RESUMEN
Binders are crucial for maintaining the mechanical stability of the electrodes. However, traditional binders fail to adequately buffer the volume expansion of Zn2SiO4 anode, causing electrode contact failure and considerable capacity loss during cycling. In this study, we propose a simple and effective solution to address these challenges through a combined strategy of hollow structure design and the introduction of an aqueous lithium poly(acrylic acid) (LiPAA) binder. Hollow structures can shorten ion-transfer distance and accommodate volume change outside. The excellent adhesion of the LiPAA binder created a secure connection between the active Zn2SiO4 particles, conductive additives, and the current collector, which enhanced the mechanical stability and integrity of the electrode. As a result of these positive factors, a Zn2SiO4 electrode using LiPAA as a binder can deliver an excellent capacity of 499 mAh g-1 at a high current density of 5 A g-1 and a long life span of 1000 cycles at 1 A g-1 with a capacity retention of 98%, which significantly outperforms other binders. As demonstrated by ex situ X-ray diffraction and ex situ X-ray absorption spectroscopy, the storage of lithium ions in Zn2SiO4 follows a dual conversion-alloying mechanism, using Zn as the redox center. In this process, Zn is first reduced to metallic Zn and then forms a LiZn alloy upon lithium-ion insertion. This work shows that LiPAA offers a promising approach to improve the cycling longevity of conversion and alloying anodes in Li-ion batteries.
RESUMEN
The electrification of heavy-duty transport and aviation urgently requires new strategies to develop high-rate lithium-ion batteries (LIBs) whose performance fundamentally relies on electrode materials. However, commercially available graphite anodes still suffer from slow kinetics of lithium-ion diffusion and severe safety concerns of lithium plating when achieving the high-rate use goal. Herein, taking Ti3C2Tx as an example, it is demonstrated that N and S co-doping in Ti3C2Tx results in a high-rate MXene anode for LIBs. Nitrogen doping not only flattens the MXene layers and expands the interlayer spacing but also increases the Ti valence state change ability. As evidenced by density functional theory calculations, the diffusion barriers of S-containing Ti3C2Tx MXenes are lower than those of the S-free counterpart, suggesting that S plays an essential role in achieving high-rate performance. Therefore, the N and S co-doped Ti3C2Tx anode in LIBs exhibited excellent performance with a reversible capacity of 113.8 mA h g-1 at a rate of 3C and â¼89% capacity retention after 1000 charge/discharge cycles. The high capacity is attributed to the change in the oxidation states of both Ti and O elements, and the tiny volume change within â¼0.6% upon the stable charging/discharging process accounts for the good capacity retention. When paired up with a LiFe0.5Mn0.5PO4 cathode, the full cell delivers a reversible capacity of 134 mA h g-1 after 1000 cycles at a high rate of 1C. The demonstration of N and S co-doped Ti3C2Tx MXenes in this work may offer a feasible approach for high-rate intercalation anode materials.
RESUMEN
Joubert syndrome (JBTS) is a class of heterogeneous ciliopathy genetically associated with CPLANE1 mutations. The characteristics of clinical phenotypes and CPLANE1 variants were analyzed in a 2-month-old patient. A 2-month-old patient with JBTS was diagnosed after clinical evaluation including family history, physical examination, cerebral MRI, ultrasonography imaging, VEGG, ocular fundus examination, and comprehensive blood and urine testing. Whole exome sequencing (WES) was performed to detect CPLANE1 variants, and Sanger sequencing was used to confirm the variants. This JBTS patient presented with oculomotor apraxia, dysregulation of breathing pattern, and ataxia. MRI revealed poor continuity of cerebelli, batwing appearance, and molar tooth sign. This patient was noted with abnormal hematology, dysregulation of hepatic function, thyroid function, immunity, and renal function, and encephalopathy. CPLANE1 (c.8948dupT (p.P2984Tfs*7) and c.247G > T (p.G83X)) variants were noticed in the patient as a pathogenic variant and caused autosomal recessive inheritance. The JBTS patient with mutations in CPLANE1 (c.8948dupT (p.P2984Tfs*7) and c.247G > T (p.G83X)) developed JBTS phenotypes. The novel CPLANE1 c.8948dupT (p.P2984Tfs*7) variant will assist clinicians and geneticists in reaching a precise diagnosis for JBTS.
RESUMEN
By means of a pipe's inner surface grinding, a single-phase nanostructured austenite was formed on the surface of an AISI 304 stainless steel. The electrochemical corrosion behavior was compared with a coarse-grained counterpart of identical surface roughness. Experimental results show that the nanostructured austenite shows a higher pitting potential and a wider passivation interval than those of its coarse-grained counterpart. The enhanced corrosion resistance was attributed to the fast diffusion of Cr within the nanostructure and, hence, the formation of a thicker passive film to efficiently protect the surface against the ion attack. This work provides insights into a simple processing method to improve the surface strength and pitting resistance of stainless steel.
