@article{pauly_white_deegbey_fosu_keller_mcguigan_dianat_gabilondo_wong_murphey_et al._2024, title={Coordination of copper within a crystalline carbon nitride and its catalytic reduction of CO<sub>2</sub>}, volume={3}, ISSN={["1477-9234"]}, DOI={10.1039/d4dt00359d}, abstractNote={Crystallites of Cu-coordinated poly(triazine imide) were synthesized by flux methods and deposited from particle suspensions onto electrodes, yielding sizable current densities for the electrocatalytic reduction of CO2.}, journal={DALTON TRANSACTIONS}, author={Pauly, Magnus and White, Ethan and Deegbey, Mawuli and Fosu, Emmanuel Adu and Keller, Landon and Mcguigan, Scott and Dianat, Golnaz and Gabilondo, Eric and Wong, Jian Cheng and Murphey, Corban G. E. and et al.}, year={2024}, month={Mar} }
 @article{broughton_o'donnell_gabilondo_newell_maggard_jones_2024, title={Superstructure reflections in 40% Sn(II)-substituted BaZr<sub>0.5</sub>Ti<sub>0.5</sub>O<sub>3</sub> perovskite modeled with a Bayesian method for crystallographic refinement}, volume={6}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-024-09878-w}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Broughton, Rachel and O'Donnell, Shaun and Gabilondo, Eric and Newell, Ryan and Maggard, Paul A. and Jones, Jacob L.}, year={2024}, month={Jun} }
 @article{jana_gabilondo_mcguigan_maggard_2024, title={Syntheses, Crystal Structures, and Electronic Structures of Quaternary Group IV-Selenide Semiconductors}, volume={3}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.4c00363}, abstractNote={Early transition-metal chalcogenides have garnered recent attention for their optoelectronic properties for solar energy conversion. Herein, the first Zr-/Hf-chalcogenides with a main group cation, Ba9Hf3Sn2Se19 (1) and Ba8Zr2SnSe13(Se2) (2), have been synthesized. The structure of 1 is formed from isolated SnSe44- tetrahedra and distorted HfSe6 octahedra. The latter condense via face-sharing trimeric motifs that are further vertex-bridged into chains of 1∞[Hf(1)2Hf(2)Se11]10-. The structure of 2 is comprised of SnSe44- tetrahedra, Se22- dimers, and face-sharing dimers of distorted ZrSe6 octahedra. These represent the first reported examples of Hf-/Zr-chalcogenides exhibiting face-sharing octahedra with relatively short Hf-Hf and Zr-Zr distances. Their preparation in high purity is inhibited by their low thermodynamic stability, with calculations showing small calculated ΔUdec values of +7 and +9 meV atom-1 for 1 and 2, respectively. Diffuse reflectance measurements confirm the semiconducting nature of 1 with an indirect band gap of ∼1.4(1) eV. Electronic structure calculations show that the band gap absorptions arise from transitions between predominantly Se-4p valence bands and mixed Hf-5d/Sn-5p or Zr-4d/Sn-5p conduction bands. Optical absorption coefficients were calculated to be more than ∼105 cm-1 at greater than 1.8 eV. Thus, promising optical properties are demonstrated for solar energy conversion within these synthetically challenging chemical systems.}, journal={INORGANIC CHEMISTRY}, author={Jana, Subhendu and Gabilondo, Eric and McGuigan, Scott and Maggard, Paul A.}, year={2024}, month={Mar} }
