Recent ucb_chemistry items

Catalytic Borylation of Poly(vinyl chloride) Produces Adhesive Materials

Mon, 31 Aug 2026 00:00:00 +0000

Postpolymerization functionalization of polymers can create new applications for existing materials, while retaining their most favorable, intrinsic properties. Polyvinyl chloride (PVC) is a widely used, commodity polymer that is particularly challenging to modify. We report a copper-catalyzed protocol that replaces a small fraction of the C-Cl bonds in PVC with C-B bonds to boronic esters. The reaction occurs with an inexpensive catalyst comprising copper(II) chloride and an NHC ligand derived from a common ionic liquid that is distinct from the N-heterocyclic carbene (NHC) used for the borylation of small alkyl halides. The resulting materials adhere strongly to common surfaces, such as glass and metals, even more strongly than do commercial glues.

Multimodal Nanoscale Mapping of Local Structure and CO2 Adsorption in Metal–Organic Frameworks

Mon, 31 Aug 2026 00:00:00 +0000

Diamine functionalization of the metal-organic framework Mg₂(dobpdc) (dobpdc^4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) significantly enhances its selectivity for CO₂ capture from flue gases and air. The structure and CO₂ capacity of such materials are typically assessed using bulk techniques that rely on averaging signal over large ensembles of unit cells, obscuring local heterogeneities, such as variations in CO₂ occupancy across individual nanocrystals. To resolve this limitation, we demonstrate a multimodal, nanoscale characterization of Mg₂(dobpdc) appended with 1,3-diaminopropane. By employing recently developed characterization techniques at progressively smaller length scales, we uncover insights from correspondingly smaller populations of unit cells. First, we use parallel-beam 3D electron diffraction (3D ED) to identify a prominent expansion in lattice parameters upon desorption of CO₂, as...

Hydrogen Electrocatalysis on Perfluorosulfonic-Acid-Coated Pt

Thu, 27 Aug 2026 00:00:00 +0000

Membrane-electrode assemblies utilize ionomer-coated electrocatalysts to achieve facile ion transport. Consequently, isolation of intrinsic catalyst kinetics from measured polarization curves is challenging, as the properties of the catalyst and ionomer both affect the measurements. Here, we employ a Pt microelectrode coated by a thin perfluorosulfonic acid (PFSA) layer to measure polarization curves for the hydrogen oxidation reaction/hydrogen evolution reaction (HER/HOR). Intrinsic electrode kinetics are isolated by theoretical analysis of the local catalyst microenvironment, accounting for mass transport and thermodynamics. The observed enhancements in HER and HOR rates with increasing relative humidity (RH) at the working electrode are attributable to two competing factors: the decrease in activity of H+ in the ionomer and the dominant decrease in the water reorganization energy in the Marcus–Hush–Chidsey representation of HER/HOR kinetics. The increase in intrinsic rate with...

Generalizable Porous Aromatic Framework‐Included Polymer Membranes for Diffusion‐Enhanced Gas Separations

Thu, 27 Aug 2026 00:00:00 +0000

Industrial separation processes account for 10-15% of global energy consumption. Membrane-based processes are less energy-intensive than traditional gas separation technologies; however, enhanced material separation performance and stability for numerous gas mixtures are needed for widespread industrial adoption. This work presents a generalizable strategy for preparing mixed-matrix gas separation membranes exceeding the performance upper bounds of existing polymer membranes for a wide variety of industrial gases. By incorporating robust porous aromatic framework (PAF) particles into various dense commercial polymer matrices, gas diffusivity and solubility can be enhanced. For diverse gas mixtures (e.g., CO₂/N₂, O₂/N₂, He/CH₄, H₂/N₂, and C₂H₄/C₂H₆), the resulting composite membranes exhibit enhanced gas permeabilities-by as much as 520%-and largely unchanged...

