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1. Cooperative origin of proton pair diffusivity in yttrium substituted barium zirconate

   https://doi.org/10.1038/s42005-020-00464-5  

   Du, Peng; Chen, Qianli; Fan, Zhijun; Pan, Huizhu; Haibach, Frederick G.; Gomez, Maria A.; Braun, Artur (December 2020, Communications Physics)

   null (Ed.)

   Abstract Proton conduction is an important property for fuel cell electrolytes. The search for molecular details on proton transport is an ongoing quest. Here, we show that in hydrated yttrium doped barium zirconate using X-ray and neutron diffraction that protons tend to localize near the dopant yttrium as a conjugated superstructure. The proton jump time measured using quasi-elastic neutron scattering follows the Holstein-Samgin polaron model, revealing that proton hopping is weakly coupled to the high-frequency O-H stretching motion, but strongly coupled to low-frequency lattice phonons. The ratio of the proton polaron effective mass, m * , and the proton mass is m * / m  = 2, when coupled to the Zr-O stretching mode, giving experimental evidence of proton pairing in perovskites, as a result of proton-phonon coupling. Possible pathways of a proton pair are provided through Nudge Elastic Band calculations. The pairing of protons, when jumping, is discussed in context of a cooperative protonic charge transport process. 

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2. Ultra-thin proton conducting carrier layers for scalable integration of atomically thin 2D materials with proton exchange polymers for next-generation PEMs

   https://doi.org/10.1039/d3nr05202h  

   Moehring, Nicole K; Naclerio, Andrew E; Chaturvedi, Pavan; Knight, Thomas; Kidambi, Piran R (April 2024, Nanoscale)

   Scalable approaches for synthesis and integration of proton selective atomically thin 2D materials with proton conducting polymers can enable next-generation proton exchange membranes with minimal crossover while retaining adequate proton conductance. 

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3. Acid‐in‐Clay Electrolyte for Wide‐Temperature‐Range and Long‐Cycle Proton Batteries

   https://doi.org/10.1002/adma.202202063  

   Wang, Shitong; Jiang, Heng; Dong, Yanhao; Clarkson, David; Zhu, He; Settens, Charles_M; Ren, Yang; Nguyen, Thanh; Han, Fei; Fan, Weiwei; et al (May 2022, Advanced Materials)

   Abstract Proton conduction underlies many important electrochemical technologies. A family of new proton electrolytes is reported: acid‐in‐clay electrolyte (AiCE) prepared by integrating fast proton carriers in a natural phyllosilicate clay network, which can be made into thin‐film (tens of micrometers) fluid‐impervious membranes. The chosen example systems (sepiolite–phosphoric acid) rank top among the solid proton conductors in terms of proton conductivities (15 mS cm⁻¹at 25 °C, 0.023 mS cm⁻¹at −82 °C), electrochemical stability window (3.35 V), and reduced chemical reactivity. A proton battery is assembled using AiCE as the solid electrolyte membrane. Benefitting from the wider electrochemical stability window, reduced corrosivity, and excellent ionic selectivity of AiCE, the two main problems (gassing and cyclability) of proton batteries are successfully solved. This work draws attention to the element cross‐over problem in proton batteries and the generic “acid‐in‐clay” solid electrolyte approach with superfast proton transport, outstanding selectivity, and improved stability for room‐ to cryogenic‐temperature protonic applications. 

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4. Energy-Energy Correlator for Jet Production in $pp$ and $pA$ Collisions

   https://doi.org/10.1103/96xh-bd1w  

   Barata, João; Kang, Zhong-Bo; Mayo_López, Xoán; Penttala, Jani (June 2025, Physical Review Letters)

   In this Letter, we study the collinear limit of the energy-energy correlator in single-inclusive jet production in proton-proton and proton-nucleus collisions. We introduce a nonperturbative model that allows us to describe the energy-energy correlator in the entire angular region of the current experiments. Our results for proton-proton collisions show excellent agreement with CMS and ALICE data over a wide range of jet transverse momenta. For proton-nucleus collisions, we include modifications from the nuclear medium, and our predictions align well with the trends observed in recent ALICE measurements. 

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5. Proton Transfer from a Photoacid to a Water Wire: First Principles Simulations and Fast Fluorescence Spectroscopy

   https://doi.org/10.1021/acs.jpcb.1c07254  

   Walker, Alice R.; Wu, Boning; Meisner, Jan; Fayer, Michael D.; Martínez, Todd J. (November 2021, The Journal of Physical Chemistry B)

   NA (Ed.)

   Proton transfer reactions are ubiquitous in chemistry, especially in aqueous solutions. We investigate photoinduced proton transfer between the photoacid 8-hydroxypyrene-1,3,6- trisulfonate (HPTS) and water using fast fluorescence spectroscopy and ab initio molecular dynamics simulations. Photoexcitation causes rapid proton release from the HPTS hydroxyl. Previous experiments on HPTS/water described the progress from photoexcitation to proton diffusion using kinetic equations with two time constants. The shortest time constant has been interpreted as protonated and photoexcited HPTS evolving into an “associated” state, where the proton is “shared” between the HPTS hydroxyl and an originally hydrogen bonded water. The longer time constant has been interpreted as indicating evolution to a “solvent separated” state where the shared proton undergoes long distance diffusion. In this work, we refine the previous experimental results using very pure HPTS. We then use excited state ab initio molecular dynamics to elucidate the detailed molecular mechanism of aqueous excited state proton transfer in HPTS. We find that the initial excitation results in rapid rearrangement of water, forming a strong hydrogen bonded network (a “water wire”) around HPTS. HPTS then deprotonates in ≤3 ps, resulting in a proton that migrates back and forth along the wire before localizing on a single water molecule. We find a near linear relationship between the emission wavelength and proton-HPTS distance over the simulated time scale, suggesting that the emission wavelength can be used as a ruler for the proton distance. Our simulations reveal that the “associated” state corresponds to a water wire with a mobile proton and that the diffusion of the proton away from this water wire (to a generalized “solvent separated” state) corresponds to the longest experimental time constant. 

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