Latest ArticlesThe exploration of advanced materials through rational structure/phase design is the key to develop high-performance lithium-ion capacitors (LICs). However, high complexity of material preparation and difficulty in quantity production largely hinder the further development. Herein, Cu5FeS4-x/C (CFS@C) heterojunction with rich sulfur vacancies has successfully achieved from natural bornite, presenting low cost-effective and bulk-production prospect. Density functional theory (DFT) calculations indicate that rich vacancies in bulk phase can decrease band gap of bornite and thus improve its intrinsic electron conductivity, as well as the heterojunction spontaneously evokes a built-in electric field between its interfacial region, largely reducing the migration barrier from 1.27 eV to 0.75 eV. Benefited from these merits, the CFS@C electrodes deliver outperformed lithium storage performance, e.g., high reversible capacity (822.4 mAh/g at 0.1 A/g), excellent cycling stability (up to 820 cycles at 2 A/g and 540 cycles at 5 A/g with respective capacity retention of over or nearly 100%). With CFS@C as anode and porous carbon nanosheets (PCS) as cathode, the assembled CFS@C//PCS LIC full cells exhibit high energy/power density characteristics of 139.2 Wh/kg at 2500 W/kg. This work is expected to offer significant insights into structure modifications/devising toward natural minerals for advanced energy-storage systems.
In recent years, the emerging two−dimensional material−MXenes has attracted widespread attention in the field of photocatalysis due to its high conductivity, suitable Fermi level, tunable elemental composition, and excellent photoelectric properties. The zero−dimensional quantum dots (MQDs) derived from 2D MXenes not only inherit the characteristics of MXenes but also exhibit better performance due to the quantum size effect. Based on the above excellent physical and chemical properties, MQDs are often used as co−catalysts of photocatalysts, and show excellent co−catalytic properties. At the same time, compared with other cocatalysts (precious metals, metal oxides, metal sulfides), it has the advantages of low cost and high conductivity. Therefore, understanding the status of MQDs in the field of photocatalysis is crucial for their further development. In this review, we summarized the synthesis and modification methods of MQDs in recent years, as well as their photocatalytic applications in H2 production, CO2 reduction, N2 fixation, pollutant degradation, and other aspects. In addition, the challenges and prospects faced by MQDs are also proposed, providing theoretical guidance for the further development of MQD−based photocatalysts.
Elevated level of hypochlorous acid (HClO) is closely associated with cancer development. Identifying HClO level in cancer cells would provide important evidence in either early-stage cancer diagnostics or monitoring of its treatment efficiency. In this work, a new pyronine-based fluorescent probe for rapid and sensitive detection of HClO was developed by condensing meso–formyl pyronine (PyCHO) with 2-hydrazinopyridine to form meso–pyridylhydrazone-functionalized pyronine PyHP, PyHP is nonfluorescent due to the excited-state C=N isomerization nonradiative decay, whereas the HClO-triggered formation of meso–triazolopyridyl pyronine PyTP abolishes the C=N isomerization and thus greatly enhances the fluorescence. With the probe, the cancer cells/tumor were distinguished with high-contrast from normal ones by laser confocal fluorescence imaging, and the tumor-to-normal (T/N) ratios obtained exceed the clinically acceptable threshold of 2.0. Moreover, its capability of in vivo imaging tumor was also demonstrated. These results indicate the potential of PyHP as an effective tool in the early clinical diagnosis of cancers.
Lead-halide perovskites exhibit outstanding performance in X-ray detection due to their intrinsic features such as high charge carrier mobility, large atomic number, and long carrier lifetime, but the toxicity of lead is regarded as the major factor hindering their development. Here, we introduce organic molecule (R)-(-)-2-methylpiperazine (R-MPz) into the bismuth-based structure to synthesize lead-free (R)-(H2MPz)BiI5 (R-MBI). The high-quality centimeter-sized single crystals have been obtained, which show a low dark current and superior environmental stability. Particularly, the single-crystal device of R-MBI exhibits a high μτ product up to 1.88 × 10−4 cm2/V and a low trap density of 1.21 × 1010 cm−3. Further, the detector displays excellent detection sensitivity of 263.58 µC Gyair−1 cm−2 and a favorable low detection limit of 4.35 µGyair/s, both of which meet the requirement for medical diagnostics. These findings shed light on the exploration of innovative bismuth-based hybrid perovskites for high-performance X-ray detection.
Membrane-based separation is a promising technology to eliminate water impurities from the oil phase. However, it remains a great challenge to separate water from highly emulsified viscous oil owing to the high stability of the water droplets in oil. Herein we report a surface wettability engineering on an alumina ceramic membrane to achieve an efficient separation of a water-in-oil (W/O) emulsion. Silanes with different carbon chain lengths and fluorinated status were introduced to endow the alumina membrane with different surface wettabilities. While all the modified membranes exhibited excellent separation of the W/O without Span 80 (surfactant), the one with amphiphobic wettability and lowest surface energy failed to separate the Span 80 stabilized W/O. The presence of Span 80 reduced the interfacial tension of water droplets, making them easier to deform and penetrate the modified membrane with the lowest surface energy. It reveals that engineering proper surface wettability is the key to separating the oil and water phases. Besides, the modified membranes maintained decent separation performance and stability under long-term run separation of the emulsified W/O.