Machine-Learned Leftmost Hessian Eigenvectors for Robust Transition State Finding

Wed, 26 Aug 2026 00:00:00 +0000

The reliable determination of transition states (TSs) benefits from second-order information for robust convergence and validation, but the computational expense of Hessians prohibits their routine use in TS optimization. Here, we present a machine-learning-driven TS optimizer that directly predicts the leftmost Hessian eigenvector (LMHE), which is the critical mode that locally approximates the reaction coordinate encompassing the TS. We demonstrate that our LMHE optimizer recovers TS solutions at the same rate as full-Hessian optimizers and robustly from degraded initial guess geometries, thereby eliminating the excessively long wall times characteristic of full-Hessian approaches and reducing total gradient evaluations compared to standard quasi-Newton methods. We further improve accuracy and robustness using uncertainty quantification for identifying occasional LMHE prediction failures, where we then fall back to a full-Hessian update from the machine-learned potential at...

Local pH control for impure-water-fed bipolar-membrane electrolyzers

Mon, 24 Aug 2026 00:00:00 +0000

We show that the pH gradient at the catalyst–ion exchange membrane interface in a seawater bipolar-membrane electrolyzer can be mitigated by reducing the catalyst–membrane distance. We further show how water transport can be balanced at steady state. Bipolar membrane (BPM) electrolyzers offer advantages in the electrolysis of impure-waters by controlling ion flux, yet still suffer from performance and durabilty limitations. Here, we investigate the impact of NaCl electrolyte (nominally simulated seawater) on BPM electrolyzer operation and identify local pH gradients at electrode–membrane interfaces, arising from coupled ion transport and electrode reactions, as one origin of performance loss and degradation. NaCl in the catholyte induces pronounced pH gradients at the cathode|cation-exchange-layer interface, leading to increased voltage, while partial Cl − crossover to the anode becomes detrimental under locally OH − -deficient conditions, promoting the chlorine evolution reaction...

Oxidative Cascade Cyclization of 1,2-Dicyanoarenes by a Dicopper(I,I) Nitrite Complex to Phthalimide Ligands

Fri, 21 Aug 2026 00:00:00 +0000

The reactions of [Cu2(μ–κ 1:κ 1 -O2N)DPFN][NTf2] (1; DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine, NTf2 – = N(SO2CF3)2 –) with 1,4-dicyanobenzene and 1,2-dicyanoarenes are discussed. Treatment of 1 with 1,4-dicyanobenzene produces a tetra-Cu(I) terephthalate complex (2) and dinitrogen via a discrete CN triple bond cleavage at each cyano group. However, reactions of 1 with 1,2-dicyanoarenes appear to proceed via a cascade reaction involving two intertwined CN triple bond activations to yield a series of di-Cu(I) phthalimides, [Cu2(μ–N(CO)2(Ar))DPFN][NTf2] (3-(Ar); Ar = 1,2-arylenes C6H4, 3-NO2C6H3, 4-NO2C6H3, 4-PrOC6H3, 3-NC5H3) and dinitrogen. The dicopper phthalimide bonding interaction in these compounds is robust enough to resist protonation by pentafluorophenol and alkylation by methyl triflate or benzyl chloride at the imide nitrogen. This characteristic presents an opportunity for postsynthetic modifications of the phthalimide ligand. Nevertheless,...

Operation-Induced BiVO4 Surface Reconstruction Modulates Photoelectrochemical Glycerol Photooxidation Stability and Activity

Thu, 20 Aug 2026 00:00:00 +0000

Abstract Operation-induced surface reconstruction of photoelectrodes is underexplored as a path to control stability and performance. We show how adaptive junctions form via surface reconstruction of BiVO4 during glycerol photooxidation and how these surfaces affect electrolyte-dependent kinetics and durability. Preferential V dissolution in both acidic and alkaline media forms a Bi-rich layer. In situ measurements through a dual-working-electrode platform quantify the changes in photovoltage and charge-transfer resistance derived from adaptive junction formation, while enabling quantitative separation of the driving forces for charge separation and interfacial catalysis. The reconstructed surface in acidic media improves hole-transfer kinetics, functions as a glycerol-oxidation catalyst, and imparts photostability. Surface reconstruction in alkaline media exhibits the opposite behavior, impeding hole injection. This instability is mitigated by trace Ni2+ ions, which drive in...

