Latest ArticlesTuning the photoresponse of monolayer MoS2 could extend its potential application in many fields, however, it is still a challenge. In this study, CsPbBr3 nanoparticles were prepared and spin-coated on the surface of monolayer MoS2 to fabricate hybrid CsPbBr3/MoS2 photodetectors. By combing the photoelectrical property of the CsPbBr3, the synergistic effect has been systematically studied from its carrier mobility, photoresponse and detectivity. It was found that nanofilm-coating of CsPbBr3 would impede the photoelectric performance due to the electron-hole recombination facilitated by the defects at the interface of CsPbBr3 and MoS2 films. While the nanoparticles decorating was observed to significantly improve the conductivity of the monolayer MoS2, which also increased the on/off ratio of the MoS2 transistor from 8.2 × 103 to 4.4 × 104, and enhanced the carrier mobility from 0.090 cm2 V−1 s−1 to 0.202 cm2 V−1 s−1, ascribing to a mixed electron recombination-injection process. Furthermore, the CsPbBr3 nanofilm would decrease the responsivity to 136 and 178 A/W under the light wavelength of 400 and 500 nm, respectively, while decorating CsPbBr3 nanoparticles improve the photoresponse to 948 and 883 A/W with the detectivity at the level of 1011 Jones. This work may provide an easy and cost-efficient way to tune the photoresponse of MoS2 photodetectors.
Cycloaddition of CO2 and epoxide into cyclic carbonate is one of the most efficient ways for CO2 conversion with 100% atom-utilization. Metal–organic frameworks are a kind of potential heterogeneous catalysts, however, high temperature, high pressure, and high-purity CO2 are still required for the reaction. Here, we report two new Zn(Ⅱ) imidazolate frameworks incoporating MoO42– or WO42– units, which can catalyse cycloaddition of CO2 and epichlorohydrin at room temperature and atomospheric pressure, giving 95% yield after 24 h in pure CO2 and 98% yield after 48 h in simulated flue gas (15% CO2 + 85% N2), respectively. For comparison, the analogic Zn(Ⅱ) imidazolate framework MAF-6 without non-3d metal oxide units showed 71% and 33% yields under the same conditions, respectively. The insightful modulation mechanisms of the MoO42– unit in optimizing the electronic structure of Zn(Ⅱ) centre, facilitating the rate-determined ring opening process, and minimizing the reaction activation energy, were revealed by X-ray photoelectron spectroscopy, temperature programmed desorption and computational calculations.
Ion transport plays an important role in energy conversion, biosensors, and a variety of biological processes. Carbon nanotubes, especially for the carbon nanotubes arrays with controlled vertically aligned structures, have displayed great potential as a promising material for regulating ion transport behaviors in the applications of the nanofluidic devices and osmotic energy conversion. Herein, we demonstrate the thermo-controlled ion transport system through the vertically aligned multiwall carbon nanotubes arrays membrane modified by the thermo-responsive hydrogel in a simple and reliable way. The functional carbon nanotubes backbone with the inherent surface charge and interstitial channels structure renders the system improved ion transport behaviors and well controlled switching property by thermo. Based on the integrated properties, the energy output from osmotic power in this system could be regulated by the reversible temperature switches. Moreover, it can realize a higher osmotic energy conversion property regulated by the thermos, which may extend the practical application in the future. The system that combines intelligent response with controlled ion transport behaviors and potential osmotic energy utilizations presents a valuable paradigm for the use of carbon nanotubes and hydrogel composite materials and provides a promising way for applications of nanofluidic devices.
Reversible protonic ceramic cells (RPCCs) show great potential as new-generation energy conversion and storage devices. However, the mature development of RPCCs is seriously hindered by the inactivity and poor stability of air electrodes exposed to concentrated vapor under operating conditions. Herein, we report a high-entropy air electrode with the composition BaCo0.2Fe0.2Zr0.2Sn0.2Pr0.2O3- (BCFZSP), which shows integrated electronic, protonic and oxygenic conduction in a single perovskite phase and excellent structural stability in concentrated steam. Such triple conduction can spread the electrochemically active sites of the air electrode to the overall electrode surface, thus optimizing the kinetics of the oxygen reduction and evolution reactions (0.448 Ω cm2 of polarization resistance at 550 ℃). As-prepared RPCCs with a BCFZSP air electrode at 600 ℃ achieved a peak power density of 0.68 W/cm2 in fuel-cell mode and a current density of 0.92 A/cm2 under a 1.3 V applied voltage in electrolysis mode. More importantly, the RPCCs demonstrate an encouragingly high stability during 120 h of reversible switching between the fuel-cell and electrolysis modes. Given their excellent performance, high-entropy perovskites can be promising electrode materials for RPCCs.
