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Ru nanoparticle inserted porous carbon nanofibers were facilely fabricated and used as highly efficient levulinic acid hydrogenation catalysts.

Biomass resources are growing in concern in electromagnetic interference (EMI) shielding due to the advantages of low-cost, sustainability, and unique structural feature. From the perspective of “waste to wealth” and sustainable development, novel straw-derived hollow porous carbon-tube arrays (SCAs) have been fabricated through direct carbonization of wheat straw followed by orderly assembly for the first time. The resultant SCAs with increased SC diameter of ∼1.7–3.3 mm showed not only low apparent density of ∼72–33 mg/cm3 due to the presence of arrayed hollow macrostructure, but also high EMI SE of ∼57.7–44.0 dB coming from both the strong EM reflection and conductive dissipation, as well as hierarchical internal multiple reflections. After the further construction of ultralight graphene aerogel (GA) in their hollow interior, the GA/SCAs with slightly increased density of only ∼78–39 mg/cm3 exhibited obvious SE enhancement of ∼66.1–70.6 dB compared to those of neat SCAs. In addition, the performance comparison between our SCAs and other previously reported carbon foams also revealed the more advanced configuration of hollow porous carbon-tube array for lightweight and high-performance EMI shielding application.

Natural cotton was selected as a cheap and renewable carbon source to fabricate novel carbon networks with porous three-dimensional conductive frameworks composed of numerous unique hollow carbon fibers by pyrolysis, and outstanding electromagnetic interference (EMI) shielding effectiveness (SE) of ∼26.9–46.9 dB was observed for the samples (∼0.3 mm in thickness) with density of ∼0.14–0.06 g/cm3. Moreover, the combination of cotton-derived carbon networks with graphene through the construction of a sandwich configuration, where graphene sheets were dispersed inhomogeneously on both sides of carbon networks, was further developed and the resultant carbon composite networks with ultrathin skin layers of graphene film in thickness of only ∼2 μm possessed higher EMI SE of ∼48.5–87.0 dB than that (∼33.7–55.6 dB) of pure carbon networks in thickness of ∼0.3–0.7 mm, possibly due to the enhanced EM reflection and absorption of EM waves penetrating the material. The SE increment of ∼26–41% was also observed in the sandwiched samples in comparison with the counterparts with homogeneous graphene dispersion, demonstrating a very promising configuration for the significant SE enhancement.

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Nickel/nanoporous carbon (Ni/NPC) composites are facilely prepared by direct pyrolysis of nonporous heterobimetallic zinc-nickel-terephthalate frameworks (Zn 1Àx Ni x MOF, x % 0-1, MOF = metal-organic framework) at 1223 K in situ. Tailoring the Ni/Zn ratio creates densely populated and small Ni nanocrystals (Ni NCs) while maintaining sufficient porosity and surface area in the final product, which exhibits the largest activity factor (9.2 s À1 g À1 ) and excellent stability toward 4-nitrophenol reduction.Catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is an important and environmentally benign process, as it converts the most prevalent organic pollutant in waste waters generated from agricultural and industrial sources, 4-NP, into an industrially relative amino compound for aniline and paracetamol production. [1] At present, the catalytic materials of choice are mainly precious or doped precious metals (such as Au, Pd, Ag, PtNi, AuCu, PdCu, etc.). [2] The high cost and limited reserves of precious metals, however, create a major barrier for their large-scale application in pollutant degradation. Intensive efforts have been dedicated to the search of low-costing alternatives. The discovery of 4-NP reduction activity on nickel catalysts stimulated extensive investigation of various Ni-containing nanostructures, such as NiCo 2 , NiCu alloy, Ni-brush, Ni@silica, Ni/SiO 2 -Al 2 O 3 , and Ni@MWCNT (MWCNT = multiwalled carbon nanotube as nonprecious catalysts. [3] Significant progress towards 4-NP reduction has been recently achieved over nickel-based mesoporous carbon materials, as chemically inert mesostructured carbon materials provide good diffusion owing to their large pore sizes and volumes. [4] Unfortunately, besides the tedious synthetic procedure required for such catalysts, another challenge is that their turnover frequency is low relative to that of precious metals. To compensate this low activity, an excess amount of the catalyst is often used, but this results in a high production cost. It is therefore desirable to produce large amounts of nickel catalytic sites that are evenly and densely distributed over a mesoporous carbon matrix in a convenient manner.Currently, metal-organic frameworks (MOFs) as a novel class of nanoporous crystalline materials built from transition-metal clusters as nodes and organic ligands as struts have been demonstrated as promising precursors that yield highly nanoporous carbon materials showing excellent properties in gas adsorption, electrochemical capacitance, sensing, and catalysis. [5] One of the advantages of using MOFs for the preparation of nanoporous carbon materials is that carbon-metal/metal oxide hybrids can be simply achieved after carbonization. Frequently, porous single-metal MOFs function as a secondary carbon precursor and a primary carbon precursor, and typically furfuryl alcohol (FA) is impregnated and subsequently polymerized inside the micropores of the MOFs. Applying such a method, microporous carbon fibers with embedded g-alumina nano...