Exhaled ammonia (NH3) can be used as a crucial biomarker of kidney and liver diseases. However, the high humidity in the detection conditions remains a challenge for accurate detection by gas sensors. Herein, a copper-based metal-organic framework (CH3-Cu-BTC) with methyl (CH3-) functionalization of trimesic acid was synthesized for NH3 colorimetric sensing. The CH3-Cu-BTC exhibited a strong response for 5 ppm NH3 with high selectivity under high relative humidity (75% RH). Density functional theory (DFT) simulations indicated that the NH3 molecules interacted more strongly with CH3-Cu-BTC than H2O molecules did, and the corresponding color switching was attributed to the lone-pair electron in NH3 changing the coordination environment of Cu2+ ions, leading to an obviously visible color switching response from ruby green to blue. Based on the tailor-made pore chemistry, the precise detection of trace amounts of NH3 in exhaled air was realized through functionalized MOF materials. The strategy used in this study not only offers a new pathway for the rapid detection of low concentration NH3 under humid conditions, but also shows a method for early respiration diagnosis of kidney and liver diseases.
The physicochemical properties of transition metal dichalcogenides (TMDs) are highly related to their structures and usually stable in air. However, under certain conditions they could be transformed into different structures due to oxidation. Considering this, various materials with fascinating structures have been explored by oxidation strategies, which possess novel properties and great potential in various applications such as solar batteries, hydrogen evolution reaction (HER) catalysts, and field effect transistors (FET). In this review, we systematically summarize the atomic structures of TMD oxidized variants and the corresponding fabrication approaches. Utilizing various characterization methods, the chemical components of TMD oxidized variants are illustrated. Furthermore, we expound the promising applications of the oxidized variants. This review is expected to provide a new insight for preparing precise materials at the atomic level through corresponding oxidation strategies.
Side reactions and dendrite growth triggered by the unstable interface and inhomogeneous deposition have become the biggest obstacle to the commercialization for lithium metal batteries. In this study, a highly-chlorinated organic-inorganic hybrid interfacial protective layer is developed by rationally tuning the interfacial passivation and robustness to achieve the convenient and efficient Li metal anode. The polyvinyl chloride (PVC) can effectively resist water and oxygen, which is confirmed by density functional theory. The organic-dominant solid electrolyte interphases (SEI) with lithium chloride are investigated by the X-ray photoelectron spectroscopy (XPS) with little mineralization of oxide, such as Li2O and Li2CO3. With such artificial SEI, a uniform and dense lithium deposition morphology are formed and an ultra-long stable cycle of over 500 h are achieved even at an ultra-high current density of 10 mA/cm2. Moreover, the simple and convenient protected anode also exhibits excellent battery stability when paired with the LiNi0.8Co0.1Mn0.1O2 (NCM811) and LiFePO4 (LFP) cathode, showing great potential for the commercial application of lithium metal batteries.
Molecular ferroelectrics have attracted much attention because of their excellent piezoelectricity, mechanical workability, and second harmonic effect. Here, we successfully prepared two molecular ferroelectrics 1,5–3.2.2-HdabcniX (X = ClO4−, 1; ReO4−, 2) by reactions of a quasi-spherical amine 1,5-diazabicycle[3.2.2]nonane (1.5–3.2.2-dabcn) with HX aqueous solution. Compounds 1 and 2 undergo high-temperature phase transitions at 381 K (1) and 396 K (2). Before and after the phase transition, they crystallize in the polar point group mm2, and the centrosymmetric point groups mmm and 4/mmm, respectively. According to Aizu rules, these two compounds experience mmmFmm2 and 4/mmmFmm2 type ferroelectric phase transitions, respectively. The ferroelectricity of both compounds is well expressed in their polycrystalline film at room temperature with low coercive voltages of 13 V for 1 and 25 V for 2. Using piezoelectric force microscopy (PFM), the 180° anti-parallel ferroelectric domains and the reversible polarization switching can be clearly observed in 1 and 2. This high-temperature molecular ferroelectric material has great application potential in flexible materials, biomechanics, intelligent wearables and other fields.
All-solid-state lithium batteries (ASSLBs) based on sulfide electrolytes promise next-generation energy storage with high energy density and safety. However, the sulfide electrolytes suffer from phase instability and sluggish interfacial charge transport when pairing with layered oxide cathodes at high voltages. Herein, a simple and efficient strategy is proposed using two-dimensional Ti3C2T MXene as starting material to in-situ construct a 15 nm Li2TiO3 layer on a typical oxide cathode, LiCoO2. The in-situ transformation of Ti3C2T into Li2TiO3 layer occurs at a low temperature of 500 ℃, avoiding the phase deterioration of LiCoO2. The thin Li2TiO3 layer is Li+ conducting and electrochemically stable, thereby preventing the interfacial decomposition of sulfide electrolytes induced by LiCoO2 at high voltages and facilitating Li+ transport at the interface. Moreover, Li2TiO3 can stabilize the layer structure of LiCoO2 at high voltages. Consequently, the sulfide-based ASSLB using LiCoO2@Li2TiO3 cathode can operate stably at a high voltage of up to 4.5 V (vs. Li+/Li), delivering an outstanding initial specific discharge capacity of 138.8 mAh/g with a high capacity retention of 86.2% after 100 cycles at 0.2 C. The in-situ transformation strategy may also apply to other MXenes, offering a general approach for constructing other advanced lithiated coatings for oxide cathodes.
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