Yang Shao‐Horn

Ion solvation in battery electrolytes involves supramolecular host–guest interactions and is most often enabled by Lewis basic coordination of cations, sometimes at the expense of cation mobility. Here, we investigate anion-centered solvation using Lewis acidic supramolecular hosts. We introduce a class of small-molecule boranes that selectively coordinate anions, enabling systematic interrogation of how anion binding strength governs salt dissociation and ion transport. A family of readily accessible boranes spanning a wide range of Lewis acidities was synthesized and evaluated with Li- and Na-based salts. Increasing borane Lewis acidity strongly correlated with enhanced dissociation and ionic conductivity of otherwise poorly soluble halide salts (Cl –, F – ), yielding order-of-magnitude conductivity enhancements and, in some cases, performance exceeding that of TFSI-based electrolytes. These results establish anion coordination strength as a powerful and tunable handle for regulating ion transport and expand supramolecular host–guest chemistry to the rational design of electrolyte solvation environments.

Statistical source data of Raman spectra, LSV, and SEI intensities Statistical source data of Raman spectra, potential, SEI intensities, and FE(NH3) Statistical source data of Raman spectra, potential, SEI intensities, and FE(NH3) Statistical source data of Raman spectra, perchlorate/solvent peak analysis, and SEI intensities Statistical source data of potential, FE(NH3), yield rates, Raman spectra, SEI composition Statistical source data of potential, FE(NH3), yield rates, SEI composition, evolution of potential/FE(NH3) with SEI composition

Statistical source data of Raman spectra, LSV, and SEI intensities Statistical source data of Raman spectra, potential, SEI intensities, and FE(NH3) Statistical source data of Raman spectra, potential, SEI intensities, and FE(NH3) Statistical source data of Raman spectra, perchlorate/solvent peak analysis, and SEI intensities Statistical source data of potential, FE(NH3), yield rates, Raman spectra, SEI composition Statistical source data of potential, FE(NH3), yield rates, SEI composition, evolution of potential/FE(NH3) with SEI composition

Abstract perando spectroscopy is a powerful tool that enables mechanistic understanding of materials but often requires advanced and expensive characterization tools. Infrared spectroscopy (IR) can directly probe bond-specific changes during electrochemical reactions using widely available instrumentation. Nevertheless, operando IR remains underutilized due to complex interpretation and the lack of commercial characterization setups. In this tutorial, we aim to offer basic guidance to non-specialists interested in the use of operando IR for the investigation of energy-related materials. This tutorial covers basic experimental design, cell setup, data treatment and interpretation, as well as more advanced IR techniques such as synchrotron-based IR (SR-IR) and surface-enhanced IR absorption spectroscopy (SEIRAS). Examples from different electrochemical applications, ranging from batteries to electrocatalysts, are provided for illustration. 
Current literature offers a broad range of operando cell setups suitable for different electrochemical conditions and applications. Operando spectro-electrochemical cells are typically customized in-house, and their electrochemical performance must be carefully cross-checked with conventional cells to detect potential side reactions caused by cell modification. After measuring experimental spectra, subtraction or multivariate analysis can be used to resolve features and identify relevant IR-active changes. Assigning IR bands and understanding mechanisms can be facilitated by computational modeling, which assists in interpreting results by calculating IR spectra of different species when experimental reference spectra are difficult to measure. Improved data treatment and modeling enhance the analytical power of operando IR spectroscopy and make it more user-friendly. The concurrent development of spatially resolved and optic fiber IR spectroscopy, as well as the combination of IR with other developing non-linear spectroscopies offer exciting opportunities for the future of this technique.