RESUMEN
As a rapidly growing family of 2D transition metal carbides and nitrides, MXenes are recognized as promising materials for the development of future electronics and optoelectronics. So far, the reported patterning methods for MXene films lack efficiency, resolution, and compatibility, resulting in limited device integration and performance. Here, a high-performance MXene image sensor array fabricated by a wafer-scale combination patterning method of an MXene film is reported. This method combines MXene centrifugation, spin-coating, photolithography, and dry-etching and is highly compatible with mainstream semiconductor processing, with a resolution up to 2 µm, which is at least 100 times higher than other large-area patterning methods reported previously. As a result, a high-density integrated array of 1024-pixel Ti3 C2 Tx /Si photodetectors with a detectivity of 7.73 × 1014 Jones and a light-dark current ratio (Ilight /Idark ) of 6.22 × 106 , which is the ultrahigh value among all reported MXene-based photodetectors, is fabricated. This patterning technique paves a way for large-scale high-performance MXetronics compatible with mainstream semiconductor processes.
RESUMEN
MXenes represent an emerging family of two-dimensional materials of transition metal carbides/carbonitrides terminated with functional groups like -O, -OH, and -F on the chemically active surface of MX slabs. As a member of the family, Nb2CTx exhibits superior lithium storage capacity over most of the other MXenes as anode materials in lithium-ion batteries (LIBs). However, an in-depth understanding of the charge storage mechanism is still lacking so far. Here, through combining complementary experiments and density functional theory calculations, we provide insights into the (de)lithiation process. Specifically, Nb2CTx with dominant -O functional groups stores charge as a result of changes in the oxidation states of both transition metals Nb and O, which is supported by Bader charge analysis showing a significant change in the oxidation states of Nb and O upon lithiation. As monitored by ex situ X-ray diffraction, the interlayer spacing of Nb2CTx changes slightly upon lithium ion (de)intercalation, corresponding to a volume change of only 2.3% with a near zero-strain feature. By coupling with a LiFePO4/C cathode, the full cell presents superior rate capability and cycling stability as well. The insights into the charge storage mechanism of Nb2CTx in this work provide useful guidance for the rational design of MXene-based anode materials for high-performance LIBs.
RESUMEN
In this work, three types of dithiocarbamate (DTC)-modified starch derivatives including DTC starch (DTCS), DTC enzymolysis starch (DTCES) and DTC mesoporous starch (DTCMS) were developed, which showed the significant heavy metal adsorption performance. The adsorption ability of these three DTC modified starch derivatives followed the sequences: DTCMS>DTCES>DTCS. In single metal aqueous solutions, the uptake amount of heavy metal ions onto the modified starches obeyed the orders: Cu(II)>Ni(II)>Cr(VI)>Zn(II)>Pb(II). The adsorption mechanism was proved by the chelating between DTC groups and heavy metal ions through the pH effect measurements. A monolayer adsorption of Langmuir isotherm model for the adsorption of Cu(II) onto DTCMS was well fitted rather than the multilayer adsorption of Freundlich isotherm model. The adsorption kinetics of Cu(II) onto starch derivatives was found to be fit well with the pseudo-second-order model. Additionally, in the presence of EDTA, the adsorption ability and uptake amount of heavy metal ions onto these three DTC modified starch derivatives is identical with the results obtained in the absence of EDTA.
RESUMEN
In this paper, different starches were modified by diethylenetriamine. The native starch reacted with diethylenetriamine giving CAS, whereas the enzymatic hydrolysis starch was modified by diethylenetriamine producing CAES. Adsorption capacities of CAES for four acid dyes, namely, Acid orange 7 (AO7), Acid orange 10 (AO10), Acid green 25 (AG25) and Acid red 18 (AR18) have been determined to be 2.521, 1.242, 1.798 and 1.570 mmol g(-1), respectively. In all cases, CAES has exhibited higher sorption ability than CAS, and the increment for these dyes took the sequence of AO7 (0.944 mmol g(-1))>AO10 (0.592 mmol g(-1))>AR18 (0.411 mmol g(-1))>AG25 (0.047 mmol g(-1)). Sorption kinetics and isotherms analysis showed that these sorption processes were better fitted to pseudo-second-order equation and Langmuir equation. Chemical sorption mechanisms were confirmed by studying the effects of pH, ionic strength and hydrogen bonding. Thermodynamic parameters of these dyes onto CAES and CAS were also observed and it indicated that these sorption processes were exothermic and spontaneous in nature.