Erli Lu

We report highly efficient mechanochemical redox reactivity between polytetrafluoroethylene (PTFE) and base metals, enabling simultaneous polymer decomposition, fluorination of metals without F ₂ or HF, and mechanochemical dealloying. While milling with metals has recently emerged as a mechanochemical platform for PTFE defluorination, most such work has relied on highly reactive, air‐sensitive metals, such as alkali elements. We now demonstrate a proof‐of‐principle for direct and efficient transformation of PTFE into a mixture of sp ² ‐carbon and a metal fluoride by ball‐milling with stoichiometric amounts of safe‐to‐handle, abundant, inexpensive metals such as zinc. The reactivity is applicable to other metals, as shown by aluminum, lead and cadmium, and the process is also extendable into a two‐step, one‐pot mechanochemical strategy to generate NaF as a recycled fluorine source, along with a ZnO/carbon mixture which can undergo carbothermal reduction to recover zinc, suggesting an opportunity to develop a zinc‐based PTFE defluorination cycle. Moreover, ball‐milling with PTFE is shown to transform brass into a mixture of copper metal and ZnF ₂ , providing a proof‐of‐principle for mechanochemical dealloying of mixed‐metal materials using fluoropolymer waste as a reagent. This work introduces a different, mechanochemistry‐based paradigm for straightforward, atom‐economic, and potentially more sustainable PTFE defluorination, presenting its valorization as a mechanochemical fluorinating agent.

We report highly efficient mechanochemical redox reactivity between polytetrafluoroethylene (PTFE) and base metals, enabling simultaneous polymer decomposition, fluorination of metals without F ₂ or HF, and mechanochemical dealloying. While milling with metals has recently emerged as a mechanochemical platform for PTFE defluorination, most such work has relied on highly reactive, air‐sensitive metals, such as alkali elements. We now demonstrate a proof‐of‐principle for direct and efficient transformation of PTFE into a mixture of sp ² ‐carbon and a metal fluoride by ball‐milling with stoichiometric amounts of safe‐to‐handle, abundant, inexpensive metals such as zinc. The reactivity is applicable to other metals, as shown by aluminum, lead and cadmium, and the process is also extendable into a two‐step, one‐pot mechanochemical strategy to generate NaF as a recycled fluorine source, along with a ZnO/carbon mixture which can undergo carbothermal reduction to recover zinc, suggesting an opportunity to develop a zinc‐based PTFE defluorination cycle. Moreover, ball‐milling with PTFE is shown to transform brass into a mixture of copper metal and ZnF ₂ , providing a proof‐of‐principle for mechanochemical dealloying of mixed‐metal materials using fluoropolymer waste as a reagent. This work introduces a different, mechanochemistry‐based paradigm for straightforward, atom‐economic, and potentially more sustainable PTFE defluorination, presenting its valorization as a mechanochemical fluorinating agent.

Mechanochemical reactions can access unusual and useful reactivity, but the electron-transfer steps that govern many of these mechanochemical transformations have remained difficult for time-resolved monitoring. Here we establish a time-resolved strategy for resolving mechanochemical electron transfer by integrating in-situ powder X-ray diffraction with ex-situ quantitative electron paramagnetic resonance, solid-state nuclear magnetic resonance, and magnetometry. Using the formation of a sodium anion complex (sodide) as a model reaction, we show that a mechanically driven disproportionation proceeds through a stepwise pathway involving an electride intermediate. This finding provides direct mechanistic insight into how electrons move through reactive solids under mechanochemical condition. More broadly, it establishes a general experimental blueprint for identifying electronically distinct transient intermediates in mechanochemical redox chemistry.