Sodium/chlorine and lithium/chlorine batteries are new types of high-voltage and -capacity batteries reported recently with great potential to be developed into high-energy-density batteries for real-world applications. In this work, we report using cobalt polyphthalocyanine grown on multiwalled carbon nanotubes as the positive electrode in both sodium/chlorine and lithium/chlorine batteries to achieve, for the first time, a stable cycling capacity well exceeding the first discharge capacity in chlorine batteries. We employed various techniques together with theoretical calculations to reveal that cobalt polyphthalocyanine not only facilitates the formation of submicron-sized sodium chloride crystals with excellent electrochemical activity, but also enhances the reversibility of chlorine/chloride redox by forming cobalt–chlorine and sodium–nitrogen bonds during battery cycling. Additionally, cobalt polyphthalocyanine acts as a good storage medium for the chlorine that is formed during battery charging. We also discovered that the metal center can be changed from cobalt to iron and the carbon substrate can be varied from multiwalled carbon nanotubes to graphite for both sodium/chlorine and lithium/chlorine batteries. The chlorine batteries can now operate using only a minimal amount of electrolyte, and we were able to construct a sodium/chlorine battery with ∼150 Wh kg –1 or ∼325 Wh L –1 full-cell energy density for the first time.

Sodium/chlorine and lithium/chlorine batteries are new types of high-voltage and -capacity batteries reported recently with great potential to be developed into high-energy-density batteries for real-world applications. In this work, we report using cobalt polyphthalocyanine grown on multiwalled carbon nanotubes as the positive electrode in both sodium/chlorine and lithium/chlorine batteries to achieve, for the first time, a stable cycling capacity well exceeding the first discharge capacity in chlorine batteries. We employed various techniques together with theoretical calculations to reveal that cobalt polyphthalocyanine not only facilitates the formation of submicron-sized sodium chloride crystals with excellent electrochemical activity, but also enhances the reversibility of chlorine/chloride redox by forming cobalt–chlorine and sodium–nitrogen bonds during battery cycling. Additionally, cobalt polyphthalocyanine acts as a good storage medium for the chlorine that is formed during battery charging. We also discovered that the metal center can be changed from cobalt to iron and the carbon substrate can be varied from multiwalled carbon nanotubes to graphite for both sodium/chlorine and lithium/chlorine batteries. The chlorine batteries can now operate using only a minimal amount of electrolyte, and we were able to construct a sodium/chlorine battery with ∼150 Wh kg^–1 or ∼325 Wh L^–1 full-cell energy density for the first time.

Per- and polyfluoroalkyl substances (PFAS) are persistent pollutants that are resistant to conventional water treatment. This study investigates the electrochemical degradation of perfluorooctanoic acid (PFOA) in perchlorate and sulfate electrolytes with boron-doped diamond. Quantification of PFOA degradation and fluoride (F – ) and short-chain perfluorocarboxylic acid (PFCA) formation showed similar defluorination efficiency in both electrolytes at 4.0 V RHE but significantly higher PFCA yields with the sulfate electrolyte. Through electrochemistry-mass spectrometry, 19 F and 1 H NMR spectroscopy, potential-dependent investigation, and radical-scavenger experiments, we showed that both electrolytes exhibit similar decarboxylation rates of the carboxylic group to evolve CO 2 . However, HO • primarily drove C–F cleavage, releasing F – and leaving the remaining fluorocarbon backbone hydrogenated, while SO 4 •– promoted C–C cleavage to form fully fluorinated shorter-chain PFCAs. These results highlight the distinct roles of free radicals in PFOA degradation, offering mechanistic insights to design electrolytes to promote complete PFAS defluorination and suppress the formation of short-chain PFAS.

Achieving reversible sodium metal plating and stripping is essential for enabling practical Na metal batteries but remains limited by unstable electrolyte–metal interphases. Here, we quantitatively examine how solvation thermodynamics, interfacial kinetics, ion transport, and solid electrolyte interphase (SEI) composition govern Na metal reversibility in sodium bis(fluorosulfonyl)imide (NaFSI) electrolytes with 1,2-dimethoxyethane (DME), fluoroethylene carbonate (FEC), and N,N-dimethylsulfamoyl fluoride (DMFSA). Unlike Li systems, Na metal Coulombic efficiency (CE) shows no correlation with either the Na + /Na redox potential or the interfacial reaction entropy. Instead, increased CE in electrolytes like 1 M sodium hexafluorophosphate in DME corresponds to faster interfacial kinetics relative to ion diffusivity ( j 0 SEI / FcD ). X-ray photoelectron spectroscopy highlights the importance of balancing the inorganic and organic SEI phases to optimize interfacial kinetics and CE. These results establish interfacial kinetics, rather than solvation thermodynamics, as a governing descriptor of Na metal reversibility, providing an electrolyte design framework for improving Na metal batteries.

