Latest ArticlesMetal skeletons, such as Nickel Foam (NF) has attracted worldwide interests as stable host for lithium metal anode because of its high stability, large specific surface area and high conductivity. However, most metal skeletons have lithophobic surface and uneven current distribution that result in sporadic lithium nucleation and uncontrolled dendrites growth. Herein, we describe a sequential immersing strategy to generate interwoven Nickel(Ⅱ)-dimethylglyoxime (Ni-DMG) nanowires at NF to obtain composite skeleton (NDNF), which can be used as an stable host for Li metal storage. The Ni-DMG has proved effective to realize uniform lithium nucleation and dendrite-free lithium deposition. Combing with the three dimensional (3D) hierarchical porous structure, the composite host shows a significantly improved coulombic efficiency (CE) than pristine commercial nickel foam. Moreover, the corresponding Li||Li symmetrical cells can run more than 700 h with low voltage hysteresis 22 mV at 1.0 mA/cm2, and Li@NDNF||LiFePO4 full-cell exhibits a high capacity retention of 82.03% at 1.0 C during 630 cycles. These results proved the effectiveness of metal-organic complexes in governing Li metal growth and can be employed as a new strategy for dendrite-free Li metal anode and safe Li metal batteries (LMBs).
Designing highly efficient non-precious based electrocatalysts for oxygen reduction reaction (ORR) is of significance for the rapid development of metal-air batteries. Herein, a hydrothermal-pyrolysis method is employed to fabricate Fe, N co-doped porous carbon materials as effective ORR electrocatalyst through adopting graphitic carbon nitride (g-C3N4) as both the self-sacrificial templates and N sources. The g-C3N4 provides a high concentration of unsaturated pyridine-type N to coordinate with iron to form Fe-N active sites. Through adjusting the Fe doping amounts, it is proved that appropriate Fe doping content is conducive to the construction of abundant defects and active sites of Fe-N. The as-prepared catalyst exhibits superior electrocatalytic ORR performance in alkaline media with half-wave potential (E1/2 = 0.82 V) and onset potential (Eonset = 0.95 V), equivalent to the commercial Pt/C catalyst. Moreover, there is almost no activity loss after 10 k continuous cyclic voltammetry cycles and methanol tolerance, indicating the excellent durability and superior methanol tolerance. Remarkably, when assembled as the cathode in a Zn-air battery, the device displays a power density of 99 mW/cm2, an open-circuit potential of 1.48 V and long-term discharge-charge cycling stability, indicating the promising potential to substitute the Pt catalyst for practical application.
Conventional gels manifest monotonous swelling or shrinking performance upon immersing in solvents until reaching an equilibrium state. Recently, we discovered that the "hydrophobic hydrogels" prepared from hydrophobic polymer networks demonstrated dynamic swelling performance without equilibrium states. Upon water immersion, the gels expanded tremendously at the first stage until reaching a swelling peak; subsequently, the gels shrunk at an extremely slow rate. While this phenomenon endows the material with an unusual feature, more efforts are highly demanding for the full understanding of this performance. Herein, we systematically investigate the hydrophobic hydrogels' swelling kinetics by screening the organic solvent dependence, polymer effect, and temperature impact. It is revealed that the chemical structure of gels greatly influences the swelling kinetics. The higher the networks' hydrophobicity, the slower the swelling kinetics. Meanwhile, organic solvents demonstrate a limited effect on the dynamic swelling performance. Moreover, higher temperature significantly accelerates the whole volume change process. Based on the swelling performance, we further develop hydrogel-based soft devices with time-programmable two-dimensional and three-dimensional shape-shifting performances.
The synthesis of high-value multi-carbon products through the electrochemical reduction of carbon monoxide (COER) is one of the promising avenues for carbon utilization and energy storage, in which searching for efficient electrocatalysts that exhibit moderate CO intermediate binding strength and low kinetic barrier for C-C coupling is a key issue. Herein, by means of comprehensive density functional theory (DFT) computations, we theoretically designed three synergistic coupling catalysts by co-doping transition metal (TM = Fe, Co and Ni) and boron (B) into the two-dimensional black phosphorene (BP), namely TM-B@BP for COER to C2 products. DFT computations and ab initio molecular dynamics simulations reveal the good stability and high feasibility of these proposed TM-B@BP catalysts for practical applications and future experimental synthesis. More interestingly, high-value ethylene (C2H4), ethane (C2H6) and ethanol (C2H5OH) products can be obtained on these three designed electrocatalysts with ultra-small limiting potentials (−0.20~−0.41 V) and low kinetic energy barriers of C-C coupling (0.52~0.91 eV). Meanwhile, the competitive one-carbon (C1) products and hydrogen evolution reaction can also be effectively suppressed. The promising activity and selectivity of these three designed electrocatalysts render them ideal candidates for CO electroreduction, thus providing a cost-effective opportunity to achieve a sustainable production of high value C2 chemicals and fuels.
