Latest ArticlesIn power storage technology, ion exchange is widely used to modify the electronic structures of electrode materials to stimulate their electrochemical properties. Here, we proposed a multistep ion exchange (cation exchange and anion exchange) strategy to synthesize amorphous Ni-Co-S and β-Co(OH)2 hybrid nanomaterials with a hollow polyhedron structures. The synergistic effects of different components and the remarkable superiorities of hollow structure endow Ni-Co-S/Co(OH)2 electrode with outstanding electrochemical performance, including ultra-high specific capacity (1440.0 C/g at 1 A/g), superior capacitance retention rate (79.1% retention at 20 A/g) and long operating lifespan (81.4% retention after 5000 cycles). Moreover, the corresponding hybrid supercapacitor enjoys a high energy density of 58.4 Wh/kg at the power density of 0.8 kW/kg, and a decent cyclability that the capacitances are maintained at 80.8% compared with the initial capacitance. This research presents a high-performance electrode material and provides a promising route for the construction of electrode materials for supercapacitors with both structural and component advantages.
Bi draws increasing attention as anode materials for lithium-ion batteries and sodium-ion batteries due to its unique layered crystal structure, which is in favor of achieving fast ionic diffusion kinetics during cycling. However, the dramatic volume expansion upon lithiation/sodiation and an insufficient theoretical capacity of Bi greatly hinder its practical application. Herein, we report the Fe2O3 nanoparticle-pinning Bi-encapsulated carbon fiber composites through the electrospinning technique. The introduction of Fe2O3 nanoparticles can prevent the growth and aggregation of Bi nanoparticles during synthetic and cycling processes, respectively. Fe2O3 with high specific capacity also contributes to the specific capacity of the composites. Consequently, the as-prepared Bi-Fe2O3/carbon fiber composite exhibits outstanding long-term stability, which delivers reversible capacities 504 and 175 mAh/g after 1000 cycles at 1 A/g for lithium-ion and sodium-ion batteries, respectively.
Ion-in-conjugation (IIC) materials are emerging as an important class of organic electronic materials with wide applications in energy storage, resistive memories and gas sensors. Many IIC materials were designed and investigated, however the role of conjugation in IIC materials' performance is yet investigated. Here we designed two molecules obtained by condensation of 4-butylaniline and oxocarbon acid. Squaric acid derivatives squaraine named SA-Bu and a croconamide named CA-Bu which only differ in their oxocarbon cores. While employing SA-Bu and CA-Bu as resistive memory and gas sensory materials, SA-Bu has attained promising performance in ternary memory and detection of NO2 as low as 10 parts-per-billion whereas CA-Bu show mainly binary memory behavior and negligible NO2 response. Theoretical calculations reveal that conjugation of CA-Bu was distorted by the increased steric hindrance, frustrating the charge transport and suppressing the conductivity. Our work demonstrates that the conjugation plays a crucial role in ion-in-materials promoting ternary RRAM devices and high-performance gas sensors manufacture.
CO2 capture is considered as one of the most ideal strategies for solving the environmental issues and against global warming. Recently, experimental evidence has suggested that aluminum double bond (dialumene) species can capture CO2 and further convert it into value-added products. However, the catalytic application of these species is still in its infancy. Both the dynamics mechanism of CO2 fixation and the detailed structures of catalytic intermediates are not well understood. In this work, we investigate the structure dependent resonance Raman (RR) signals for different reaction intermediates. Ab-initio simulations of spontaneous resonance Raman (spRR) and time-domain stimulated resonance Raman (stRR) give spectral signatures correlated to the existence of different intermediates during the CO2-dialumene binding process. The unique Raman vibronic features contain rich structural information with high temporal resolution, enabling to monitor the transient catalytic intermediates under reaction conditions. Our work shows that RR can be used to monitor intermediates during the dialumene based CO2 capture reaction. The spectral features not only provide insight into the structural information of intermediate species, but also allow a deeper understanding of the dynamical details of this kind of catalytic process.
Fabrication of well-designed heterojunctions is an extraordinarily attractive pathway for boosting the photocatalytic activity toward CO2 photoreduction. Herein, a novel kind of nanosheet-based intercalation hybrid coupled with CdSe quantum dots (QDs) was successfully fabricated by a facile solvothermal method and served as photocatalyst for full-spectrum-light-driven CO2 reduction. Ultra-small CdSe QDs were rationally in-situ introduced and coupled with lamellar ZnSe-intercalation hybrid nanosheet, resulting in the formation of CdSe QDs/ZnSe hybrid heterojunction. Significantly, the concentration of Cd2+ could change directly the crystallinity and micromorphology of ZnSe intercalation hybrid, which in turn would impact on the photocatalysis activity. The optimized CdSe QDs/ZnSe hybrid-5 composite demonstrated a considerable CO yield rate of the 25.6 μmol g-1 h-1 without any additional cocatalysts or sacrificial agents assisting, making it one of the best reported performance toward CO2 photoreduction under full-spectrum light. The elevated CO2 photoreduction activity could be attributed to the special surface heterojunction, leading to improving the ability of light absorption and promoting the separation/transfer of photogenerated carriers. This present study developed a new strategy for designing inorganic-organic heterojunctions with enhanced photocatalyst for CO2 photoreduction and provided an available way to simultaneously mitigate the greenhouse effect and alleviate energy shortage pressure.