Unlocking lithium metal batteries requires a robust solid electrolyte interphase (SEI) capable of sustaining high Coulombic efficiency (CE). Here, we develop in situ Fourier transform infrared (FTIR) spectroscopy to directly probe potential- and cycling-dependent formation of an organic SEI in carbonate electrolytes containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) and systematically correlate interfacial chemistry with CE. In 1.2 M LiPF 6 EC, an organic-dominated SEI comprising lithium ethylene dicarbonate (LEDC) forms starting at pre-plating potentials, yielding the highest CE (∼90%). In contrast, 1.0 M LiPF 6 EMC produces primarily soluble lithium ethyl carbonate (LEC) and develops a thick, LiF- and Li 2 O-rich, spatially heterogeneous SEI with poor reversibility (<15% CE). LP57 exhibits intermediate behavior, where the emergence of alternative semi-carbonates due to trace water destabilizes the organic SEI. Such observations demonstrate that an inorganic-dominated SEI does not intrinsically ensure high CE and instead highlight organic, LEDC-based interphases as critical to stable cycling.

Cross-institutional investigation of electrochemical glycine and amino acid oxidation to unveil conversion pathways and mechanistic implications relevant to ammonia recovery from organic waste.

The oxygen evolution reaction (OER) is crucial for electrofuel production. Metal–hydroxide organic frameworks (MHOFs), a subset of metal–organic frameworks with oxyhydroxide-like layers interconnected via organic linkers, have shown great promise as OER electrocatalysts. This study investigates lattice oxygen exchange in four Ni- and Fe-substituted MHOFs with varying linker stabilities using 18 O isotope labeling combined with operando Raman spectroscopy. A negative correlation between 18 O/ 16 O lattice oxygen exchange and the OER activity is shown, with Fe ions further suppressing exchange. Operando X-ray spectroscopy (XAS) and UV–vis further reveals that lattice oxygen exchange primarily proceeds on reduced Ni 2+ sites, with higher linker stability preserving more Ni 2+ sites and promoting greater lattice oxygen exchange. Supported by density functional theory, the MHOF surface transforms into an OER-active MO x H y -like phase, explaining the negative correlation of lattice exchange with the OER activity. This work also identifies a noninnocent role of the Raman laser in inducing lattice oxygen exchange and offers critical insights into various lattice oxygen exchange pathways in MHOFs, demonstrating their distinction from the catalytic lattice oxygen evolution reaction mechanism.

Iridium oxides (IrO 2 ) are of significant interest for low-temperature oxidation of small molecules such as CH 4 and CH 3 OH, although the physical origin of their high activity remains under debate. Here, we demonstrate that the enhanced activity of IrO 2 arises from the formation of coordinatively unsaturated (CUS) oxygen species. By combining ambient-pressure X-ray spectroscopy and density functional theory calculations, we present evidence for the formation of CUS oxygen during CH 4 and CH 3 OH oxidation. Such surface speciation correlates with the conversion of methane to carbon dioxide and methanol to methyl formate on rutile IrO 2 and hydrous IrO 2 powder catalysts in a plug-flow reactor at room temperature. These findings extend the understanding of the physical origin of the higher activity of iridium oxide thin-film catalysts to powder catalysts and provide insights into the tuneability of iridium-oxide-containing catalysts for low-temperature C–H and O–H bond activation.

Abstract While interfacial processes can dominate the internal resistance in solid‐state batteries, the (electro‐)chemical reactions occurring at the lithium│polymer interface are complex and dynamic upon cycling. A central factor for evaluating such reactions is the exchange current density j 0 that characterizes the kinetics of the interfacial charge transfer. However, its determination is challenging due to superimposed impedance contributions from the solid electrolyte interphase and interfacial charge transfer reactions. Moreover, different methodologies for determining j 0 can lead to different j 0 values. Herein, a carefully validated method to determine j 0 for polymer electrolytes is reported, using the example of polyethylene oxide‐based systems, by combining electrochemical impedance spectroscopy, Bayesian inference analysis, and distribution of relaxation times analysis. These impedance‐based methodologies are validated via the determination of j 0 using DC polarization measurements that are fit to a modified Butler–Volmer model, enabling the reliable determination of j 0 for polymer electrolytes and, thus, the analysis of the interfacial processes and reactions occurring in such systems.

