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1. In situ healing of dendrites in a potassium metal battery

   https://doi.org/10.1073/pnas.1915470117  

   Hundekar, Prateek; Basu, Swastik; Fan, Xiulin; Li, Lu; Yoshimura, Anthony; Gupta, Tushar; Sarbada, Varun; Lakhnot, Aniruddha; Jain, Rishabh; Narayanan, Shankar; et al (March 2020, Proceedings of the National Academy of Sciences)

   Significance Historically, battery self-heating has been viewed negatively as an undesirable attribute. However, we report that battery self-heat, if properly controlled, can smoothen dendritic features in potassium metal batteries. This could open the door to high gravimetric and volumetric energy density potassium-ion batteries that could offer a sustainable and low-cost alternative to the incumbent lithium-ion technology. 

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2. A compact dication source for Ba ²⁺ tagging and heavy metal ion sensor development

   https://doi.org/10.1088/1748-0221/18/07/P07044  

   Navarro, KE; Baeza-Rubio, J; Boyd, M; Foss, FW; Giri, S; Jones, BJP; Miller, RL; Nygren, DR; Samaniego, FJ; Stogsdill, K; et al (July 2023, Journal of Instrumentation)

   Abstract We present a tunable metal ion beam that delivers controllable ion currents in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed by sequential atomic evaporation and single or multiple electron impact ionization, followed by acceleration into a sensing region. Controllability of the ionic charge state is achieved through tuning of electrode potentials that influence the retention time in the ionization region. Barium, lead, and cadmium samples have been used to test the system, with ion currents identified and quantified using a quadrupole mass analyzer. Realization of a clean Ba²⁺  ion beam within a bench-top system represents an important technical advance toward the development and characterization of barium tagging systems for neutrinoless double beta decay searches in xenon gas. This system also provides a testbed for investigation of novel ion sensing methodologies for environmental assay applications, with dication beams of Pb²⁺and Cd²⁺also demonstrated for this purpose. 

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3. Metal Ion Sensing by BAPTA: Investigation Using 1H NMR Spectroscopy

   https://doi.org/10.47611/jsrhs.v11i4.3515  

   Adoni, Sunayna; Mologu, Trivikram; Igumenova, Tatyana (November 2022, Journal of Student Research)

   Many  biological  macromolecules  rely  on  metal  ions  to  maintain  structural  integrity  and  control  their  regulatory  function. In biological fluids, detection and identification of metal ions requires sensitive analytical tools with clear readouts.  In  this  work,  we  sought  to  investigate  the  potential  of  solution  Nuclear  Magnetic  Resonance  (NMR)  spectroscopy to analyze metal ion solutions and mixtures. To enable 1H NMR detection, we prepared the complexes of  eight  metal  ions  with  the  chelating  agent,  1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic  acid  (BAPTA).  The 1H NMR spectra were collected for BAPTA samples as a function of metal ion concentrations. The analysis of NMR data revealed that all metal ions with a notable exception of Mg2+ bind BAPTA with high affinities and form complexes with 1:1 metal-to-chelator stoichiometry. Both methylene and aromatic regions of the BAPTA 1H NMR spectra  experience  significant  changes  upon  the  metal  ion  complex  formation.  We  identified  the  spectroscopic  signatures  of  trivalent  and  paramagnetic  ions  and  demonstrated  that  the  binary  Zn2+/Pb2+  metal  ion  mixture  can  be  successfully analyzed by NMR. We conclude that complexation with BAPTA followed by the 1H NMR analysis is a sensitive method to detect and identify both nutritive and xenobiotic metal ions. 

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4. Nanopore Detection of Metal Ions: Current Status and Future Directions

   https://doi.org/10.1002/smtd.202000266  

   Roozbahani, Golbarg Mohammadi; Chen, Xiaohan; Zhang, Youwen; Wang, Liang; Guan, Xiyun (August 2020, Small Methods)

   Abstract In this review, recent research efforts that aimed at developing nanopore sensors for detection of metal ions, which play a crucial role in environmental safety and human health, are highlighted. Protein pores use three stochastic sensing‐based strategies for metal ion detection. The first strategy is to construct engineered nanopores with metal ion binding sites, so that the interaction between the target analytes and the nanopore can slow the movement of metal ions in the nanochannel. Second, large molecules such as nucleic acids and especially peptides can be utilized as external selective molecular probes to detect metal ions based on the conformational change of the ligand molecules induced by the metal ion–ligand chelation/coordination interaction. Third, enzymatic reactions can also be used as an alternative to the molecule probe strategy in the situation that a sensitive and selective probe molecule for the target analyte is difficult to obtain. On the other hand, by taking advantage of steady‐state analysis, synthetic nanopores mainly use two strategies (modification and modification‐free) to detect metals. Given the advantages of high sensitivity and selectivity, and label‐free detection, nanopore‐based metal ion sensors should find useful application in many fields, including environmental monitoring, medical diagnosis, and so on. 

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5. Differentiating Intra-Assembly and Interlayer Energy Transfer in Metal-Ion-Linked Molecular Multilayers

   https://doi.org/10.1021/acs.jpcc.4c04033  

   McLeod, Grace M; Nolder, Jackson; Arcidiacono, Ashley; Lindbom, Sarah; Dos_Santos, Nikolas R; Lambert, Ethan C; Ayad, Suliman; Beery, Drake; Alabugin, Igor V; Hanson, Kenneth (October 2024, The Journal of Physical Chemistry C)

   Metal-ion-linked molecular multilayers on metal oxide surfaces are promising for applications ranging from solar energy conversion to sensing. Most of these applications rely on energy and electron transfer between layers/molecules which can be envisioned to occur via intra-assembly (IA; between metal-ion-linked molecules) and interlayer (IL; between separate layers of nonlinked molecules) processes. Here, we describe our effort to differentiate between IL and IA energy transfer using a bilayer composed of ZrO2, a phosphonated anthracene derivative (A), a zinc(II) linking ion, and a Pt(II)porphyrin (P). Both time-resolved emission and transient absorption measurements show no impact of diluting the anthracene layer with a spectroscopically inert spacer on the rate of 1A* to P and 3P* to A, singlet, and triplet energy transfer, respectively. These results indicate that energy transfer within the metal-ion-linked assembly (i.e., ZrO2-A–Zn-P) is more rapid than with an adjacent, nonlinked A molecule, even for a P derivative capable of laying down on the surface. These insights are an important step toward structural design principles maximizing the efficiency/rate of energy transfer in multilayer assemblies. 

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