Plutonium(III) versus uranium(III) and samarium(III) in small molecule activation chemistry

Thu, 20 Aug 2026 00:00:00 +0000

We report the PuIII complex, [PuIII(CpMe4)3] (1-Pu), and demonstrate its differences in small molecule reactivity compared to the UIII and SmIII analogs, [UIII(CpMe4)3] (1-U) and [SmIII(CpMe4)3] (1-Sm), respectively. 1-Pu reductively cleaves the small molecule (PhS)2, affording a PuIII complex, [{PuIII(CpMe4)2}2(μ-SPh)2] (2-Pu), while retaining the PuIII center and eliminating (CpMe4)2 as a by-product, a fingerprint of a sterically induced reduction (SIR) reaction. Sm is often used as a surrogate for Pu, but the analogous [SmIII(CpMe4)3], (1-Sm), is unreactive. The (PhS)2 cleavage by 1-U proceeds solely via a metal-based oxidation (i.e., UIII → UIV), to form [UIV(CpMe4)3(SPh)] (3-U). Only 1-U reacts with (PhHN)2, affording the reductive cleavage product, [UIV(CpMe4)3(NHPh)] (4-U). The difference in reactivity of 1-Pu compared to complexes 1-Sm and 1-U was unexpected, and since SIR chemistry can enable complexes to participate in otherwise impossible reductive transformation of...

Polyketide synthase-based controlled synthesis of polycyclopropanated fuel molecules

Thu, 20 Aug 2026 00:00:00 +0000

Reducing carbon emissions from aviation and long-distance transportation sectors requires the development of sustainable biofuels with suitable energy density, freezing point, and other physical properties. We previously demonstrated biological production of high energy polycyclopropanated fatty acids (POP-FAs, class I) using an iterative polyketide synthase (iPKS) pathway in a Streptomyces host. Here, we used a computational model of fuel properties to identify chain length and cyclopropanation control as critical steps to engineer this iPKS for biofuel applications. We next explored the natural diversity of POP biosynthesis by investigating homologous pathways. Then, by in vivo gene exchange, we determined cyclopropanase (CP) catalysis to be key for POP-FA engineering. Leveraging both natural and engineered pathway product diversity, we demonstrate targeted production of improved POP-FAs, namely shortened POP-FAs with predicted superior freezing point properties for aviation,...

Catalytic Ambient Temperature Dinitrogen Conversion to a Bis(silyl)amine by Mononuclear Group 4 Aryloxide Complexes

Tue, 18 Aug 2026 00:00:00 +0000

The homogeneous conversion of ambient dinitrogen to amine products via the N₂ reduction reaction (N₂RR) remains a prized yet challenging feat for d-block complexes and is scarcely reported for f-block complexes. New, mononuclear Ti^IV and Zr^IV aryloxide complexes Ti(DP)₂ (1Ti), Zr(DP)₂ (1Zr), and DP = [2-(OC₆H₂-2-^tBu,4-Me)₂CHPh] produce up to 51 eq. and up to 7.0 eq. of HN(SiMe₃)₂ per Ti/Zr, from N₂, K⁰, weak acid, and chlorotrimethylsilane. Complex 1Ti exhibits more than double the activity toward N₂-silylation of any previously reported Ti N₂RR catalyst and can also catalyze the formation of up to 19 eq. of NH₃, a new feature in early metal N₂RR chemistry. The mononuclear 1Zr is the most active Zr catalyst for N₂-silylation to date. [KSm(DP)₂(THF)₃]...