High Resolution Image Download MS PowerPoint Slide Despite the ubiquity of the well-known phosphorus polyanion phosphite ( HPO 3 2 − ), it appears to be the case that no simple salt of the corresponding conjugate base ( PO 3 3 −, “ortho-phosphite”) has ever been reported. We report the synthesis and characterization of this elusive species as a major component of a mixture obtained upon mechanochemical reduction of condensed phosphates, as evidenced by solid-state 31 P NMR and Raman spectroscopy as well as subsequent reactivity studies. To corroborate the 31 P NMR spectroscopic assignment, we independently generated Na 3 PO 3 and K 3 PO 3 by deprotonation of Na 2 HPO 3 with NaCH 2 SiMe 3 and of K 2 HPO 3 with KCH 2 Ph, respectively, providing an orthogonal route to PO 3 3 − salts whose spectroscopic signatures match those observed in the mixture obtained by mechanochemical reduction. We further found that ortho-phosphite can act as a precursor for various phosphorus chemicals, such as P(OSiMe 3 ) 3 (46%), which is already well established as a precursor to a plethora of useful organophosphorus compounds. Therefore, our results not only establish the first formal pathway from P(V) phosphate starting materials to P(OSiMe 3 ) 3 without the intermediacy of white phosphorus, but also open the door to a broad range of downstream transformations based on this sustainable pathway. Additionally, BaHPO 3 ·H 2 O (66%), OP(OMe) 2 Me (DMMP), and OP(OBn) 2 Bn (DBBP) have been generated directly from ortho-phosphite, all traditionally synthesized from white phosphorus.

Sodium-metal batteries are a promising alternative to lithium-based systems for both transportation and large-scale energy storage. They offer a cost-effective, high-energy solution due to the abundance, lower cost, and reduced toxicity of their raw materials (e.g., sodium, and cobalt-free) [1]. However, the practical viability of conventional electrolytes with sodium-metal anodes and high-voltage cathodes remains limited. Their poor electrode-electrolyte interfacial stability and low ionic conductivities lead to electrolyte decomposition, dendrite growth, and low cycling stability, ultimately reducing capacity retention and power density [2], [3]. Despite significant research efforts over the past decade, the slow discovery speed of conventional trial-and-error approaches makes it challenging to identify promising new electrolytes that meet the demands of the rapidly expanding battery market, limiting innovation and scalability. In this work, we establish an active learning workflow to accelerate the discovery of new electrolytes, applicable to both liquid and polymer electrolytes [4], [5]. We develop a high-throughput experimental platform to systematically formulate and screen new non-aqueous sodium electrolytes. We explore a chemical space larger than 1.5 x 10 9 possible compositions —comprising 11 organic solvents, 5 sodium salts, extended solvent and salt ratios, and 15 total salt concentrations. We assess the ionic conductivity and solubility of all combinations in tandem, generating the first high-quality, unified reference library of sodium-based electrolytes. The discovery speed increased by a factor of 100. For instance, in less than 1.5 months, 168 unique electrolyte formulations were obtained. By simultaneously targeting specific measurements of coulombic efficiency in high-conductivity samples, we identify several promising formulations, exceeding 11 mS cm -1 , along with high coulombic efficiency and high-voltage stability. The generated database was then used to train a machine learning model, enabling predictive selection of the next iteration of electrolyte formulations while progressively narrowing the explored chemical space. We demonstrate that by integrating our high-throughput platform with data-driven methodologies and targeted experiments, electrolyte discovery can be expedited, guiding new strategies for the design of future electrolytes for sodium-metal batteries. References [1] C. Vaalma, D. Buchholz, M. Weil, and S. Passerini, “A cost and resource analysis of sodium-ion batteries,” Nat. Rev. Mater., vol. 3, no. 4, p. 18013, Mar. 2018, doi: 10.1038/natrevmats.2018.13. [2] Y. Zhao, K. R. Adair, and X. Sun, “Recent developments and insights into the understanding of Na metal anodes for Na-metal batteries,” Energy Environ. Sci., vol. 11, no. 10, pp. 2673–2695, 2018, doi: 10.1039/C8EE01373J. [3] Y. Wang et al., “Developments and Perspectives on Emerging High-Energy-Density Sodium-Metal Batteries,” Chem, vol. 5, no. 10, pp. 2547–2570, Oct. 2019, doi: 10.1016/j.chempr.2019.05.026. [4] M. A. Stolberg et al., “A Data-Driven Platform for Automated Characterization of Polymer Electrolytes,” Dec. 23, 2024. doi: 10.26434/chemrxiv-2024-gpmm7. [5] J. Peng et al., “Human- and machine-centred designs of molecules and materials for sustainability and decarbonization,” Nat. Rev. Mater., vol. 7, no. 12, pp. 991–1009, Aug. 2022, doi: 10.1038/s41578-022-00466-5. Acknowledgments This work was supported by the Breakthrough Energy Explorer Grant. The authors also acknowledge the financial support from the MIT Postdoctoral Fellowship Program for Engineering Excellence.

