq) } as precursor. In view of this CRN, the generalist model in reference (2) were used for implement the algorithm related to the chemical dynamical system. The computational experiments employed Wolfram language, 10 - 6 s step, a stationary current at level 9.5 mA (the same used by the researchers in ref 1) and the parameters displayed in table 1. The selectivity toward a given product is the ratio of its quantity of mole with respect to that of injected electrons. Figure 1b shows time evolution for the concentrations of the main reactants, the intermediate (carboxyl radical anion) and the final products. Figure 1c shows the selectivity toward each final product considering two span of continuous stationary discharge. The computational experiments demonstrated that the chemical dynamics driven by a stationary injection of electron (term qe in the model) in water is mostly governed by the formation reaction of CO 2 -∙ (aq) within the early 43 ms span of time. Within this period, full content of CO 2 in the nanoreactor depletes as result of the fastest reaction rate for the formation of CO 2 -∙ (aq) . The large local concentration (“local” qualifies the concentration inside the nanoreactor) of CO 2 -∙ (aq) favors the oxalate formation, being the oxalate the major final product. Formate is only synthetized at significant formation rate between 0.040 and 0.043 s, when the concentration of both solvated electrons and CO 2 -∙ (aq) start to be less dissimilar as consequence of the depletions of the aqueous CO 2 in the nanoreactor. Anytime thereafter, the solvated electrons has increased concentration, and the hydrogen passes to form majorly. Considering the 300,000 s (5 minutes used in reference 1), about 7.72% faradaic efficiency toward organic molecules is obtained, corroborating the low efficiency for experiments in real life. In conclusion, this work postulate the mechanism of CO 2 reduction via electrochemical discharge, and it suggests the employment of short span of stationary discharge to obtain faradaic efficiency toward organic molecules of 98.46%, being 96.89% selective toward oxalate. Figure 1 : (a) postulated chemical reaction network for CO 2 -R via electrochemical discharge over water, (b) time evolutions for the concentrations of either reactants or products , and (c) selectivity toward formate (yellow), oxalate (orange) and hydrogen (pink) at STP CO 2 saturation. Table 1 : parameters for solving the dynamical model [ 3 ] Parameter Value Unit Ref k1 6.0×10 9 L mol −1 s −1 3 k2 9.0×10 9 L mol −1 s −1 3 k3 1.0×10 10 L mol −1 s −1 3 k4 1.26×10 9 L mol −1 s −1 3 q e (9.5 mA) 98.46×10 -9 mol s - 1 1 V 2.36×10 -9 L 2 [H+] 0 1.00×10 -7 mol L -1 [CO 2 ] 0 40.00×10 -3 mol L -1 References [1]Rumbach, P., R. Xu, and D.B. Go, Electrochemical Production of Oxalate and Formate from CO2 by Solvated Electrons Produced Using an Atmospheric-Pressure Plasma. Journal of The Electrochemical Society, 2016. 163 (10): p. F1157-F1161. [2] Mota-Lima, A., et al., Electrosynthesis via Plasma Electrochemistry: Generalist Dynamical Model To Explain Hydrogen Production Induced by a Discharge over Water. The Journal of Physical Chemistry C, 2019. 123 (36): p. 21896-21912. [3] Neta, P., J. Grodkowski, and A.B. Ross, Rate Constants for Reactions of Aliphatic Carbon‐Centered Radicals in Aqueous Solution. Journal of Physical and Chemical Reference Data, 1996. 25 (3): p. 709-1050. Figure 1

Electrosynthesis via electrochemical plasma, a discharge over the surface of liquid water (or plasma cathode), may offer an unprecedented route of synthesis for chemicals and (wind) solar fuels. Describing the physical chemical events underneath plasma/liquid interface (PLI) on a theoretical basis is crucial for enabling a rational designing of chemical synthesis. To address this problem, this work proposes a generalist dynamical model for the nanoreactor, a fraction of nanoliters localized beneath the PLI that features substantially high concentration of hydrated electrons (e(aq)(-)), and it screens chemical reaction networks (CRN) related to the synthesis of hydrogen, a model electrosynthesis process. The computational results elucidate two major routes for hydrogen production: (a) in very alkaline media, the water reduction via self-recombination of eaq- [2e(aq)(-) + 2H(2)O -> H-2 + 2OH(-)] consumes the majority of e(aq)(-), whereas (b) in very acid media, e(aq)(-) is majorly scavenger by the ion H-aq(+), generating an abnormally high concentration of the radical H center dot,a precursor for gaseous hydrogen. Additionally, two scenarios are disadvantageous for synthesizing H-2. Side reactions with aqueous oxygen and aqueous radical center dot OH leads to substantial production of O-2(-) and OH-, respectively. Without loss of generality, the dynamical model proposed in this work is a powerful theoretical frame for understanding and predicting a variety of plasma-induced CRNs, assisting to advance the emerging field of plasma electrochemistry.