Fluoropolymers and other per- and polyfluoroalkyl substances (PFAS) are among the most persistent anthropogenic materials. Although bulk fluoropolymers such as polytetrafluoroethylene (PTFE) are often regarded as chemically inert, weathering and abrasion generate long-lived fluorinated microplastics, while molecular PFAS accumulate in the environment as mobile contaminants. Existing destruction strategies can cleave C–F bonds, but typically require incineration or aggressive reagents and frequently generate water-soluble fluoride products that remain environmentally problematic. Here we show that calcium metal enables solvent-free mechanochemical defluorination of PTFE and perfluorooctanoic acid (PFOA) at ambient starting temperature without external heating, while irreversibly sequestering fluorine as calcium fluoride, a nontoxic, insoluble, and environmentally benign solid. Quantitative solid-state 19F NMR, with detection limits explicitly assessed, shows no resolvable PTFE after 30 min of milling with Ca and Mg (<1.0% residual PTFE); Sr gives near-complete conversion (<10% residual PTFE), whereas Ba gives only partial (∼64% residual PTFE) conversion after 30 min of milling. TEM and SEM-EDX reveal CaF2-rich nanocrystalline domains intimately mixed with an oxygen-containing disordered carbonaceous material. By coupling efficient defluorination with fluoride sequestration, this work establishes a mechanochemical strategy for mineralization of persistent fluorinated materials without generating soluble alkali-metal fluoride waste as a secondary environmental hazard, while defining the analytical and process-safety constraints relevant to further development.

We use reactive molecular dynamics to predict electrolyte reaction pathways relevant to solid electrolyte interphase formation in anode-free batteries.

This perspective provides an overview of recent methods (since 2023) enabling the degradation of PTFE at low temperature (≤100 °C) forming useful fluoride salts, which in some cases can be upcycled into valuable fluorinated fine chemicals.

Grain boundaries (GBs) are ubiquitous in polycrystalline solid electrolytes and play pertinent roles in determining their ionic conductivity, electronic properties and stability. Despite their importance, the impact of GBs on lattice dynamics in solid electrolytes has not been elucidated. In this work, first‐principles phonon calculations are undertaken on the GBs of a model solid electrolyte, namely, anti‐perovskite Li ₃ OCl, to explore their influence on lattice dynamics and the potential consequences for Li‐ion transport. Our results indicate that Li‐ion vibrational hardening exists within the GBs, which suggests an increased barrier for Li‐ion transport, in agreement with both previous experimental and computational studies. Conversely, the anion sublattice in the GBs undergoes vibrational softening, which has been related to an increase in motion and potential for detrimental side reactions, leading to structural degradation and potentially device failure. Furthermore, consideration of the alignment between the Li‐ion migration pathways and eigenvectors of Li‐ion vibrations indicates a poorer alignment on average in the GBs compared to the bulk. This study provides a proof of concept for the simulation of lattice dynamics at solid electrolyte GBs and links the connections made between bulk materials and phonon properties with the phenomenon of GB resistance for the first time.

α‐Silyl alkyl complexes, such as the ubiquitous MCH ₂ SiMe ₃ , are some of the most used organometallic building blocks and reagents. Hitherto, most reports focus on the reactive metal–carbon bond, while the carbon–silicon bond has thus far been limited to a handful of serendipitous reaction patterns. Herein, by examining a range of reactions between mononuclear Li or Na α‐silyl alkyl complexes and CO, CO ₂ , or heteroallenes (isocyanates, isothiocyanates, carbodiimides), we report tandem M─C and C─Si bond reactivity, with in‐depth mechanistic understanding unveiled by computational reaction pathway studies enabled by the artificial force induced reaction (AFIR) method. By bringing the long‐neglected C─Si bond reactivity to the awareness of synthetic chemists, we demonstrate that the C─Si bond should be taken into account in reaction design when using these α‐silyl alkyl complexes.

α‐Silyl alkyl complexes, such as the ubiquitous MCH ₂ SiMe ₃ , are some of the most used organometallic building blocks and reagents. Hitherto, most reports focus on the reactive metal–carbon bond, while the carbon–silicon bond has thus far been limited to a handful of serendipitous reaction patterns. Herein, by examining a range of reactions between mononuclear Li or Na α‐silyl alkyl complexes and CO, CO ₂ , or heteroallenes (isocyanates, isothiocyanates, carbodiimides), we report tandem M─C and C─Si bond reactivity, with in‐depth mechanistic understanding unveiled by computational reaction pathway studies enabled by the artificial force induced reaction (AFIR) method. By bringing the long‐neglected C─Si bond reactivity to the awareness of synthetic chemists, we demonstrate that the C─Si bond should be taken into account in reaction design when using these α‐silyl alkyl complexes.

Ligand- and metal identity-effects in organo-alkali metal reagents induced ortho-selective C(sp ² )–H activation.