Sodium-based batteries are a promising, sustainable alternative to lithium-based batteries due to the high abundance and low cost of sodium resources, providing an attractive pathway to large-scale grid energy storage. While significant advances have been made in the development of high-performance cathode materials, the electrolyte remains the critical limitation for the practical viability of high energy density Na-metal batteries. Conventional sodium liquid electrolytes form poor electrode-electrolyte interfaces due to the high reactivity of Na metal, causing continuous electrolyte decomposition that results in uncontrolled solid electrolyte interphase (SEI) growth, Na dendrite formation, poor Coulombic efficiencies (CE), and irreversible capacity loss. This study will examine the role of thermodynamics and kinetics of electrolytes on the reversibility of Na metal stripping and plating. From the thermodynamic standpoint, we will investigate the salt- and solvent-dependent Na + solvation free energy by measuring the Na + /Na redox potential, the bulk entropy, and the interfacial reaction entropy of electrolytes consisting of salts with different dissociation energies and solvents with different donor numbers. From the kinetics perspective, we aim to probe the diffusivity of Na + ions in bulk electrolytes and the exchange current density of Na stripping and plating through the SEI. We seek to correlate the thermodynamic and kinetic parameters with the Coulombic efficiencies of different electrolytes in order to reveal how the interplay of these effects can serve as descriptors for Na metal reversibility, which will guide the design of high-performing liquid electrolytes for practical Na metal batteries.

Understanding ion transport in polymer electrolytes is critical for designing next-generation energy storage systems. Molecular dynamics simulations offer complete atomistic information, but disentangling the contributions of distinct diffusion modes in cation transport remains a challenge. Here, we introduce a mathematical algorithm that decomposes the transport coefficient into a sum of interpretable diffusion mechanisms based on changes in local atomic environment. Applying this framework to a prototypical polymer electrolyte, we quantify the contributions of proposed transport modes. We identify a rare lithium diffusion mechanism associated with the disassembly of existing solvation environments which contributes an order of magnitude more to lithium transport properties per event than all other mechanisms. Finally, we characterize the spectrum of microscopic diffusion events, providing a detailed and quantitative understanding of ion transport in polymer electrolytes. Our approach offers a promising path toward a more quantitative and mechanistic understanding of ion transport in soft matter electrolytes.

The underlying reaction mechanism in lithium-ion batteries remains poorly understood. We provide experimental and theoretical evidence that lithium intercalation occurs by coupled ion-electron transfer, where ion transfer across the electrode-electrolyte interface is facilitated by electron transfer to a neighboring redox site. Electrochemical measurements for a variety of common electrode and electrolyte materials reveal a universal dependence of the (de-)intercalation rate on Li + vacancy fraction, as well as temperature and electrolyte effects consistent with the theory, which could be used to guide the molecular design of lithium-ion battery interfaces.

