Developing highly efficient electrocatalysts based on cheap and earth-abundant metals for CO
reduction is of great importance. Here we demonstrate that the electrocatalytic activity of ...manganese-based heterogeneous catalyst can be significantly improved through halogen and nitrogen dual-coordination to modulate the electronic structure of manganese atom. Such an electrocatalyst for CO
reduction exhibits a maximum CO faradaic efficiency of 97% and high current density of ~10 mA cm
at a low overpotential of 0.49 V. Moreover, the turnover frequency can reach 38347 h
at overpotential of 0.49 V, which is the highest among the reported heterogeneous electrocatalysts for CO
reduction. In situ X-ray absorption experiment and density-functional theory calculation reveal the modified electronic structure of the active manganese site, on which the free energy barrier for intermediate formation is greatly reduced, thus resulting in a great improvement of CO
reduction performance.
Abstract
The production of 2D metal-organic frameworks (MOFs) with highly exposed active surfaces is of great importance for catalysis. Here we demonstrate the formation of MOF nanosheets by ...utilizing CO
2
as a capping agent to control the oriented growth of MOF. This strategy has many advantages over the conventional methods. For example, it is template-free and proceeds at mild temperature (35 °C), CO
2
can be easily removed by depressurization, and the properties of the MOF nanosheets can be well adjusted by changing CO
2
pressure. Such a simple, rapid, efficient and adjustable route produces MOF nanosheets with ultrathin thickness (∼10 nm), small lateral size (∼100 nm) and abundant unsaturated coordination metal sites on surfaces. Owing to these unique features, the as-synthesized MOF nanosheets exhibit superior activity for catalyzing the oxidation reactions of alcohols.
The electrochemical synthesis of chemicals from carbon dioxide, which is an easily available and renewable carbon resource, is of great importance. However, to achieve high product selectivity for ...desirable C2 products like ethylene is a big challenge. Here we design Cu nanosheets with nanoscaled defects (2–14 nm) for the electrochemical production of ethylene from carbon dioxide. A high ethylene Faradaic efficiency of 83.2% is achieved. It is proved that the nanoscaled defects can enrich the reaction intermediates and hydroxyl ions on the electrocatalyst, thus promoting C–C coupling for ethylene formation.
Electrochemical conversion of CO2 to valuable fuels is appealing for CO2 fixation and energy storage. The Cu‐based catalysts feature unique superiorities, but achieving high ethylene selectivity is ...still restricted. In this study, we propose the anchoring of an ionic liquid (IL) on a Cu electrocatalyst for improving the electrochemical CO2 reduction to ethylene. In a water‐based electrolyte and a commonly used H‐type cell, a high ethylene Faradaic efficiency of 77.3 % was achieved at −1.49 V (vs. RHE). Experimental and theoretical studies reveal that an IL can modify the electronic structure of a Cu catalyst through its interaction with Cu, making it more conducive to *CO dimerization for ethylene formation.
The ionic liquid 1‐butyl‐3‐methylimidazolium nitrate (BmimNO3) was anchored into Cu, through which the atomic coordination and electronic properties of Cu can be optimized to facilitate C−C coupling. This electrocatalyst can reduce CO2 to C2H4 with high selectivity. The Faradaic efficiency of C2H4 reaches 77.3 % at −1.49 V (vs. RHE) in KHCO3 aqueous solution using a H‐type cell, much higher than that over pure Cu catalyst (31.2 %).
The electroreduction of CO
2
to valuable chemicals and fuels offers an effective mean for energy storage. Although CO
2
has been efficiently converted into C
1
products (e.g., carbon monoxide, formic ...acid, methane and methanol), its convention into high value-added multicarbon hydrocarbons with high selectivity and activity still remains challenging. Here we demonstrate the formation of multi-shelled CuO microboxes for the efficient and selective electrocatalytic CO
2
reduction to C
2
H
4
. Such a structure favors the accessibility of catalytically active sites, improves adsorption of reaction intermediate (CO), inhibits the diffusion of produced OH
−
and promotes C—C coupling reaction. Owing to these unique advantages, the multi-shelled CuO microboxes can effectively convert CO
2
into C
2
H
4
with a maximum faradaic efficiency of 51.3% in 0.1 M K
2
SO
4
. This work provides an effective way to improve CO
2
reduction efficiency via constructing micro- and nanostructures of electrocatalysts.
To improve the interlaminar properties of carbon fiber reinforced polymer composites (CFRPs), a hybrid fiber mat (i-MBP-PCF) was prepared by in situ deposition of a multiwalled carbon nanotube ...buckypaper (i-MBP) on the surface of functionalized CF fabric (PCF). The effect of the hybrid fiber mat on the interlaminar and electrical properties was systematically investigated. The results showed that the i-MBP-PCF hybrid fiber mat showed excellent interlaminar and electrical property enhancement functions. The interlaminar shear strength (ILSS), Mode-II interlaminar fracture toughness (GIIC), and electrical conductivity in the out-of-plane direction of i-MBP-PCF/EP increased 68.6%, 44.4%, and 6080%, respectively, compared to those of the CF/EP composite.