 @article{jana_gabilondo_maggard_2024, title={Two new multinary chalcogenides with (Se<sub>2</sub>)<SUP>2-</SUP> dimers: Ba<sub>8</sub>Hf<sub>2</sub>Se<sub>11</sub>(Se<sub>2</sub>) and Ba<sub>9</sub>Hf<sub>3</sub>Se<sub>14</sub>(Se<sub>2</sub>)}, volume={329}, ISSN={["1095-726X"]}, DOI={10.1016/j.jssc.2023.124376}, abstractNote={Two multinary selenides, Ba8Hf2Se11(Se2) and Ba9Hf3Se14(Se2), with unprecedented structure types have been prepared using high-temperature synthesis techniques and represent the first known compounds in the Ba-Hf-Se system. Their structures were determined from single crystal X-ray diffraction (XRD) data. The Ba8Hf2Se11(Se2) compound crystallizes in the monoclinic C2/c space group with a = 12.3962(15) Å, b = 12.8928(15) Å, c = 18.1768(17) Å, and β = 90.685(4)°, while Ba9Hf3Se14(Se2) forms in the rhombohedral R3‾ space group with a = b = 19.4907(6) Å and c = 23.6407(11) Å. Both have pseudo-zero-dimensional structures with homoatomic Se–Se bonding in the form of (Se2)2− at distances of 2.400–2.402 Å. The structure of Ba8Hf2Se11(Se2) is comprised of [Hf2Se11]14−, Ba2+, and (Se2)2− dimers. Conversely, the Ba9Hf3Se14(Se2) structure contains a novel perovskite-type cluster constructed from eight octahedrally-coordinated Hf cations, i.e., [Hf8Se36]40−, and isolated [HfSe6]8− units which are separated by (Se2)2− dimers and Ba2+ cations. Polycrystalline Ba8Hf2Se11(Se2) is synthesized at 1073 K using a two-step solid-state synthesis method, with the co-formation of a small amount of a BaSe secondary phase. A direct bandgap of 2.2(2) eV is obtained for the polycrystalline sample of Ba8Hf2Se11(Se2), which is consistent with its yellow color. Density functional theory calculations reveal their bandgap transitions stem from predominantly filled Se-4p to empty Hf-5d at the edges of the valence bands (VB) and conduction bands (CB), respectively. The optical absorption coefficients are calculated to be relatively large, exceeding ∼105 cm−1 at about >2.0 eV with effective masses in the CB varying from ∼0.5 me (Γ → A) in Ba8Hf2Se11(Se2) to ∼1.0 me (Γ → L) in Ba9Hf3Se14(Se2). Thus, their optoelectronic properties are shown to be competitive with existing perovskite-type chalcogenides that have been a focus of recent research efforts.}, journal={JOURNAL OF SOLID STATE CHEMISTRY}, author={Jana, Subhendu and Gabilondo, Eric A. and Maggard, Paul A.}, year={2024}, month={Jan} }
 @article{gabilondo_odonnell_jana_broughton_liang_koldemir_reichling_campbell_halasyamani_poettgen_et al._2024, title={Unveiling Stability Factors in Sn(II)-Containing Oxides: Discovery of a Polar Tin Titanate and Photocatalytic Activity for Overall Water Splitting}, volume={5}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.4c00929}, abstractNote={The discovery of Sn(II)-containing oxide semiconductors has been severely limited by a lack of understanding of the factors leading to their thermodynamic stability, e.g., chemical compositions and structure types, as well as by the absence of productive synthetic routes. The relatively few reported Sn(II)–O–M (M = early transition-metal cation) semiconductors frequently decompose at moderate to low temperatures. Herein, a large-scale predictive modeling approach was used to assess the structural factors yielding their enhanced thermodynamic stability. This has resulted in 10 new predicted Sn(II)-containing oxides that are proposed to fall within reasonable synthetic limits. Increasing stability was found for structures possessing lower Sn(II)/M ratios and local asymmetric coordination environments allowing the expression of the Sn(II) stereoactive lone pair. As a test of these results, synthetic efforts to prepare one of the proposed compounds starting from BaLa4Ti4O15 yielded the predicted layered-perovskite SnLa4Ti4O15 (SLTO). The new SLTO crystallizes in the noncentrosymmetric and polar P3c1 space group (no. 158) as confirmed by Rietveld refinements of powder X-ray diffraction (XRD) data and second harmonic generation activity. Full Sn(II) substitution was confirmed by a combination of XRD structural refinements, 119Sn Mössbauer spectroscopy, SEM-EDS, and X-ray photoelectron spectroscopy. UV–vis