Solid polymer electrolytes are a promising class of materials to enable next-generation Li-based batteries. They offer highly tunable properties, scalable processing conditions, and increased safety. However, current solid polymer electrolytes do not have sufficient ionic conductivity for room-temperature battery applications. The discovery of novel polymers and the optimization of polymer-salt formulations with high ionic conductivity are critical bottlenecks in developing new polymer-based batteries. Programmable laboratories driven by machine learning algorithms have been proposed to power accelerated discovery cycles. Here we demonstrate a closed-loop, machine-learning driven Bayesian optimization pipeline for optimizing a dry polymer electrolyte composed of poly(ϵ-caprolactone) (PCL) electrolyte with one of 18 lithium salts. We use previously collected literature data to warm-start our optimization and achieve high performance while following through with a novel high-exploration batch-based sampling method. Formulations chosen by the sampling method were mixed, cast, dried, and characterized on an autonomous high-throughput polymer electrolyte platform. After five batches of optimization conducted in just over a month, we discovered formulations with ionic conductivity that were on par with top-performing poly(ethylene oxide) electrolytes, the standard of the field.

To achieve a sustainable future, the electrification of the chemical manufacturing industry is crucial. The electrochemical CO 2 reduction reaction (CO 2 RR) offers a promising pathway to produce value-added chemicals and fuels, including methanol─a key chemical building block and energy carrier. This approach presents a carbon-neutral alternative to conventional, fossil fuel-based methanol production. However, replacing well-established thermochemical processes and achieving cost-competitive production requires the development of highly efficient and selective catalysts for CO 2 -to-methanol conversion, as well as systematic device-level optimization. In this Perspective, we discuss the potential of methanol production via CO 2 RR and provide an overview of recent advances in catalyst development. We also propose experimental protocols for methanol quantification, emphasizing the critical need for rigorous evaluation of catalysts to ensure the validity and reproducibility of results, and demonstrating boron phosphide as an irreproducible case. We review seminal studies on CO 2 RR by cobalt phthalocyanine to make methanol, and current understanding of the reaction mechanistic details. Lastly, we discuss the challenges associated with its translation into practical devices and outline future research opportunities to advance electrochemical CO 2 RR for methanol production at scale.

Understanding ion transport in polymer electrolytes is critical for designing next-generation energy storage systems. Molecular dynamics simulations offer complete atomistic information, but disentangling the contributions of distinct diffusion modes in cation transport remains a challenge. Here, we introduce a mathematical algorithm that decomposes the transport coefficient into a sum of interpretable diffusion mechanisms based on changes in local atomic environment. Applying this framework to a prototypical polymer electrolyte, we quantify the contributions of proposed transport modes. We identify a rare lithium diffusion mechanism associated with the disassembly of existing solvation environments which contributes an order of magnitude more to lithium transport properties per event than all other mechanisms. Finally, we characterize the spectrum of microscopic diffusion events, providing a detailed and quantitative understanding of ion transport in polymer electrolytes. Our approach offers a promising path toward a more quantitative and mechanistic understanding of ion transport in soft matter electrolytes.

Developing efficient and durable catalysts for the alkaline oxygen evolution reaction (OER) is vital to achieving practical anion-exchange membrane water electrolyzers (AEMWEs) for green hydrogen production. Here, we break the activity–stability trade-off of electrocatalysis by defect engineering of Ni-based metal–organic electrocatalysts (Ni-benzenedicarboxylate; Ni-BDC) through coordinating ferrocenecarboxylates (Fc) to the metal sites. Experimental results collectively reveal that the defect MOF (Ni-BDC:Fc_5:1) exhibits a high OER turnover frequency of 0.75 O 2 s –1 at 300 mV overpotential. Operando Raman spectroscopy and isotope-labeling electrochemical mass spectrometry measurements indicate the structure of Ni-BDC:Fc_5:1 is also more stable in service than that of pure Ni-BDC. The high activity and stability could be attributed to the moderate defects (i.e., unsaturated Ni sites) in the structure that not only increase the intrinsic activity and stability of the local active environment by inhibiting lattice oxygen exchange but also electrochemically activate the bulk of the catalysts by creating a porous network that facilitates internal H 2 O/OH – conduction with enhanced electronic conduction. Accordingly, an AEMWE employing Ni-BDC:Fc_5:1 as the OER catalyst delivers an industrial-level current density of 1 A cm –2 at 1.73 V cell and can be steadily operated for more than 120 h.

