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Ni2MnSi crystallizes in the tetragonal P4/mmm space group. The structure is two-dimensional and consists of one manganese molecule and one Ni2Si sheet oriented in the (0, 0, 1) direction. In the Ni2Si sheet, Ni1+ is bonded in a 4-coordinate geometry to four equivalent Si4- atoms. All Ni–Si bond lengths are 2.37 Å. Si4- is bonded in a body-centered cubic geometry to eight equivalent Ni1+ atoms.
MnSiP2 is Chalcopyrite structured and crystallizes in the tetragonal I-42d space group. The structure is three-dimensional and consists of four manganese molecules and one SiP2 framework. In the SiP2 framework, Si4- is bonded to four equivalent P1+ atoms to form corner-sharing SiP4 tetrahedra. All Si–P bond lengths are 2.27 Å. P1+ is bonded in a bent 120 degrees geometry to two equivalent Si4- atoms.
MnO3SO3 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four manganese;trihydrate molecules and four sulfur trioxide molecules.
Mn(SmSb)2Sb crystallizes in the tetragonal P4/mmm space group. The structure is zero-dimensional and consists of one antimony molecule, one manganese molecule, and two stibanylidynesamarium molecules.
Mn(Tb5(Mn2C3)3)2 crystallizes in the cubic I-43m space group. The structure is three-dimensional and consists of two manganese molecules and one Tb5(Mn2C3)3 framework. In the Tb5(Mn2C3)3 framework, there are two inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded to eight C+3.11- atoms to form distorted TbC8 hexagonal bipyramids that share edges with two equivalent TbC8 hexagonal bipyramids, edges with four equivalent TbC6 pentagonal pyramids, and faces with four equivalent TbC8 hexagonal bipyramids. There are four shorter (2.49 Å) and four longer (2.62 Å) Tb–C bond lengths. In the second Tb3+ site, Tb3+ is bonded to six equivalent C+3.11- atoms to form distorted TbC6 pentagonal pyramids that share corners with six equivalent TbC6 pentagonal pyramids and edges with six equivalent TbC8 hexagonal bipyramids. There are three shorter (2.57 Å) and three longer (2.66 Å) Tb–C bond lengths. Mn2+ is bonded in a distorted trigonal non-coplanar geometry to three C+3.11- atoms. There is two shorter (1.86 Å) and one longer (2.08 Å) Mn–C bond length. There are two inequivalent C+3.11- sites. In the first C+3.11- site, C+3.11- is bonded to four Tb3+ and two equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing CTb4Mn2 octahedra. The corner-sharing octahedra tilt angles range from 3–69°. In the second C+3.11- site, C+3.11- is bonded in a 7-coordinate geometry to four equivalent Tb3+, two equivalent Mn2+, and one C+3.11- atom. The C–C bond length is 1.38 Å.
(MgGe)2Mn crystallizes in the tetragonal P4/mmm space group. The structure is zero-dimensional and consists of one manganese molecule and two MgGe clusters. In each MgGe cluster, Mg is bonded in a single-bond geometry to one Ge atom. The Mg–Ge bond length is 2.58 Å. Ge is bonded in a single-bond geometry to one Mg atom.
Mn(PrSb)2Sb crystallizes in the tetragonal P4/mmm space group. The structure is zero-dimensional and consists of one antimony molecule, one manganese molecule, and two PrSb clusters. In each PrSb cluster, Pr3+ is bonded in a single-bond geometry to one Sb+2.67- atom. The Pr–Sb bond length is 2.73 Å. Sb+2.67- is bonded in a single-bond geometry to one Pr3+ atom.
Mn(Y5(Mn2C3)3)2 crystallizes in the cubic I-43m space group. The structure is three-dimensional and consists of two manganese molecules and one Y5(Mn2C3)3 framework. In the Y5(Mn2C3)3 framework, there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to eight C+3.11- atoms to form distorted YC8 hexagonal bipyramids that share edges with two equivalent YC8 hexagonal bipyramids, edges with four equivalent YC6 pentagonal pyramids, and faces with four equivalent YC8 hexagonal bipyramids. There are four shorter (2.49 Å) and four longer (2.62 Å) Y–C bond lengths. In the second Y3+ site, Y3+ is bonded to six equivalent C+3.11- atoms to form distorted YC6 pentagonal pyramids that share corners with six equivalent YC6 pentagonal pyramids and edges with six equivalent YC8 hexagonal bipyramids. There are three shorter (2.56 Å) and three longer (2.65 Å) Y–C bond lengths. Mn2+ is bonded in a distorted trigonal non-coplanar geometry to three C+3.11- atoms. There is two shorter (1.86 Å) and one longer (2.08 Å) Mn–C bond length. There are two inequivalent C+3.11- sites. In the first C+3.11- site, C+3.11- is bonded to four Y3+ and two equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing CY4Mn2 octahedra. The corner-sharing octahedra tilt angles range from 3–70°. In the second C+3.11- site, C+3.11- is bonded in a 7-coordinate geometry to four equivalent Y3+, two equivalent Mn2+, and one C+3.11- atom. The C–C bond length is 1.38 Å.