Reduction of silver cations followed by nanoparticle (Ag-NPs) synthesis is a model process to understand the reduction mechanism induced by a discharge over an aqueous surface, termed electrochemical plasma. This work aims at studying the silver reduction reaction steered by electrochemical plasma in the presence of other chemically active plasma-related interfaces, namely the plasma-gas and the liquid-gas interfaces. As no other plasma-induced species are able to reduce silver cations, the reduction of silver cations is employed as strategy to selectively detect the presence of hydrated electrons (e(h)(-)). The results demonstrate that the global rise of pH (increase in the content of OH-), observed for discharge in the helium gas phase, occurs in connection with the silver reduction, which is interpreted as a vivid experimental evidence of the second-order recombination reaction of the e(h)(-) (2e(aq)(-) + 2H(2)O -> H-2 + 2OH(-)). On the other hand, the global decrease of pH (increase in the content of H+) observed for discharge in mixed oxygen and nitrogen gas phase, is an event primarily driven by the Birkeland-Eyde process, and it is concomitant but spatially distinct from the electron injection. The acidification interferes in the NP formation, as NPs promptly dissolve in presence of HNO3. Only in complete suppression of the acidification, an experimental evidence of the reaction pathways for hydrated electron could be captured: e(h)(-) is competitively consumed through a scavenger-like reaction (reduction of silver cations in this work) and through the second-order recombination reactions of the e(h)(-). The kinetic model proposed in this work further corroborates this interpretation.

Acetylsalicylic acid (ASA) is a model pollutant and a representative of the emerging pharmaceutical micro-pollutants whose mineralization across several advanced oxidative processes takes hours to complete. This work devotes to optimize and understand the kinetic conditions to mineralize ASA using Photo-Fenton process with UVA radiation in a tubular photochemical reactor. The optimization employs a statistical tool termed factorial design (FD) that studies how the concentrations of ASA, Fe2+ and H2O2 affects the mineralization over a larger interval of concentrations. The factorial design indicates that the initial concentration of H2O2 is a crucial variable to achieve a fast rate of ASA mineralization. Using optimized contents of both H2O2 and Fe2+ (45 Mm and 1.5 mM, respectively) in the Photo-Fenton process (H2O2/Fe2+/UVA), mineralization around 90% is reached in about 10 min, the fastest rate ever observed, enabling to treat 0.012 m(3) h(-1) per tubular reactor. The underlying reason for such outstanding performance is attributed to the optimized 4.5-folds excess of [H2O2], i.e. the ratio of H2O2 concentration used at the initial time to that required for complete mineralization of the theoretic TOC. Measurements of the remaining concentration of H2O2 strongly indicates that excess of [H2O2] optimizes the instantaneous concentration of radical (OH)-O-center dot. As a conclusion, the stoichiometric excess of [H2O2] is an important parameter to be optimized for achieving the highest degree of mineralization at the shortest time when using the photochemical reactor, in turn, decreasing costs related to the total energy consumed both by the lamp and by the recirculation pump.

The turnover frequency (TOF) is conventionally used to measure activity in catalysis but is rarely used in electro-catalysis, which uses the value of the interfacial current instead. Herein, a procedure to quantify the TOF for the ethanol oxidation reaction (EOR) in electro-catalysis is proposed and compared with the value observed in catalysis (Sapi et. al., Nano Lett., 14 (2014) 6727). The intrinsic TOF in an alkaline medium is 9.23 molecules site(-1).s(-1), which is three times larger than the value obtained in an acidic medium, explaining the major differences observed between the interfacial currents recorded during cyclic voltammetry and chronoamperometry in the two media. In the future this methodology will be extended to single crystal surfaces and nanoparticles, assisting the development of electro-catalysts on a more fundamental theoretical basis.

Despite the net energy yield be the primary goal of ethanol electro-oxidation reaction (EOR), it is never measured in fundamental electrochemical studies. By combining galvanodynamic and potentiodynamic profiles of the steady states of the system, we demonstrate a methodology to estimate the dissipation of chemical energy that allows the inference of the fuel cell power output in relative terms. Apart from the empirical energy dissipation, several kinetic information are unravelled: (a) the kinetics is governed by ethanol adsorption rate for both media and for both external control modes; and (b) either the maximum current sustained by EOR or the steady state currents are, in addition, governed by a global coverage of poisonings species, which includes the contributions from COad and non-reactive OHad. The blocking effect of potassium cations over EOR is clearly verified, reducing the maximum activity up to a factor of 0.19, which is interpreted as an effect of the high coverage of non-reactive OHad. Finally, it is expected a slightly improvement of the power output of a direct ethanol fuel cell operating at steady state in alkaline media due to the lower chemical dissipation at fixed interfacial current value. Nonetheless, the blocking effect of potassium in alkaline media may, depending on the concentration, either induces an oscillatory regime at higher overvoltage (above 0.57 V) along with the preservation of the energy generation at lower overvoltage or completely decrease the energy generation due to a drastic loss of energy used to polarize the EOR. (c) 2018 Published by Elsevier Ltd.