Methanol is a promising hydrogen carrier and clean fuel, particularly when synthesized from green hydrogen and captured CO2. Its oxidation reaction is a key half-cell process in both electrochemical reforming for hydrogen and direct methanol fuel cells (DMFCs). Traditionally, methanol oxidation on Pt catalysts is understood to proceed via dual pathways: an indirect route involving *CO intermediates and a direct route producing soluble species such as formaldehyde and formate. However, our 18O isotope labeling experiments with H218O and CH318OH have, for the first time, revealed that a majority proportion of methanol-derived oxygen does not appear in the final products, especially under alkaline conditions. To resolve this discrepancy, we propose a revolutionized pathway featuring the *O*OCHOH intermediate and the C–O bond dissociation of methanol. This mechanism, supported by control experiments and density functional theory (DFT) calculations, coexists with the conventional indirect pathway and explains the observed high C–O bond cleavage ratios (~65% in acid and &gt;75% in base). Moreover, mechanistic studies show that increasing hydroxide concentration enhances the oxidation state of Pt, modulating the reaction pathway and affecting the Faradaic efficiencies of CO2/CO32− and HCOOH /HCOO− products. These findings provide a fundamental understanding of methanol oxidation, emphasize the crucial role of surface oxygen coverage and pH, and strengthen methanol’s potential as a sustainable fuel and hydrogen carrier for energy storage and DMFC technologies.

Electrolyte effects play a fundamental role in electrocatalysis, influencing reaction kinetics, selectivity, and catalyst stability by altering interfacial interactions and charge distribution. This perspective reports recent advances to rationalise non-covalent interactions between electrolyte and surface adsorbates in electrocatalysis. Three main schools of thought have rationalised the effect of the electrolyte-adsorbates-surface interactions on the reaction kinetics, each based on different descriptors. The first suggests that non-covalent interactions with the electrolyte modify the binding energies of adsorbed intermediates. The second highlights the role of charge and electric fields near the electric double layer, shaped by the potential of zero charge, in stabilising polar adsorbates and governing proton transfer. The third focuses on energy barriers arising from the restructuring of the water solvation spheres of both electrolyte and reactants. We critically examine the main arguments and limitations of each framework, with a focus on hydrogen evolution and carbon dioxide reduction, and outline experimental challenges and future directions for elucidating electrolyte effects in electrocatalysis.

Understanding the role of Interfacial water structure/dynamics on the reaction barrier of (electro)chemical reactions represents an exciting opportunity to transform the designs of catalytic activity and selectivity. In this talk, we will examine the cation-dependent, pKa-dependent or pH-dependent reaction rates including water reduction and CO 2 reduction. The origin to these trends will be discussed in the context of local water-ion structures and solvation environments at the interface and the influence on electron transfer and proton-coupled electron transfer barriers. Such work provides molecular insights into potential use of chemical physics of electrolytes to control rates of reactions relevant to making of clean fuels and chemicals. Wang, Y. Zhang, B. Huang, B. Cai, R.R. Rao, L. Giordano, S.G. Sun and Y. Shao-Horn, Enhancing the Catalysis of Oxygen Reduction Reaction via Tuning Interfacial Hydrogen Bonds, Nature Catalysis, Nature Catalysis, 4 , 753, 2021. Huang, R.R. Rao, S. You, K. H. Myint, Y. Song, Y. Wang, W. Ding, L. Giordano, Y. Zhang, T. Wang, S. Muy, Y. Katayama, J. C. Grossman, A. P. Willard, K. Xu, Y. Jiang and Y. Shao-Horn, Cation- and pH-Dependent Hydrogen Evolution and Oxidation Reaction Kinetics, Journal of the American Chemical Society Au , [DOI: 10.1021/jacsau.1c00281], 2021. Reshma R. Rao, Botao Huang, Yu Katayama, Jonathan Hwang, Tomoya Kawaguchi, Jaclyn R. Lunger, Jiayu Peng, Yirui Zhang, Asuka Morinaga, Hua Zhou, Hoydoo You, Yang Shao-Horn, JPCC, 125 , 8195, Ye Tian, Botao Huang, Yizhi Song, Yirui Zhang, Dong Guan, Jiani Hong, Duanyun Cao, Enge Wang, Limei Xu, Yang Shao-Horn, Ying Jiang, Nature Communication, 15 , 7834, 2024. Sunmoon Yu, Hiroki Yamauchi, Shuo Wang, Abhishek Aggarwal, Junghwa Kim, Kiarash Gordiz, Botao Huang, Hongbin Xu, Daniel J Zheng, Xiao Wang, Haldrian Iriawan, Davide Menga, Yang Shao-Horn, Nature Catalysis , 7 , 1000, 2024.