(Er5(Mn2C3)3)2Mn crystallizes in the cubic I-43m space group. The structure is three-dimensional and consists of two manganese molecules and one Er5(Mn2C3)3 framework. In the Er5(Mn2C3)3 framework, there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to eight C+3.11- atoms to form distorted ErC8 hexagonal bipyramids that share edges with two equivalent ErC8 hexagonal bipyramids, edges with four equivalent ErC6 pentagonal pyramids, and faces with four equivalent ErC8 hexagonal bipyramids. There are four shorter (2.45 Å) and four longer (2.60 Å) Er–C bond lengths. In the second Er3+ site, Er3+ is bonded to six equivalent C+3.11- atoms to form distorted ErC6 pentagonal pyramids that share corners with six equivalent ErC6 pentagonal pyramids and edges with six equivalent ErC8 hexagonal bipyramids. There are three shorter (2.56 Å) and three longer (2.64 Å) Er–C bond lengths. Mn2+ is bonded in a distorted trigonal non-coplanar geometry to three C+3.11- atoms. There is two shorter (1.87 Å) and one longer (2.06 Å) Mn–C bond length. There are two inequivalent C+3.11- sites. In the first C+3.11- site, C+3.11- is bonded to four Er3+ and two equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing CEr4Mn2 octahedra. The corner-sharing octahedra tilt angles range from 4–69°. In the second C+3.11- site, C+3.11- is bonded in a 7-coordinate geometry to four equivalent Er3+, two equivalent Mn2+, and one C+3.11- atom. The C–C bond length is 1.39 Å.
MnOs2Si is Cyanogen Chloride-like structured and crystallizes in the orthorhombic Immm space group. The structure is zero-dimensional and consists of two manganese molecules and two Os2Si clusters. In each Os2Si cluster, Os1+ is bonded in a single-bond geometry to one Si4- atom. The Os–Si bond length is 2.19 Å. Si4- is bonded in a linear geometry to two equivalent Os1+ atoms.
Mn(SnF2)3 is Cyanogen Chloride-like structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one manganese molecule and three tin(ii) fluoride molecules.
Mn(H2O)6(C3N2H6)4(H2O)4Cl2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two hydrochloric acid molecules, one manganese hexahydrate molecule, two methenamine molecules, and four water molecules.
(Lu5(Mn2C3)3)2Mn crystallizes in the cubic I-43m space group. The structure is three-dimensional and consists of two manganese molecules and one Lu5(Mn2C3)3 framework. In the Lu5(Mn2C3)3 framework, there are two inequivalent Lu3+ sites. In the first Lu3+ site, Lu3+ is bonded in a 8-coordinate geometry to eight C+3.11- atoms. There are four shorter (2.41 Å) and four longer (2.57 Å) Lu–C bond lengths. In the second Lu3+ site, Lu3+ is bonded to six equivalent C+3.11- atoms to form distorted corner-sharing LuC6 pentagonal pyramids. There are three shorter (2.53 Å) and three longer (2.60 Å) Lu–C bond lengths. Mn2+ is bonded in a distorted trigonal non-coplanar geometry to three C+3.11- atoms. There is two shorter (1.86 Å) and one longer (2.04 Å) Mn–C bond length. There are two inequivalent C+3.11- sites. In the first C+3.11- site, C+3.11- is bonded to four Lu3+ and two equivalent Mn2+ atoms to form a mixture of distorted edge and corner-sharing CLu4Mn2 octahedra. The corner-sharing octahedra tilt angles range from 5–68°. In the second C+3.11- site, C+3.11- is bonded in a 7-coordinate geometry to four equivalent Lu3+, two equivalent Mn2+, and one C+3.11- atom. The C–C bond length is 1.38 Å.
