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Rising CO₂levels are leading to an increase in atmospheric greenhouse gas effect. Hydroxide salts have previously been shown to be promising reagents for capturing CO₂. Utilizing a 5 %Ru/Al₂O₃catalyst, the carbonates obtained through CO₂capture can then be hydrogenated to methane. This conversion occurs at relatively mild temperatures from 200 °C to 250 °C under 40 to 70 bar H₂with yields of up to 100 %. Natural sources of calcium carbonate, like eggshells and seashells, can also be partially converted to methane. The direct air CO₂capture and conversion of CO₂to methane was achieved as well in quantitative yields.

 

Cellulose is one of the main components of plant matter, which makes it a viable target for biomass conversion to fuels. The direct conversion of cellulose to methane utilizing nickel‐based catalysts often has challenges associated with it. Carbon agglomeration creating nickel‐carbon nanoparticles deactivating catalytic hydrogenation of cellulose has been well reported. Utilizing rare‐earth metals as promoters increases the conversion of cellulose to methane, albeit with deactivation of the catalyst in the form of nickel‐rare‐earth‐carbon nanoparticles. Adding an additional zinc metal promoter eliminates the carbon agglomeration and allows for increased methane yields. Herein, we report an 81 % methane yield from cellulose in 48 hours utilizing a Ni/Zn/Y/Al₂O₃catalyst at 225 °C and under 50 bar H₂pressure.

 

A series of bimetallic carbene-metal-amide (cMa) complexes have been prepared with bridging biscarbene ligands to serve as a model for the design of luminescent materials with large oscillator strengths and small energy differences between the singlet and triplet states (dE ST). The complexes have a general structure (R2N)Au(:carbene—carbene:)Au(NR2). The bimetallic complexes show solvation-dependent absorption and emission that is analyzed in detail. It is found that the molar absorptivity of the bimetallic complexes is correlated with the energy barrier to rotation of the metal-ligand bond. The bimetallic cMa complexes also exhibit short emission lifetimes (t = 200-300 ns) with high photoluminescence efficiencies (PL >95%). The radiative rates of bimetallic cMa complexes are 3 to 4 times faster than that of the corresponding monometallic complexes. Analysis of temperature-dependent luminescence data indicates that the lifetime for the singlet state (τ_(S_1 )) of bimetallic cMa complexes are near 12 ns with a dE ST of 40 50 meV. The presented compounds provide a general design for cMa complexes to achieve small values for dE ST while retaining high radiative rates. Solution processed OLEDs made using two of the complexes as luminescent dopants show high efficiency and low roll-off at high luminance. 

We introduce an electrochemical approach to recycle carbon fiber (CF) fabrics from amine-epoxy carbon fiber-reinforced polymers (CFRPs). Our novel method utilizes a Kolbe-like mechanism to generate methyl radicals from CH 3 COOH to cleave C–N bonds within epoxy matrices via hydrogen atom abstraction. Recovered CFs are then remanufactured into CFRPs without resizing. 

This study presents the synthesis and characterization of two spirobifluorenyl derivatives substituted with either triphenylmethyl (SB-C) or triphenylsilyl (SB-Si) moieties for use as host materials in phosphorescent organic light-emitting diodes (PHOLED). Both molecules have similar high triplet energies and large energy gaps. Blue Ir(tpz)3 and green Ir(ppy)3 phosphorescent devices were fabricated using these materials as hosts. Surprisingly, SB-Si demonstrated superior charge-transporting ability compared to SB-C, despite having similar energies for their valence orbitals. In particular, SB-Si proved to be a highly effective host for both blue and green devices, resulting in maximum efficiencies of 12.6% for the Ir(tpz)3 device and 9.6% for the Ir(ppy)3 device. These results highlight the benefits of appending the triphenylsilyl moiety onto host materials and underscore the importance of considering the morphology of hosts in the design of efficient PHOLEDs.

 

Generating a sustainable fuel from sunlight plays an important role in meeting the energy demands of the modern age. Herein we report two-coordinate carbene-metal-amide (cMa, M = Cu(I) and Au(I)) complexes can be used as sensitizers to promote the light driven reduction of water to hydrogen. The cMa complexes studied here absorb visible photons (vis > 103 M-1cm-1), maintain long excited state lifetimes (~ 0.2-1 s) and perform stable photo-induced charge transfer to a target substrate with high photoreducing potential (E+/* up to 2.33 V vs. Fc+/0 based on a Rehm-Weller analysis). We pair these coinage metal complexes with a cobalt-glyoxime electrocatalyst to photocatalytically generate hydrogen and compare the performance of the copper- and gold-based cMa complexes. We also find that these two-coordinate complexes presented can perform photo-driven hydrogen production from water without the addition of the cobalt-glyoxime electrocatalyst. In this “catalyst free” system the cMa sensitizer partially decomposes to give metal nanoparticles that catalyze water reduction. This work identifies two-coordinate coinage metal complexes as promising abundant metal, solar fuels photosensitizers that offer exceptional tunability and photoredox properties. 

We report two bifunctional (pyridyl)carbene-iridium( i ) complexes that catalyze ketone and aldehyde hydrogenation at ambient pressure. Aryl, heteroaryl, and alkyl groups are demonstrated, and mechanistic studies reveal an unusual polarization effect in which the rate is dependant of proton, rather than hydride, transfer. This method introduces a convenient, waste-free alternative to traditional borohydride and aluminum hydride reagents. 

CO2 captured species with aqueous metal phosphates are converted to methane in an integrated hydrogenation process over a heterogeneous catalyst. 

A new ligand comprising directly-connected disulfide-based anchors provides access to air-stable metal bis(terpyridine) complexes for the functionalization of metal surfaces.

 

Reaction of poly(vinyl chloride) (PVC) with 5 equiv. of triethyl silane in THF, in the presence of in situ generated (xantphos)RhCl catalyst, results in partial reduction of PVC via hydrodechlorination to yield poly(vinyl chloride- co -ethylene). Increasing catalyst loading or using N , N -dimethylacetamide (DMA) as a solvent both diminished selectivity for hydrodechlorination, promoting competitive dehydrochlorination reactions. Reaction of PVC with 2 equiv. of sodium formate in THF in the presence of (xantphos)RhCl affords excellent selectivity for hydrodechlorination along with complete PVC dechlorination, yielding polyethylene-like polymers. Higher catalyst loadings were necessary to activate PVC towards reduction in this case. In contrast, reaction of PVC with 1 equiv. of NaH in DMA, in the presence of (xantphos)RhCl, exhibited good selectivity for dehydrochlorination, as well as much higher reaction rates. These results combined shed light on the interplay between critical reaction parameters that control PVC's mode of reactivity.