DNA methyltransferase (DNMT) and histone deacetylase (HDAC) are well recognized epigenetic targets for discovery of antitumor agents. In this study, we designed and synthesized a series of nucleoside base hydroxamic acid derivatives as DNMT and HDAC dual inhibitors. MTT assays and enzymatic inhibitory activity tests indicated that compound 204 exhibited potent DNMT1 and HDAC1/6 inhibitory potency simultaneously in enzymatic levels and at cellular levels, inducing hypomethylation of p16 and hyperacetylation of histones H3K9 and H4K8. Besides, 204 remarkably inhibited proliferation against cancer cells U937 by prompting G0/G1 cell cycle arrest. Molecular docking models explained the functional mechanism of 204 inhibiting DNMT1 and HDAC. Preliminary studies on metabolic profiles revealed that 204 showed desirable stability in liver microsomes. Our study suggested that 204 inhibiting DNMT and HDAC concurrently can be a potential lead compound for epigenetic cancer therapy.
Electrochemical water splitting is a facile and effective route to generate pure hydrogen and oxygen. However, the sluggish kinetics of hydrogen evolution reaction (HER) and especially oxygen evolution reaction (OER) hinder the water splitting efficiency. Meanwhile, the high-cost of noble-metal catalysts limit their actual application. It is thus highly urgent to exploit an economical and earth-abundant bifunctional HER and OER electrocatalyst to simplify procedure and reduce cost. Herein, we synthesize the three-dimensionally ordered macro-/mesoporous (3DOM/m) NixCo100-x alloys with distinctive structure and large surface area via a dual-templating technique. Among them, the 3DOM/m Ni61Co39 shows the lowest overpotentials of 121 mV and 241 mV at 10 mA/cm2 for HER and OER, respectively. Furthermore, when employed for water splitting, the Ni61Co39 only requires 1.60 V to approach 10 mA/cm2 and presents excellent stability. These encouraging performances of the Ni61Co39 render it a promising bifunctional catalyst for overall water splitting.
Different from traditional metal-support heterogenous catalysts, inverse heterogeneous catalysts, in which the surface of metal is decorated by metal oxide, have recently attracted increasing interests owing to the unique interfacial effect and electronic structure. However, a deep insight into the effect of metal-oxide interaction on the catalytic performance still remains a great challenge. In our work, an inverse hematite/palladium (Fe2O3/Pd) hybrid nanostructure, i.e., the active Fe2O3 ultrathin oxide layers partially covering on the surface of Pd nanoparticles (NPs), exhibited superior electrocatalytic performance towards methanol oxidation reaction (MOR) as compared to the bare Pd NPs based on density functional theory calculation. The charge could transfer from Pd to Fe2O3 driven by the built-in potential at the interface of Pd and Fe2O3, which favors the downshift of d band center of Pd. With the assistance of interfacial hydroxyl OH*, the cleavage of OH and CH in CH3OH could take place much easily with lower barrier energy on Fe2O3/Pd than that on pure Pd via two electrons transferring reaction pathways. Our results highlight that the synergy of Pd and Fe2O3 at the interface could facilitate the electrochemical transformation of methanol into formaldehyde assisted with interfacial hydroxyl OH*.
Morphology and dispersity are key factors for activating peroxymonosulfate (PMS). In this study, we designed a recyclable open-type NiCo2O4 hollow microsphere via a simple hydrothermal method with the assistance of an NH3 vesicle. The physical structure and chemical properties were characterized using techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), N2 adsorption and X-ray photoelectron spectroscopy (XPS). The test results confirm that the inner and outer surfaces of open-type NiCo2O4 hollow-sphere can be efficiently utilized because of the hole on the surface of the catalyst, which can minimize the diffusion resistance of the reactants and products. Under optimized conditions, the total organic carbon (TOC) removal efficiency of rhodamine B (RhB) can reach up to 80% in 40 min, which is almost 50% shorter than the reported values. The reactive radicals were identified and the proposed reaction mechanism was well described. Moreover, the disturbances of HCO3−, NO3−, Cl− and H2PO4− were further investigated. As a result, HCO3− and NO3− suppressed the reaction while Cl− and H2PO4− had a double effect on reaction.
Microbial fuel cells (MFCs) have various potential applications. However, anode is a main bottleneck that limits electricity production performance of MFCs. Herein, we developed a novel anode based on a stainless steel cloth (SC) modified with carbon nanoparticles of Chinese ink (CI) using polypyrrole (PPy) as a building block (PPy/CI/SC). After modification, PPy/CI/SC showed a 30% shorten in start-up time (36.4 ± 3.3 h vs. 52.3 ± 1.8 h), 33% increase in the maximum current (12.4 ± 1.4 mA vs. 9.3 ± 0.95 mA), and 2.3 times higher in the maximum power density of MFC (61.9 mW/m2 vs. 27.3 mW/m2), compared to Ppy/SC. Experimental results revealed that carbon nanoparticles were able to cover SC uniformly, owing to excellent dispersibility of carbon nanoparticles in CI. The attachment of carbon nanoparticles formed a fluffy layer on SC increased the electrochemically-active surface area by 1.9 times to 44.5 cm2. This enhanced electron transfer between the electrode and bacteria. Further, embedding carbon nanoparticles into the PPy layer significantly improved biocompatibility as well as changed functional group contents, which were beneficial to bacteria adhesion on electrodes. Taking advantage of high mechanical strength and good conductivity, a large-size PPy/CI/SC was successfully prepared (50 × 60 cm2) demonstrating a promising potential in practical applications. This simple fabrication strategy offers a new idea of developing low cost and scalable electrode materials for high-performance energy harvesting in MFCs.
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