The accurate delivery of nanoparticles and organic small molecule drugs remains a serious challenge in nanoparticle-based tumor therapy. Dual-targeted therapy combining tumor cell targeting and organelle targeting is an effective solution. Here, an anticancer nanoformulation accurate delivery system was prepared using hyaluronic acid (HA) targeting CD44 receptors on the surface of tumor cells and IR780 iodine (IR780) targeting mitochondrial for delivery. The system is based on an ultra-small Janus structured inorganic sensitizer TiO2-x@NaGdF4 nanoparticles (TN NPs) prepared by one-step pyrolysis, further loaded with organic small molecule acoustic sensitizer IR780 and mitochondrial hexokinase Ⅱ inhibitor lonidamine (LND), followed by encapsulation of HA. Ultra-small size nanoparticles exhibit strong tissue penetration, tumor inhibition and in vivo metabolism. Under ultrasound radiation, TN NPs and IR780 could produce a synergistic effect, effectively increased the efficiency of reactive oxygen species (ROS) production. Meanwhile, the released IR780 could smoothly target the mitochondria, and the ROS produced by IR780 can destroy the mitochondrial structure and disrupt the mitochondrial respiration. LND could inhibit the energy metabolism of tumor cells by reducing the activity of hexokinase Ⅱ (HK Ⅱ), which further accelerates the process of apoptosis. Furthermore, since the Janus structure allows the integration of multifunctional components into a single system, TN NPs can not only serve as an acoustic sensitizer to generate ROS, but the Gd element contained can also act as the nuclear magnetic resonance (MR) imaging contrast agent, suggesting that the nanoformulation can enable imaging-guided diagnosis and therapy. In conclusion, a new scheme to enhance sonodynamic therapy (SDT) and chemotherapy synergistically is proposed here based on ultra-small dual-targeted nanoformulation with Janus structure in the ultrasound radiation environment.
Compared with solid alkali metal anodes (Li, Na, K), liquid metal anodes (LMAs) could enable high-energy batteries due to their unique advantages, such as self-healing property and no dendrites. Among LMAs, liquid Na-K alloy anode has become a hotspot due to its high theoretical capacity, low redox potential and formation at room temperature (RT). However, it is challenging to utilize liquid Na-K alloy directly and independently as an electrode; and the high surface tension makes it more difficult to immerse into porous current collectors at RT. Herein, an amorphous hollow carbon film (AHCF) consisting of hollow spheres with significant surface defects has been designed to quickly infiltrate Na-K liquid alloy into the hollow carbon film at RT, forming a composite electrode (Na-K@AHCF). The symmetric cell with Na-K@AHCF could exhibit a cycle lifespan up to 400 h at 0.1 mA/cm2 and achieve stable stripping/deposition even at 5 mA/cm2. When matching with cathode material of sulfurized polyacrylonitrile (SPAN), the obtained K-S full cell exhibits good cycle stability and rate performance.
Mesoporous silica hollow spheres with a homogenous and high content distribution of Fe and Co were synthesized by a facile one-pot hydrothermal process. The sub-nanometer bimetallic components inside the silica framework facilitate the stable fixation and the open accessibility to active sites. The co-doped Fe/Co in the spheres showed excellent peroxidase-like activity and much higher catalytic performance than their monometallic-supported spheres. The synergistic effect between Fe and Co promotes the continuous formation of functional radicals during the oxidation process and thus accelerates the reaction rate. When used for colorimetric detection of hydrogen peroxide (H2O2), the Fe/Co incorporated silica hollow spheres show the capability of detection of H2O2 in a wide range (10-250 µmol/L) and with the low detection limit of 0.012 ppm.
