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By shortening the previous shortest tetracarboxylate ligand, the first ligand-to-ligand and axial-to-axial pillaring method was realized in the prototype MOF

The metal-organic framework (MOF) NTUniv-54 (NTUniv = Nantong University) was assembled via utilizing click chemistry with densely decorated trizole units and exposed metal sites, which exhibited the best methane working ability (197 cm3·cm-3 from 100 to 5 bar and 177 cm3·cm-3 from 65 to 5 bar at 298 K), and the lowest CO2Qst of 22.8 kJ·mol-1 in all triazole-MOFs at room temperature.

Facile synthesis of cost-effective carbon-supported Co single atoms (Co-SAs) exhibits huge potential applications in energy storage and conversion devices. We here report the implantation of Co-SAs into hollow carbon spheres (Co-SAs-HCS) via a facile wet-chemistry strategy followed by controlled pyrolysis. Electron-rich histidine acted as a Lewis base effectively immobilizing Co2+ (Lewis acid) via the electrostatic effect and hydrogen bonds, thus achieving the scalable synthesis of Co-SAs-HCS. We constructed a series of histidine-Co2+ structure models to elucidate the formation of histidine-Co2+ complexes by analyzing their binding energy. X-ray absorption fine-structure results verify that central Co atoms with four N coordination atoms possess a non-planar Co-N4 structure. Electrochemical results indicate that the as-prepared Co-SAs-HCS catalyst shows a low potential difference (0.809 V) between the oxygen evolution reaction potential at 10 mA cm-2 and the oxygen reduction reaction half-wave potential, outperforming the commercial Pt/C catalysts (0.996 V). Moreover, an assembled Zn-air battery based on Co-SAs-HCS exhibits an unexpected long-term durability. We have demonstrated that non-planar Co-N4-1-O2 sites are the source for highly efficient adsorption and dissociation of O2 molecules and then reduction of the free energy of desorption of the intermediates by density functional theory. Our findings provide a new design insight into the exploration of advanced electrocatalysts, which will be applied in the design of green energy devices in the future.

By systematic ligand tuning for control of the secondary building units, the use of tridentate carboxylic acid to construct the rod scandium metal-organic framework NTUniv-55 (NTUniv = Nantong University) with high chemical stability and interesting selective gas adsorption was reported.

Oxygen vacancy (VO) formation energy and its migration barrier are two determining factors for the effectiveness of solid electrolytes (SEs) in solid oxide fuel cells (SOFCs). In this work, a serie...

The A-site ordered negative thermal expansion material LaCu3Fe4O12 (LaCFO) was comprehensively investigated by using first-principles calculations. A pressure-triggered crystal structural phase transition from space group Im3 (No. 204) to Pn3 (No. 201) and magnetic transformation from a G-type antiferromagnetic (G_AFM) ground state to ferrimagnetic (FerriM) coupling were observed in LaCFO via gradual compression of the equilibrium volume. Correspondingly, the Fe–Cu intersite charge transfer from Fe to Cu 3dxy orbital, expressed as 4Fe3+ + 3Cu3+ → 4Fe3.75+ + 3Cu2+, was simulated along with the magnetic phase transformation from the G_AFM configuration to the FerriM state. Intriguingly, the Fe charge disproportionation, formulated as 8Fe3.75+ → 5Fe3+ + 3Fe5+, appeared and was attributed to the strong hybridization between Fe 3d and O 2p orbitals in the FerriM state when the volumes were substantially compressed up to less than or equal to 80%V. Meanwhile, the external hydrostatic pressure also leads to a ...

BaLaGa3O7:Nd (BLGO:Nd) has been investigated as a laser crystal material for about three decades. In the present work, the luminescence mechanism of BLGO:Nd is clarified by density functional theory (DFT) calculations. Structural optimization was first performed on the constructed supercell to obtain the equilibrium geometry. On the basis of the optimized crystal, the electronic structures of the BLGO host (without and with single defects) and the BLGO:Nd phosphor (without and with neighboring defects) were comprehensively investigated. Three important features are revealed by theoretical analyses. First, single defects in BLGO have little effect on the light emission, although the impurity levels appeared within the band gap. Second, luminescence can be realized by the introduction of Nd ions. Calculations of optical properties demonstrated that parity-forbidden transitions among the 4f levels are partially allowed because the mixing of 4f and 5d configurations occurs at higher empty 4f levels. It is thus clear that the electronic transitions between occupied 4f and empty 4f-5d states are electric-dipole-allowed. Therefore, light emission in BLGO:Nd can be achieved in the electronic transition process of Nd 4f electrons → empty 4f-5d levels → empty 5d levels → Nd 4f levels. The neighboring intrinsic defects play only an auxiliary role in prolonging the decay time. Third, co-doping of Tb in BLGO:Nd is considered to be beneficial to luminescence in theory because of its shallow to deep distribution of impurity orbitals in the band gap. Therefore, BLGO:Nd co-doped with other lanthanide ions will offer guidelines in the search for the best luminescent materials.

The A-site ordered negative thermal expansion material LaCu