Biomass photorefinery is an ideal concept to help alleviate the current energy crisis and move toward carbon neutrality. Nevertheless, limited by the complex structure and multiple functional groups of biomass and its derivatives, current biomass photorefinery still suffers from inefficient substrate conversion and product selectivity. In this work, we rationally design polymeric carbon nitride (CN) by supramolecular self-assembly coupled with an organic copolymerization process method to convert glucose, a widely used model biomass molecule, into glycerol which is a value-added photorefinery product. This molecularly engineered photocatalyst improves the charge separation efficiency and significantly enhances visible light absorption. Importantly, ∼95% glucose conversion is achieved by the photogenerated reactive species of •O2 –, h+, and •OH under mild conditions with selective C3–C4 cleavage via a retro-aldol reaction pathway. The presence of O2 could provide favorable reactive oxygen species during the photoreforming process, and glycerol is the main product with >50% selectivity under the effect of nucleophilic dimethyl sulfoxide (DMSO), which realizes the hydrogenation reaction of 1,3-dihydroxyacetone (DHA) and glyceraldehyde. Our density functional theory (DFT) analysis reveals that DHA is the more favored intermediate compared to glyceraldehyde. This work demonstrates an example of using engineered photocatalysts and reaction systems for selective biomass valorization into biofuels/chemicals via a mild photocatalytic process.
Herein, the crystal structures and physical properties of two previously unreported barium seleno-germanates, Ba 6 Ge 2 Se 12 and Ba 7 Ge 2 Se 17 , are presented. Ba 6 Ge 2 Se 12 adopts the P2 1 /c space group with a = 10.0903(2) Å, b = 9.3640(2) Å, c = 25.7643(5) Å, and β = 90.303(1)°, whereas Ba 7 Ge 2 Se 17 crystallizes in the Pnma space group with a = 12.652(1) Å, b = 20.069(2) Å, c = 12.3067(9) Å. Both structures feature polyatomic anion disorder: [Se 2 ] 2− in the case of Ba 6 Ge 2 Se 12 and [GeSe 5 ] 4− in the case of Ba 7 Ge 2 Se 17 . The anion disorder is verified by comparing pair distribution functions of ordered and disordered models of the structures. These anions are split unevenly across two possible sets of atomic coordinates. The optical band gaps obtained from the powdered samples are found to be 1.75 and 1.51 eV for Ba 6 Ge 2 Se 12 and Ba 7 Ge 2 Se 17 , respectively. Differential scanning calorimetry experiments indicate that the compounds are stable under the exclusion of air up to at least 673 K. The thermal diffusivity measurements revealed thermal conductivities reaching values as low as 0.33 W m −1 K −1 in both compounds at 573 K.
We present the synthesis and physical properties of a new breathing pyrochlore magnet CuAlCr4S8 via synchrotron x-ray diffraction (XRD), magnetization under ambient and applied hydrostatic pressure, heat capacity, and muon spin relaxation/rotation (µSR) measurements. CuAlCr4S8 exhibits positive thermal expansion with concave upward temperature dependence. We observed a sharp antiferromagnetic ordering transition of a purely magnetic nature at 20 K, which shifts by as much as 3.2 K on application of 600 MPa pressure. The breathing factor (B f = J /J) in breathing pyrochlores can be an important parameter to tune the magnetic ground states of the pyrochlore lattice. The breathing factor can be modulated through breathing ratio, the ratio of sizes of the two tetrahedra, by using different elements at A and A' sites in the breathing pyrochlore structure. We find that CuAlCr4S8 has a breathing ratio of 1.0663(8), which is comparable to other sulfur breathing pyrochlores.
A new solid solution (1−x)Bi(Fe2/8Ti3/8Mg3/8)O3–(x)PbTiO3 (BFTM‐PT) is synthesized and the electromechanical properties are measured. This system is defined as a low‐lead material with ferroelectric/piezoelectric behavior and a morphotropic phase boundary (MPB) that leads to enhanced properties. The MPB is located between x = 0.30 and 0.35 and coincides with a structural phase transition and a sharp increase in the piezoelectric response. The system demonstrates ferroelectric hysteresis where x = 0.325 displays the best properties with a maximum polarization of 39 µC cm−2 and a remnant polarization of 26 µC cm−2. The range of compositions has high Curie temperature (Tc), ranging from 625–650 °C. Materials with a Tc above 400 °C typically have a low d33 of <50 pC N−1 at room temperature. However, BFTM‐PT has a higher d33 that most other compositions with a Tc in this range, with the highest being 145 pC N−1 for x = 0.375. The d33 drops off above 100 °C, but doping studies can be done in the future to stabilize the piezoelectric response at higher temperatures. These outstanding properties open the possibility of new transducer applications, in particular ones requiring high temperature and high power.
Typically, quantum spin liquid candidates can be found in materials with a combination of geometrical frustration along with low spin. Due to its spin of S = 1/2 the copper (II) ion is often present in the discussion on spin liquid candidates. The solid state compound Ca 3 Cu 2 GeV 2 O 12 is a material that crystallizes in the garnet structure (s.g. #230, Ia3d), where 3D frustration is known to occur. Heat capacity has shown a lack of magnetic ordering down to 0.35 K, confirmed with low temperature neutron diffraction to 0.07 K. This system displays a Weiss temperature of −0.93(1) K indicating net antiferromagnetic interactions and significant J 1 -J 2 competition causing frustration. Using both neutron and xray diffraction along with heat capacity and magnetometry, the work presented here shows Ca 3 Cu 2 GeV 2 O 12 has potential as a new spin liquid candidate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.