MnO2(CO2)2 is Cyanogen Chloride-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of eight carbon dioxide molecules and four manganese hydroxide (mn(oh)2) molecules.
Mg(O3Br2)2(MnO3)2(Br)2 crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of four hydrobromic acid molecules, four manganese;trihydrate molecules, and two Mg(O3Br2)2 clusters. In each Mg(O3Br2)2 cluster, Mg2+ is bonded in an octahedral geometry to six O2- atoms. There are four shorter (2.14 Å) and two longer (2.23 Å) Mg–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one Mg2+ and one Br2+ atom. The O–Br bond length is 1.74 Å. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to one Mg2+ and two equivalent Br2+ atoms. Both O–Br bond lengths are 2.03 Å. Br2+ is bonded in an L-shaped geometry to two O2- atoms.
The next generation of batteries requires electrolytes with high conductivity, mechanical stability, good adhesion with electrodes, wide electrochemical windows, and scalability. The present study introduces a concept of doped quasi single-ion conducting copolymers based on methacrylate-(trifluoromethanesulfonyl)imide (TFSI) and vinyl ethylene carbonate which at room temperature are mechanically robust and display ionic conductivities of ~0.1 mS/cm. These electrolytes can be polymerized/crosslinked in-situ, making them easily implementable in current battery manufacturing technologies. They also allow for switching between Li + and Na + transport using simple chemistry procedures. To demonstrate their potential for battery applications, the newly developed Li conductors have been tested in symmetric cells, exhibiting overall impedance below 350 Ohm and plating/stripping stability up to 1 mA/cm 2 . Moreover, lithium metal batteries incorporating this electrolyte and high-voltage Lithium Nickel Manganese Cobalt Oxide (NMC) cathodes show good capacity retention (~79%) during charging and discharging for 80 cycles at C/10 rate and a Coulombic efficiency close to 100% in the entire measurement range. The compositional, mechanical and electrochemical versatility of these electrolytes opens new venues for the design of polymer-based batteries capable of fast charging and extended cycle life, aligning with the current global green energy storage strategies.
Pressurized oxy-combustion (OC) is regarded as an energy-efficient alternative to atmospheric OC. To utilize the captured carbon dioxide (CO2) from pressurized OC for enhanced oil recovery or carbon storage in geological formations, the CO2 product stream must meet the required purity specifications. One major impurity in OC flue gases is residual O2 (e.g., 3 vol%). In this study, a catalytic approach has been investigated to remove the residual O2 through a reduction reaction with injected methane (CH4) in a reverse-flow fixed-bed (RFFB) reactor. The performance was tested for a supported copper (Cu)-based catalyst synthesized by incipient wetness impregnation and a cobalt-manganese (CoMn) oxide catalyst synthesized by a coprecipitation method. A commercial Cu-based catalyst was also studied as the reference. Experimental results revealed that under the reverse-flow operation, the temperature profiles in the reactor were symmetrical on both sides of the catalyst zone and were more homogenous than those under the conventional one-direction-flow operation. Among the tested catalysts, the CoMn catalyst was the most reactive for promoting the reduction of O2 with CH4, able to attain >95% O2 removal at 475 °C and a gas hourly space velocity (GHSV) of 18,000 h-1 with a feed gas containing 3 vol% O2. Under all experiments, the concentrations of carbon monoxide (CO) were lower than 30 ppmv in the effluent gas streams. The reaction between O2 and CH4 could be depicted by using the Mars–van Krevelen redox mechanism based on a two-step reduction–oxidation reaction pathway.