diffuse reflectance data confirmed that SLTO has a visible-light absorbing band gap of ∼2.4 eV and is a promising photocatalyst for solar energy conversion. After loading its surfaces with a Rh/Cr2O3–CoOx dual-cocatalyst, SLTO with hexagonal plate-shaped morphologies showed activity for overall water splitting at a rate of ∼317 μmol g–1 h–1 H2 and an apparent quantum yield of ∼22%. Thus, these results highlight the synergistic combination of chemical intuition, predictive modeling, and synthetic design in the synthesis of new Sn(II)-containing semiconductors for promising applications of their optical properties and photocatalytic activities for water splitting.}, journal={CHEMISTRY OF MATERIALS}, author={Gabilondo, Eric A. and ODonnell, Shaun and Jana, Subhendu and Broughton, Rachel and Liang, Mingli and Koldemir, Aylin and Reichling, Jack and Campbell, Carson and Halasyamani, P. Shiv and Poettgen, Rainer and et al.}, year={2024}, month={May} }
 @article{o'donnell_gabilondo_jana_koldemir_block_whangbo_kremer_pottgen_maggard_2023, title={Cation exchange route to a Eu(II)-containing tantalum oxide}, volume={328}, ISSN={["1095-726X"]}, DOI={10.1016/j.jssc.2023.124338}, abstractNote={Traditional synthetic efforts to prepare Eu(II)-containing oxides have principally involved the use of high temperature reactions starting from EuO or a controlled, highly-reducing, atmosphere. Conversely, chimie douce approaches that are more amenable to the targeted syntheses of new, and potentially metastable, Eu(II)-oxides have yet to be explored. Herein, a cation-exchange route to new Eu(II)-containing oxides, e.g., EuTa4-xO11 (x = 0.04), has been discovered and its structure determined by powder X-ray diffraction (Space group P6322 (#182), a = 6.2539(2) Å; c = 12.3417(2) Å). The compound derives from the cation exchange of Na2Ta4O11, via a reaction with EuBr2 at 1173 K, and replacement by half the number of divalent Eu cations. Rietveld refinements show preferential ordering of the Eu cations over one of the two possible cation sites, i.e., Wyckoff site 2d (∼94%; Eu1) versus 2b (∼6%; Eu2). Total energy calculations confirm an energetic preference of the Eu cation in the 2d site. Tantalum vacancies of ∼1% occur within the layer of Eu cations and TaO6 octahedra, and ∼20% partial oxidation of Eu(II) to Eu(III) cations from charge balance considerations. 151Eu Mössbauer spectroscopy measured at 78 K found a Eu(II):Eu(III) ratio of 69:31, with a relatively broad line width of the former signal of Γ = 7.6(2) mm s–1. Also, the temperature-dependent magnetic susceptibility could be fitted to a Curie Weiss expression, giving a μeff = 6.2 μB and θCW = −10 K and confirming a mixture of Eu(II)/Eu(III) cations. The optical bandgap of EuTa4-xO11 was found to be ∼1.5 eV (indirect), significantly redshifted as compared to ∼4.1 eV for Na2Ta4O11. Spin-polarized electronic structure calculations show that this redshift stems from the addition of Eu 4f7 states as a higher-energy valence band. Thus, these results demonstrate a new cation-exchange approach that represents a useful synthetic pathway to new Eu(II)-containing oxides for tunable magnetic and optical properties.}, journal={JOURNAL OF SOLID STATE CHEMISTRY}, author={O'Donnell, Shaun and Gabilondo, Eric and Jana, Subhendu and Koldemir, Aylin and Block, Theresa and Whangbo, Myung-Hwan and Kremer, Reinhard and Pottgen, Rainer and Maggard, Paul A.}, year={2023}, month={Dec} }