Nickel–zinc (Ni–Zn) batteries hold a lot of promise for energy storage thanks to their high output voltage, plentiful Zn supply, and low toxicity. Achieving the facile preparation of high-performance cathodes at ambient temperature remains a challenge, it is however essential for practical applications. Here, in the present study, an efficient ultrasound-assisted one-step fabrication of CoNi double hydroxide (UA-CoNi DH) microspheres at room temperature that performs well as a cathode for Ni–Zn batteries was proposed. This designed ultrasound-assisted method induces the formation of metal double hydroxide with an elevation of interlayer spacing and bulk conductivity while maintaining the structure features of CoNi DH prepared without ultrasound assistance. As a result, the UA-CoNi DH as an electrode material displays highly enhanced electrochemical properties relative to CoNi DH prepared without ultrasound assistance. Benefitting from the improved performance of our UA-CoNi DH electrode, the Ni–Zn battery with UA-CoNi DH as the cathode (UA-CoNi DH//Zn) delivers a good specific capacity (202.36 mAh/g) and rate performance (70.49% capacity maintained at a 10-fold higher current), presenting more than 71.61% and 21.99% improvement relative to the CoNi DH//Zn battery, respectively. This work offers guidelines for constructing high-performance Ni–Zn battery cathodes in an open environment.
Alkaline hydrogen evolution reaction (HER) suffers from a sluggish kinetic, which requires the elaborate catalytic interface and micro-nanoscale architecture engineering of the electrocatalysts to accelerate the water dissociation and hydrogen evolution. Herein, the heterointerface engineering was proposed for promoting the alkaline HER by constructing the highly exposed Ru/RuS2 heterostructures homogeneously distributed on hollow N/S-doped carbon microspheres (Ru/RuS2@h-NSC). Benefited from the synergistic effect of heterointerfacial Ru/RuS2, the high accessibility of the active sites on both inner and outer surface of mesoporous shells and the efficient mass transport, Ru/RuS2@h-NSC affords a remarkable catalytic performance with an overpotential of 26 mV@10 mA/cm2 for alkaline HER, outperforming most of the state-of-the-art catalysts. Further applying Ru/RuS2@h-NSC and its oxidized derivate for the overall alkaline water splitting, the required cell voltage is much lower than that of the commercial Pt/C||RuO2 pair to achieve the same current density. Our study may allow us to guide the design of micro-nanoreactors with optimal catalytic interfaces for promising electrocatalytic applications.
The integration of lanthanide (Ln) ions and polyoxoniobates (PONbs) is challenging, and the known Ln-substituted PONbs are still scarce. This work introduces high-nuclear iso-Ln-oxo clusters into the PONb system. The first series of high-nuclear Ln-oxo clusters encapsulated heterometallic polyoxoniobates H9[Na(H2O)4][Cu(en)2]10{Ln6(μ3-OH)6(SiNb18O54)3}·18H2O (1-Ln, en = ethylenediamine, Ln = Dy, Gd, Tb, Ho, Er, Tm, Yb, Lu) based on flower-like {Ln6(μ3-OH)6(SiNb18O54)3} ({Ln6Si3Nb54}) clusters have been successfully synthesized via one-pot hydrothermal synthesis strategy. The flower-like polyoxoanion {Ln6Si3Nb54} is consisted of three heteropolyoxoniobate {SiNb18O54} clusters and one unique planar equilateral triangle-shaped {Ln6(μ3-OH)6} cluster, which presents the highest nuclear iso-Ln-oxo cluster in PONb chemistry. In {Ln6(μ3-OH)6} cluster, each pair of μ3-OH groups link three Dy3+ ions to form a small approximate equilateral triangle-shaped {Dy3(OH)2} cluster. Furthermore, the three {Dy3(OH)2} clusters comprise a bigger approximate equilateral triangle-shaped {Dy6(μ3-OH)6} cluster. The reported hexanuclear {Ln6} cluster skeletons are mostly octahedral, however, such equilateral triangle-shaped skeleton of the hexanuclear Ln-oxo cluster is first observed. The 1-Dy exhibits good water vapor adsorption capacity and ferromagnetic properties.