Polymer electrolytes may play a crucial role in the development of safe, efficient, and energy-dense batteries thanks to their unique ability to facilitate ion transport while maintaining structural stability. However, experimental discovery is limited by the complexity of synthesizing and testing new monomer and polymer chemistries. In this study, we benchmark the ability of molecular dynamics (MD) simulations with Class 1 force fields to model the transport and structural properties of polymer electrolytes in a high-throughput screening setting. By systematically comparing simulation results to experimental data for 19 polymers, we evaluate the effect of simulation choices in predicting key transport properties. In particular, we evaluate the convergence of diffusivities and conductivities as a function of simulation length and how inaccuracies in modeling polymer glass-transition temperature carry over to ion transport properties. The results highlight both the strengths and limitations of affordable high-throughput MD simulations for these complex systems, providing insights into the optimization of MD simulations for polymer electrolyte research and recommendations for modeling choices with optimal cost-accuracy trade-offs. Furthermore, we perform in-depth transport and structural property analysis across the polymer space to gain insights into the design of new polymer electrolytes.

Electrolyte effects play a fundamental role in electrocatalysis, influencing reaction kinetics, selectivity, and catalyst stability by altering interfacial interactions and charge distribution. This perspective reports recent advances to rationalize non-covalent interactions between electrolyte and surface adsorbates in modulating the reaction kinetics in electrocatalysis. Three main schools of thought have rationalized the effect of the electrolyte-adsorbates-surface interactions on the reaction kinetics, each of them based on different descriptors: i) Non-covalent interactions with the electrolyte modify the binding energies of adsorbed reaction intermediates, which determine the energetic barriers and kinetics of a reaction. ii) The charge and electric field near the electric double layer, affected by the potential of zero charge of the catalyst surface, stabilize the energetics of the polar adsorbates and control the proton transfer kinetics. iii) Energy barriers arising from the restructuring of the water solvation spheres of both electrolyte and reactants affect the kinetics of the reaction. Herein, we will examine the main arguments and limitations of these three schools of thought, with a special focus on the hydrogen evolution and carbon dioxide electroreduction reactions to carbon monoxide and fuels and chemicals. Finally, we will analyze which ˈexperimental challengesˈ need to be overcome to accurately describe the electric double layer structure and electrolyte role in electrocatalysis.

Lithium (Li)-metal batteries (LMBs) are promising for high-energy applications but are hindered by dendrite formation and unstable interphases. This study investigated Li plating thermodynamics and kinetics as descriptors governing Coulombic efficiency (CE), focusing on lithium bis(fluorosulfonyl)imide in fluoroethylene carbonate and 1,2-dimethoxyethane electrolytes. First, upshifts in Li + /Li potential ( E Li + /Li vs Me 10 Fc), via low donor number solvents and high salt concentrations, correlated with increased CEs. Second, reaction (Δ S Li + Li ) and configurational entropy ( S C ), obtained via Seebeck coefficient and heat capacity measurements, respectively, did not correlate with CE and formed a minority contribution to Li + /Li reaction free energy, revealing the primarily enthalpic origin of the E Li + /Li correlation. Finally, kinetic analyses to examine the balance of exchange current density ( j 0 ) and diffusion ( D Li ) showing lower D Li / j 0 led to higher CE. These CE correlations highlight the combined effects of thermodynamics and kinetics on Li reversibility, informing rational strategies for enhanced performance of LMBs.