Surface Hydroxyls of Imogolite Nanotubes Drive Distinct Structures and Mobility Differentiation of Nanoconfined Water

Mon, 17 Aug 2026 00:00:00 +0000

Abstract Nanoconfined fluids, particularly water, govern subsurface geochemistry, yet the molecular-level mechanisms by which mineral surfaces dictate confined water structure and mobility remain poorly resolved. Here, we combine solution- and solid-state proton (1H) NMR spectroscopy, NMR relaxometry, modulated-gradient spin–echo (MGSE) NMR diffusometry, infrared spectroscopy, and molecular dynamics simulations to demonstrate that surface hydroxyls drive the structural and dynamic differentiation of water in imogolite nanotubes. In saturated suspensions, we observe the coexistence of distinct water 1H environments, each exhibiting significantly reduced mobility, which we attribute to strong interactions with the imogolite surfaces. As more mobile water is removed, long-range water diffusivity in the fibrous solid samples slows to 1.6 × 10–10 m2·s–1 while local fluctuations increase to 3.4 × 10–8 m2·s–1, indicating a significant increase in molecular restriction through surface...

Low-voltage syngas synthesis via BPM electrolysis of CO 2 capture and aldehyde solution

Mon, 3 Aug 2026 00:00:00 +0000

A bipolar membrane electrolyzer coupling bicarbonate electrolysis with formaldehyde oxidation directly produces syngas (H 2 : CO = 1) at 1.7 V and 200 mA cm −2 with 200% combined Faradaic efficiency. We demonstrate an electrochemical syngas production platform that couples bicarbonate electrolysis with formaldehyde oxidation in a bipolar membrane electrode assembly. This strategy doubles syngas (CO + H 2 ) throughput compared to conventional CO 2 electrolysis by generating CO at the cathode and H 2 at the anode. The system achieves a full-cell voltage of 1.7 V while operating at an industrially relevant current density of 200 mA cm −2 . The system maintained a combined Faradaic efficiency of 200% over 8 hours. The process produces syngas with a 1 : 1 H 2 : CO ratio, aligning with downstream requirements for Fischer–Tropsch synthesis. We further investigated how Cu anode active sites and electrolyte composition affect formaldehyde oxidation activity. Our integrated electrolytic...

Structure of iridium oxide catalysts dictates performance differences for proton exchange membrane water electrolyzers

Fri, 31 Jul 2026 00:00:00 +0000

A systematic catalyst loading study reveals the higher catalytic activity of amorphous iridium oxide arises from bulk participation via suggested electrochemical descriptors, while identifying loading-independent intrinsic electrochemical properties. Proton exchange membrane water electrolyzers (PEMWEs) are promising zero-emission technologies. However, their high cost remains a barrier to widespread adoption. Iridium oxide is commonly used as an oxygen evolution reaction (OER) catalyst, and its cost and scarcity make it essential to reduce its loading while increasing its activity. Evaluation of iridium oxide activity should be carried out in the membrane electrode assembly (MEA) configuration to replicate realistic operating conditions. Herein, we present a comprehensive benchmarking framework to accurately evaluate the amorphous and crystalline iridium oxides at the MEA level. By systematically varying the catalyst loading, this study confirmed that each MEA was utilized...

Activating magnetite ores for aqueous ironmaking at high current densities

Fri, 31 Jul 2026 00:00:00 +0000

Low-temperature electrochemical cells reducing iron oxides to metal in alkaline electrolytes can support fully electrified steelmaking processes. Previous studies on these cells have primarily focused on high-surface-area hematite, Fe 2 O 3 , reactants... Low-temperature electrochemical cells reducing iron oxides to metal in alkaline electrolytes can support fully electrified steelmaking processes. Previous studies on these cells have primarily focused on high-surface-area hematite, Fe 2 O 3 , reactants whereas attempts to reduce suspensions of magnetite, Fe 3 O 4 —one of the two feedstocks for existing ironmaking reactors—have generally been limited to low rates of reaction (<30 mA cm -2 ). Here, we control the crystalline domain size of Fe 2 O 3 and Fe 3 O 4 particles in 10 M NaOH electrolytes to study how the nanoscale morphology of oxides controls the rate of electrochemical ironmaking. Rotating-ring disk electrode measurements of Fe 2+ , in-situ Raman spectroscopy of...

