@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 CO2}, 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{mcguigan_fosu_2024, title={Defects orchestrate concerted CO2 catalysis}, ISSN={["2397-3358"]}, DOI={10.1038/s41570-024-00621-2}, journal={NATURE REVIEWS CHEMISTRY}, author={McGuigan, Scott and Fosu, Emmanuel Adu}, 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{mcguigan_tereniak_donley_smith_jeon_zhao_sampaio_pauly_keller_collins_et al._2023, title={Discovery of a Hybrid System for Photocatalytic CO2 Reduction via Attachment of a Molecular Cobalt-Quaterpyridine Complex to a Crystalline Carbon Nitride}, volume={10}, ISSN={["2574-0962"]}, DOI={10.1021/acsaem.3c01670}, abstractNote={While recent reports have demonstrated the attachment of molecular catalysts to amorphous, graphitic carbon nitrides (g-CN) for light-driven CO2 reduction, approaches to the utilization of crystalline carbon nitrides have remained undiscovered. Herein, a functional hybrid photocatalyst system has been found using a crystalline carbon nitride semiconductor, poly(triazine imide) lithium chloride (PTI-LiCl), with a surface-attached CoCl2(qpy-Ph-COOH) catalyst for CO2 reduction. The molecular catalyst attaches to PTI-LiCl at concentrations from 0.10 to 4.30 wt % and exhibits ∼96% selectivity for CO production in a CO2-saturated, aqueous 0.5 M KHCO3 solution. Optimal loadings were found to be within 0.42–1.04 wt % with rates between 1,400 and 1,550 μmol CO/g·h at an irradiance of 172 mW/cm2 (λ = 390 nm) and apparent quantum yields of ∼2%. This optimized loading is postulated to represent a balance between maximal turnover frequency (TOF; 300+ h–1) and excess catalyst that can limit excited-electron lifetimes, as probed via transient absorption spectroscopy. An increase in the incident irradiance yields a concomitant increase in the TOFs and CO rates only for the higher catalyst loadings, reaching up to 2,149 μmol CO/g·h with a more efficient use of the catalyst surface capacity. The lower catalyst loadings, by comparison, already function at maximal TOFs. Higher surface loadings are also found to help mitigate deactivation of the molecular catalysts during extended catalytic testing (>24 h) owing to the greater net surface capacity for CO2 reduction, thus representing an effective strategy to extend lifetime. The hybrid particles can be deposited onto an FTO substrate to yield ∼60% Faradaic efficiency for photoelectrochemical CO production at −1.2 V vs Ag/AgCl bias. In summary, these results demonstrate the synergistic combination of a crystalline carbon nitride with a molecular catalyst that achieves among the highest known rates in carbon-nitride systems for the light-driven CO2 reduction to CO in aqueous solution with >95% selectivity.}, journal={ACS APPLIED ENERGY MATERIALS}, author={McGuigan, Scott and Tereniak, Stephen J. and Donley, Carrie L. and Smith, Avery and Jeon, Sungho and Zhao, Fengyi and Sampaio, Renato N. and Pauly, Magnus and Keller, Landon and Collins, Leonard and et al.}, year={2023}, month={Oct} } @article{genoux_pauly_rooney_choi_shang_mcguigan_fataftah_kayser_suhr_debeer_et al._2023, title={Well-Defined Iron Sites in Crystalline Carbon Nitride}, volume={145}, ISSN={["1520-5126"]}, DOI={10.1021/jacs.3c05417}, abstractNote={Carbon nitride materials can be hosts for transition metal sites, but Mössbauer studies on iron complexes in carbon nitrides have always shown a mixture of environments and oxidation states. Here we describe the synthesis and characterization of a crystalline carbon nitride with stoichiometric iron sites that all have the same environment. The material (formula C6N9H2Fe0.4Li1.2Cl, abbreviated PTI/FeCl2) is derived from reacting poly(triazine imide)·LiCl (PTI/LiCl) with a low-melting FeCl2/KCl flux, followed by anaerobic rinsing with methanol. X-ray diffraction, X-ray absorption and Mössbauer spectroscopies, and SQUID magnetometry indicate that there are tetrahedral high-spin iron(II) sites throughout the material, all having the same geometry. The material is active for electrocatalytic nitrate reduction to ammonia, with a production rate of ca. 0.1 mmol cm-2 h-1 and Faradaic efficiency of ca. 80% at -0.80 V vs RHE.}, number={38}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Genoux, Alexandre and Pauly, Magnus and Rooney, Conor L. and Choi, Chungseok and Shang, Bo and McGuigan, Scott and Fataftah, Majed S. and Kayser, Yves and Suhr, Simon C. B. and Debeer, Serena and et al.}, year={2023}, month={Sep}, pages={20739–20744} }