In this project, the relationship between natural organic matter (NOM) and two radioactive elements that are relevant to nuclear waste disposal were studied: Plutonium (Pu) and Iodine. The human and environmental risks associated with Pu stem mainly from the very long half-lives of several of its isotopes ( 238 Pu, 88 yr; 239 Pu, 24,100 yr; 240 Pu, 6560 yr) and its radiotoxicity. Understanding Pu biogeochemical behavior in both near-field (>10-11M) and far-field scales (<10-11M) is imperative to the development of approaches for reprocessing Pu, remediation of Pu contamination and accurate assessment of risks posed by disposal practices for Pu-bearing wastes. The environmental mobility of Pu can be affected by redox potential, pH, adsorption, precipitation, complexation, colloid formation, and microbial activity, of which the first characteristic has the most profound influence. Numerous studies have shown high affinity of Pu towards NOM, as well as to mineral phases. NOM is ubiquitous in the environment, e.g., both fulvic and humic acids are able to reduce Pu(V,VI) to Pu(IV) and the redox potential of NOM is positively related to the abundance of phenolic/acidic OH groups. NOM can either facilitate or limit actinide migration, depending on specific biogeochemical conditions including pH, mineral and organic matter characteristics, etc. The other radionuclide of interest is radioiodine ( 129 I). 129I is a major by-product of nuclear fission and of serious concern to the Department of Energy (DOE) as it is among the top risk drivers at existing and potential radiowaste-contaminated sites. The risk of 129 I stems largely from its high bioconcentration factor (90% of the body’s iodine is accumulated in the thyroid), a high inventory at source terms, a very long-half life (16M years), and rapid mobility in the subsurface environment. As a consequence, 129 I has the lowest drinking water standard (1 pCi/L) among all radionuclides in the Federal Register. With a novel and sensitive gas chromatography-mass spectrometry (GC-MS) method developed in our lab, it is possible to quickly and simultaneously determine the distribution of 129 I and stable 127 I forms in environments, as low as 2 pCi/L for 129 I. This method was subsequently validated using accelerator mass spectroscopy, AMS. IO 3 - and organo-I were determined as major species in the groundwater of SRS and the Hanford Site, contrary to thermodynamic predictions that I- should be the dominant species at these sites. Mobility of 129 I was also demonstrated to depend greatly on the I species and its concentration, sediment pH, and redox state, with times to achieve equilibrium taking up to 12 weeks. Along the groundwater pathway in the F-Area of SRS, 129 I- supplied from the seepage basins was transformed to 129 IO 3 - and organo- 129 I with increasing iodine sediment sorption, causing the lower total 127 I and 129 I concentrations along the gradient transect of the waste plume. By contrast, groundwater 129 I concentrations in the wetlands (as high as 1617.3 pCi/L) were greatly elevated with respect to the source term (159.3 pCi/L). While the NOM promoted the uptake of 129 I to the wetland sediment, it also promoted the formation of soluble organic fraction. A small fraction of NOM that is bound to iodine can behave as a mobile organo-I source. Iodide was enzymatically incorporated into NOM, whereas both iodide and iodate were abiotically bound to NOM, under certain conditions. Iodate removal from the mobile aqueous phase can also occur through incorporation into carbonate (e.g., at the Hanford Site, USA). Thus immobilization and re-mobilization of iodine species were influenced by pH, Eh and the presence of NOM and metal oxides, which adds to the complexity of site remediation action. A ground-breaking result was to elucidate the products (i.e. organo-iodine moieties formed via enzymatic and non-enzymatic processes) at the molecular level by nuclear magnetic resonance (NMR) and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS). We found that iodine-NOM interactions may be influenced by NOM hydrophobic aliphatic moieties. From the perspective of ESI-FTICRMS, organo-iodine formulas were ascribed to the groups of unsaturated hydrocarbons, lignins and proteins. Iodate is likely abiotically reduced to reactive iodine species by lignin- and tannin-like compounds or carboxylic-rich alicyclic molecules (CRAM). We also investigated microbial mechanisms in iodine incorporation into NOM. We established that soil bacteria isolated from F-Area of SRS did not accumulate significant amounts of I- (0.2-2%). Intracellular uptake of I- decreases with increasing pH when pH ranged from 4 to 6. In contrast, 44 out of 84 strains isolated from the F-Area of SRS can transform I- to IO 3 - and organo-iodine. In some cases, oxidation was facilitated in the presence of H 2 O 2 . Microbes can also excrete organic acids that enhance I- oxidation by lowering the ambient pH and reacting with H 2 O 2 to form peroxy carboxylic acids. At lower pH values (≤5), H 2 O 2 hydrolysis was the driving force for iodide-oxidation; whereas, at pH ≥ 6, spontaneous decomposition of peroxy carboxylic acids, originating from H 2 O 2 and organic acids were the primary cause of iodide oxidation. Lastly, it was determined that microbial processes involved in Mn (II) are capable of directly oxidizing I- via enzymatic catalysis (i.e., multicopper oxidases), or indirectly through the formation of reactive oxygen species (ROS) and/or biogenic manganese oxides. ROS-mediated oxidation of I- was found to predominate at pH >5, whereas the enzymatic and Mn oxide pathways were more active at pH < 5. Together, this project has resulted in 9 publications in high-impact journals, and the training of 1 Ph.D and 4 undergraduate students.