Correction to “Anions in Corrosion: Influence of Polymer Electrolytes on the Interfacial Ion Transfer Kinetics of Cu at Au(111) Surfaces”

Fri, 31 Jul 2026 00:00:00 +0000

Correction to “Anions in Corrosion: Influence of Polymer Electrolytes on the Interfacial Ion Transfer Kinetics of Cu at Au(111) Surfaces”

Anion-exchange membrane water electrolysis: insights from round-robin testing

Fri, 31 Jul 2026 00:00:00 +0000

As research and industrial interest in anion-exchange membrane water electrolysis (AEMWE) grows, there is an increasing need for reliable baselines and cross-lab validation of results. The wide variety of material sets and operating conditions under consideration for AEMWE has thus far limited efforts for standardization. In this study, round-robin testing was conducted in deionized water and KOH-based supporting electrolyte by 5 institutions from academia, national laboratories, and industry to provide baseline performance data and identify sources of cross-lab variability. Baseline membrane electrode assemblies were fabricated with commercial catalysts, membranes, and transport layers using standard techniques and tested using reagent-grade electrolytes, aiming for accessibility rather than state-of-the-art performance. From all tests, the average voltage at 1 A/cm2 was 2.72 ± 0.17 V and 1.87 ± 0.03 V in deionized water and 0.1 M KOH, respectively. The maximum in-house and cross-lab...

Anions in Corrosion: Influence of Polymer Electrolytes on the Interfacial Ion Transfer Kinetics of Cu at Au(111) Surfaces

Fri, 31 Jul 2026 00:00:00 +0000

The corrosion kinetics of metals in the presence of polymer electrolyteswhich are frequently used in devices for the electrochemical production of hydrogen, hydrocarbons, and alcoholsis convoluted by transport and ill-defined reactive interfaces that mask the fundamental reaction kinetics. Underpotential-deposited monolayers of Cu at Au(111) surfaces provide a structurally well-defined active site for interfacial ion transfer with a fixed number of sites available for adsorption. Here, we investigate the adsorption behavior of Cu at Au(111) surfaces across a series of sulfate and sulfonate electrolytes to understand how anion structure influences the kinetics of elementary interfacial ion-transfer reactions. The influence of anion structure is most significant at high adsorbate coverage, with similar adsorption isotherms and kinetics observed for sulfates and two molecular sulfonates. In contrast, a suspended perfluorosulfonic acid ionomer reduced both the equilibrium coverage...

Ion Dynamics and Polarizations in a Simulated Nanopore under Alternating Current Controls

Fri, 31 Jul 2026 00:00:00 +0000

Understanding ion transport through nanopores provides a central basis in advancing the design of molecular sensors or the preparation of biomimetic systems. Here we report a continuum modeling approach that introduces an alternating current field to investigate the competition between a surface-charge dominated electromigration process under a frequency induced ion dynamics at nanoscales. We highlight a transition from a surface-charge-dominated effect, where electric double layer impacts prevail, to bulk-like ion dynamics as pore dimensions approach the microscale. Results reveal that rapid electromigration dominates ion distribution at a millisecond time scale, generating transient, non-equilibrium concentration profiles. In contrast, lower frequency perturbations enable diffusion to equilibrate ion distributions within each cycle, establishing periodic quasi-steady states. The findings from this work highlight the interplay of ion selectivity and distribution by exploiting...

In-Situ tuning of Catalyst Surface Chemistry for Understanding Proton-Transfer in Bipolar Membranes