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To avoid the agglomeration of iron NPs and improve the dispersion of Fe SAs, we employed a mixed-ligand strategy to regulate the iron content in PCN-224(ZnxFey) and PCN-222(ZnxFey). Thanks to the sublimation of Zn and the Kirkendall effect, uniform dispersions of Fe SAs with 1.04–1.06 wt% were obtained in the pyrolysis products Zn0.5Fe0.5–N–C-224 and Zn0.5Fe0.5–N–C-222 with excellent CO2 → CO activity, super-stability, and recyclability. [ABSTRACT FROM AUTHOR]

Molecular complexes with active metal centers exhibit high activity and selectivity for electrochemical CO2 reduction reaction (CO2RR), which represents a promising method for transforming greenhouse gas into valuable chemicals and feedstock. Using metal–organic frameworks (MOFs) to load the active molecular complexes then employing the combination with the carbonic conducting material may exhibit a beneficial effect for CO2RR. Herein, we obtained a composite catalyst named PCN-222(Fe)/CNTs, which was in situ synthesized through the solvothermal method that loads iron porphyrin-centered PCN-222(Fe) molecules onto CNTs. The catalyst PCN-222(Fe)/CNTs exhibits excellent electrocatalytic performance for CO2RR with a FECO of 95.5% (m(Fe-TCPP):m(CNTs) = 1:30, written as PCN-222(Fe)/CNTs-30) and an overpotential (η) of 494 mV. In addition, the turnover frequency (TOF) is high as 448.76 h−1 (3.011 site−1 s−1) and the hydrogen evolution reaction (HER) is indistinctive. After long-term electrocatalysis of 10 h at −0.6 V vs. RHE, PCN-222(Fe)/CNTs-30 remained its high catalytic performance with average FECO = 90%. This work provides a solid foundation for further research in the high-efficiency transformation of CO2 to CO. [ABSTRACT FROM AUTHOR]

The eCO2RR activity is correlated to the internal structural character of the catalyst. We employed two types of structural models of porphyrin-based MOFs of PCN-222(Cu) and PCN-224(Cu) into heterogeneous catalysis to illustrate the effect of structural factors on the eCO2RR performance. The composite catalyst PCN-222(Cu)/C displays better activity and selectivity (η = 450 mV, FEHCOOH = 44.3%, j = 3.2 mA cm−2) than PCN-224(Cu)/C (η = 450 mV, FEHCOOH = 34.1%, j = 2.4 mA cm−2) for the CO2 reduction to HCOOH in the range of −0.7–−0.9 V (vs. RHE) due to its higher BET surface area, CO2 uptake, and a larger pore diameter. It is interesting that PCN-224(Cu)/C displays better performance in the range of −0.4–−0.6 V (vs. RHE) due to its greater heat of adsorption, Qst and a higher affinity for CO2 molecule, which could promote the capture of CO2 onto the exposed active sites. As a result, PCN-224(Cu)/C exhibits better stability for the long-term electrolysis. [ABSTRACT FROM AUTHOR]

Using the methodology of extension of reduced transition metal-grafted ε-Keggin polyoxoanions with two types of terphenyl-based tricarboxylates of H3L1 (3,5′,3′′-position substitution) and H3L2 (4,5′,4′′-position substitution) we isolated two (3,6)-connected 3D polyoxometalate-based metal–organic frameworks, [TBA]3[H3PMo12O40][Zn4L2] (1, YZU-105), and [TPA]3[H3PMo12O40][Zn4L1]·0.5H2O (2, YZU-106) (H3L1 = [1,1′;3′,1′′-terphenyl]-3,5′,3′′-tricarboxylic acid; H3L2 = [1,1′;3′,1′′-terphenyl]-4,5′,4′′-tricarboxylic acid; TBA = tetrabutylammonium; TPA = tetrapropylammonium). In both compounds, the building block was the dimerized form of Zn4-{ε-H3PMo12O40}. Such dimerization left six anchoring points for each dimer and, as a result, a 6-connected node was formed. Compounds 1 and 2 exhibited topologies of (4·85)3(4·82)6 and (65·10)3(63)6, respectively. This work illustrates that use of tri-carboxylate substitutions in different positions (3,5′,3′′-position/4,5′,4′′-position) in tripodal terphenyl-based ligands allows different extents of twisting of the peripheral aromatic ring with respect to the central ring, thereby giving rise to different extending directions and symmetries. [ABSTRACT FROM AUTHOR]

Reaction of 2-C5H4 NCOSPh, generated from 2-C5H4NCO2H and PhSH in the presence of DCC, with Fe3(CO)12affords (μ-κ2C,N-2-C5H4N)(μ-PhS)Fe2(CO)6(1) and (μ-PhS)2Fe2(CO)6(2). Reaction of (NC)2C=C(SMe)2, formed from NCCH2CN, CS2, and MeI in the presence of NaOH, with Fe3(CO)12provides (μ-κ2C,S-(NC)2C=CSMe)(μ-MeS)Fe2(CO)6(3) and (μ-MeS)2Fe2(CO)6(4). All complexes have been fully characterized by EA, IR,1H NMR, and13C NMR spectroscopy and structurally determined by X-ray crystallography. In1and3, the group attached to the bridging S is at the equatorial position. In2, two phenyl groups are at equatorial positions. Two isomers of4, ae-4 and ee-4, can be separated by thin-layer chromatography. DFT calculations reveal that the Gibbs energy difference between ae-4and ee-4is −2.17 kcal mol−1in THF and −2.29 kcal mol−1in benzene, and the isomerization barrier between ae-4and ee-4is 14.92 kcal mol−1in THF and 16.84 kcal mol−1in benzene. All these results suggest that ae-4is more stable than ee-4in either THF or benzene, and the two isomers do not interconvert. Electrochemical studies of1and3demonstrate that using HOAc as a proton source1and3can catalyze H2production. [ABSTRACT FROM AUTHOR]

A significant reduction of electromagnetic interference (EMI) for a fine-motion control rod drive (FMCRD) in a nuclear reactor is presented in this paper. A reactor design with the FMCRD can achieve high performance. However, the FMCRD produces electromagnetic noise, which affects the startup-range neutron monitoring (SRNM) system. Moreover, because the FMCRD and the SRNM system are arranged near each other under a reactor vessel, the SRNM unit is influenced by the FMCRD electromagnetic noise, leading to uncertain monitoring results and system alarms. Strong EMI could even result in a system trip. To alleviate the EMI, a grounded metal sheet is wrapped around the FMCRD cable, partially shielding it from radiation. To further overcome the EMI, a proposed three-dimensional (3-D) low-pass filter (LPF) structure is combined with the SRNM wire for noise reduction. To implement the 3-D LPF structure, an industrial passive electronic device (zippered cable shielding) is adopted in this paper. This approach not only achieves a remarkable noise amplitude reduction but also minimizes the radiated emissions from the FMCRD cables, yielding an improved and stabilized nuclear reactor. In addition, a real-time analytical method is utilized to capture events while the FMCRDs are active, and the captured waveforms are transferred to the frequency domain by using a fast Fourier transform to analyze the experiment data, lending more insight into the actual situation. [ABSTRACT FROM PUBLISHER]