 @article{gabilondo_newell_broughton_koldemir_poettgen_jones_maggard_2023, title={Switching Lead for Tin in PbHfO<sub>3</sub>: Noncubic Structure of SnHfO<sub>3</sub>}, volume={9}, ISSN={["1521-3773"]}, DOI={10.1002/anie.202312130}, abstractNote={Abstract}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Gabilondo, Eric A. and Newell, Ryan J. and Broughton, Rachel and Koldemir, Aylin and Poettgen, Rainer and Jones, Jacob L. and Maggard, Paul A.}, year={2023}, month={Sep} }
 @article{gabilondo_newell_chestnut_weng_jones_maggard_2022, title={Circumventing thermodynamics to synthesize highly metastable perovskites: nano eggshells of SnHfO3}, volume={11}, ISSN={["2516-0230"]}, DOI={10.1039/d2na00603k}, abstractNote={Through a multifaceted synthetic technique and leveraging surface diffusion, a new Sn(ii)-perovskite, SnHfO3, has been synthesized as nano eggshells for the first time.}, journal={NANOSCALE ADVANCES}, author={Gabilondo, Eric A. and Newell, Ryan J. and Chestnut, Jessica and Weng, James and Jones, Jacob L. and Maggard, Paul A.}, year={2022}, month={Nov} }
 @article{gabilondo_o'donnell_newell_broughton_mateus_jones_maggard_2022, title={Renaissance of Topotactic Ion-Exchange for Functional Solids with Close Packed Structures}, volume={4}, ISSN={["1521-3765"]}, DOI={10.1002/chem.202200479}, abstractNote={Abstract}, journal={CHEMISTRY-A EUROPEAN JOURNAL}, author={Gabilondo, Eric and O'Donnell, Shaun and Newell, Ryan and Broughton, Rachel and Mateus, Marcelo and Jones, Jacob L. and Maggard, Paul A.}, year={2022}, month={Apr} }
 @article{gabilondo_o'donnell_broughton_jones_maggard_2021, title={Synthesis and stability of Sn(II)-containing perovskites: (Ba,Sn-II)(HfO3)-O-IV versus (Ba,Sn-II)(SnO3)-O-IV}, volume={302}, ISSN={["1095-726X"]}, DOI={10.1016/j.jssc.2021.122419}, abstractNote={While Sn(II)-containing perovskite oxides have long drawn attention as Pb(II) substitutes in technologically-relevant dielectric materials, they are also highly thermodynamically unstable and potentially impossible to prepare. Investigations into the new flux-mediated syntheses of metastable Sn(II)-containing hafnate and stannate perovskites were aimed at understanding the key factors related to their synthesizability. The BaHfO3 perovskite was reacted with SnClF from 250 to 350 ​°C for 12–72 ​h, yielding an unprecedented Sn(II) concentration on the A-site of up to ~70 ​mol%, i.e., (Ba0.3Sn0.7)HfO3 in high purity. Elemental mapping using EDS shows the Sn(II) cations diffuse gradually throughout the crystallites, with two reaction cycles needed to give a nearly homogeneous distribution. In contrast, similar reactions with BaSnO3 and as little as 10 ​mol% Sn(II) result in decomposition to SnO, SnO2, and BaSnO3. The (Ba1-xSnx)HfO3 compositions exhibit a primary cubic perovskite structure (Pm3¯m; for x ​= ​1/3, 1/2 and 2/3) by powder X-ray diffraction (XRD) methods, with the Sn(II) cations substituted on the A-site. Total energy calculations show the thermodynamic instability versus the ground state (i.e., metastability) for (Ba1-xSnx)HfO3 increases with Sn(II) substitution, reaching a maximum of ~446 ​meV atom−1 at ~70 ​mol% Sn(II). The decomposition pathway of (Ba1/3Sn2/3)HfO3 was probed by ex situ XRD as well as in situ electron microscopy methods. An onset of thermally-induced decomposition begins at ~350–400 ​°C to give the more stable oxides which are found to segregate out in surface layers. These results help to elucidate the factors underpinning the synthesizability of highly metastable Sn(II)-containing perovskites, which increases with their cohesive energy and with the absence of lower-energy polymorphs or other ground states that can be reached without significant ion diffusion.}, journal={JOURNAL OF SOLID STATE CHEMISTRY}, author={Gabilondo, Eric A. and O'Donnell, Shaun and Broughton, Rachel and Jones, Jacob L. and Maggard, Paul A.}, year={2021}, month={Oct} }