Nitrogen reduction reactions (NRR) under room conditions remain the challenge for N2 activation on metal-based catalysis materials. Herein, the M-doped CeO2(111) (M = Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) with oxygen vacancies, are systematically investigated by spin-polarized DFT + U calculations. We discuss briefly the situation of OVs on pure and reduced cerium, and we found that (1) doping TMs can promote the formation of oxygen defects, apart from Ti and V-dopant, (2) the O atoms are easier to escape connecting to M atoms than the ones of adjacent atoms connecting to the Ce(III), the value of OVs formation energies decrease as the TMs radius decrease. Also, our computational results show that Cr-doped, Mn-doped, Fe-doped, and Co-doped CeO2(111) adsorbs N2 strongly than the stoichiometric surface and other M-doped CeO2 surfaces with adsorption energies of −0.82, −1.02, −0.83 and −1.05 eV. Through COHP analysis, it is found that the predicted active sites have good catalytic performance.
Bio-based epoxy thermoset prepared from renewable biomass raw materials can alleviate fossil energy crisis and reduce environmental pollution, which satisfies the needs of sustainable social development. In this study, a bio-based epoxy thermoset precursor (MGOL-EP) was synthesized from a naturally occurring magnolol through a facile and efficient one-step process. And the fully bio-based epoxy thermoset (MGOL-EP-SC) was obtained by self-curing without adding any other hardener. MGOL-EP-SC revealed an extremely high glass-transition temperature (Tg) of 265 ℃ and char yield of 53.2% (in N2), which were at the highest level among the fully bio-based epoxy thermosets reported so far. In addition, when the MGOL-EP was cured with 4, 4′-methylenedianiline (DDM), Tg of the MGOL-EP/DDM was decreased by 61 ℃ and the other comprehensive performance had also been decreased, which was due to a reduction in biphenyl structure content and cross-linking density by adding the external curing agents. Moreover, the MGOL-EP-SC presented certain killing rate (48.4%) to Staphylococcus aureus. These findings provide a new design strategy for engineering high-performance and functional epoxy thermoset with high biomass content.
Chloride ion batteries (CIB) are considered to be one of the most promising energy storage devices. As cathode materials for CIBs, metal chlorides have many advantages, such as high theoretical energy density, abundant elemental resources and ideal discharge voltage plateau. However, the dissolution and huge volume change of metal chlorides during cycling lead to considerable short lifespan, which limits their potential application for CIBs. Herein, the bismuth chloride nanocrystal is confined in mesocellular carbon foam matrix by a new vacuum impregnation approach. The mesocellular carbon foam with large interconnected pores (15.7 or 23.2 nm) may buffer the large volume variation of bismuth chloride during charge and discharge, giving rise to significantly enhanced electrochemical performance. The as-prepared bismuth chloride@mesocellular carbon foam cathode delivered an initial discharge capacity of 298 mAh/g and a reversible capacity of 91 mAh/g after 60 cycles. In contrast, the pure bismuth chloride cathode almost cannot discharge after 30 cycles. This is the first report that the metal chloride cathode can achieve a prolonged cycling in CIBs.
Conductive hydrogels have attracted considerable attention owing to their potential for use as electronic skin and sensors. However, the loss of the inherent elasticity or conductivity in cold environments severely limits their working conditions. Generally, organic solvents or inorganic salts can be incorporated into hydrogels as cryoprotectants. However, their toxicity and/or corrosive nature as well as the significant water loss during the solvent exchange present serious difficulties. Herein, a liquid-like yet non-toxic polymer-polyethylene glycol (PEG) was attempted as one of the components of solvent for hydrogels. In the premixed PEG-water hybrid solvent, polyacrylamide (PAAm) was in situ polymerized, overcoming the inevitable water loss induced by the high osmotic pressure of the PEG solution and achieving tailored water capacity. Interestingly, the mechanical strength ("soft-to-rigid" transition) and anti-freezing properties of organohydrogels can be simultaneously tuned over a very wide range through adjusting PEG content. This was due to that with increasing PEG in solvent, the PAAm chains transformed from stretching to curling conformation, while PEG bonded with water molecules via hydrogen bonds, weakening the crystallization of water at subzero temperature. Additionally, a highly conductive Ti3C2Tx-MXene was further introduced into the organohydrogels, achieving a uniform distribution triggered by the attractive interaction between the rich functional groups of the nanofillers and the polymer chains. The nanocomposite hydrogels demonstrate high electrical conductivity and strain sensitivity, along with a wide working temperature window. Such a material can be used for monitoring human joint movement even at low temperature and has potential applications in wearable strain sensors.
Considering the significant importance in both ecological and environmental fields, converting nitrogen oxide (NOx, especially NO) into value-added NH3 or harmless N2 lies in the core of research over the past decades. Exploring catalyst for related gas molecular activation and highly efficient reaction systems operated under low temperature or even mild conditions are the key issues. Enormous efforts have been devoted to NO removal by utilizing various driving forces, such as thermal, electrical or solar energy, which shine light on the way to achieve satisfying conversion efficiency. Herein, we will review the state-of-the-art catalysts for NO removal driven by the above-mentioned energies, including a comprehensive introduction and discussion on the pathway and mechanism of each reaction, and the recent achievements of catalysts on each aspect. Particularly, the progress of NO removal by environmentally friendly photocatalysis and electrocatalysis methods will be highlighted. The challenges and opportunities in the future research on the current topic will be discussed as well.
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