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•A novel hybrid fiber mat was prepared by in situ depositings of a carbon nanotubes buckypaper on a modified carbon fabric.•The hybrid fiber mat showed excellent interlaminar shear and electrical properties enhancement effects.•Composites’ interlaminar shear strength (59MPa) and mode-II toughness (650J/m2) increased by 68.6% and 44.4% respectively.•The electrical conductivity in the out-of-plane and the in-plane direction increased by 6080% and 7 folds respectively.•The hybrid fiber mat has huge application potential in aerospace, conducting elements, and structural materials.
Hybrid nanoparticles, fullerene (C60) and polyaniline (PANI), were incorporated into the polydivinylbenzene (PDVB), and their decoupling effect of electrical and thermal conductivity was ...investigated. The hybrid particles were fabricated through simple one-step process in the solution of divinylbenzene (DVB) monomer. The morphology and structure were characterized by TEM, SEM and FTIR. After the incorporation of C60/PANI hybrids into DVB monomer, the electrical conductivity was improved significantly while the thermal conductivity was reduced simultaneously, resulting in effectively decoupling thermal/electrical conductivity. The AC electrical conductivity increased from 9 × 10−10 S/m to 63.7 S/m at the frequency of 1 Hz, more than 10 orders of magnitude. On the contrary, the thermal conductivity was reduced to extremely low of only 0.164 W/m·K from 0.579 W/m·K. Dissipative particle dynamics (DPD) simulations was also conducted to gain further understanding about the decoupling effect and mechanisms related to dispersibility of C60 in polymer system. The DPD results exhibited better agreement with the experiment results of electrical and thermal conductivity. These results indicate that DPD can be a versatile method for designing functional polymer composites. Simultaneously, the decoupling of electrical and thermal conductivity of polymer bulk composites opens diverse opportunities for new materials and systems.
To construct the heterojunctions of TiO
2
with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance. Here we propose ...the construction of TiO
2
/covalent organic framework (COF) heterojunction with tight connection by a supercritical CO
2
(SC CO
2
) method, which helps bridging the transformation paths for photo-induced charge between TiO
2
and COF. The produced TiO
2
/COF heterojunction performs a H
2
evolution of 3,962 µmol·g
−1
·h
−1
under visible-light irradiation, which is ∼ 25 times higher than that of pure TiO
2
and 4.5 folds higher than that of TiO
2
/COF synthesized by the conventional solvothermal method. This study opens up new possibilities for constructing heterojunctions for solar energy utilization.
Overall goal of this research is to study the conductivity enhancement effect and its mechanism for different types of carbon-based nano-fillers/conduct polymer hybrids in carbon fiber reinforced ...polymer (CFRP). Multi-walled carbon nanotubes (MWCNT)/polyaniline (PANI) and graphene oxide (GO)/PANI hybrids were separately dispersed into divinylbenzene (DVB) to make the CFRP composites. The alternating current (AC) electrical conductivity results show that both, the binary MWCNT/PANI and GO/PANI hybrids have significant enhancement on AC conductivity, while MWCNT/PANI gives better improvement over GO/PANI hybrids. The mechanism for the conductivity enhancement was studied by SEM, XRD, UV–Vis and nanoindentor. Circuit models were proposed. The maximum AC conductivity of CFRP made of MWCNT/PANI was measured to be 22.4 S/m, which has been found to be enhanced by more than 3 orders of magnitude compared to CF/DVB. Thus, CF/MWCNT-PANI composites can be considered to be promising candidates for multifunctional material where high conductivity is demanded.
Utilizing synergetic effect of different ingredients is an important strategy to design new multi-functional composites. In this work, high-strength graphene oxide and conductive polyaniline were ...selected to dope into divinylbenzene to fabricate a new type carbon fiber reinforced polymer laminates, where a cooperative improvement of through-thickness electrical conductivity and interlaminar shear strength was observed. With addition of 15wt% of PANI-GO at the optimized weight ratio of 60:1 in the CF/DVB-PANI-GO, 150% enhancement of the electrical conductivity compared to the CF/DVB-PANI, and 76% enhancement of the ILSS compared to the CF/DVB-GO were realized. Our laminates reach 66% in ILSS of that for the conventional CFRP made of epoxy, but the former features about 103 times higher AC conductivity. The mechanism for such a synergic enhancement for both electrical and mechanical performance was investigated by rheology measurement and scanning electron microscopy, where uniform 3-D network formed by PANI/GO has been clearly observed.
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