Latest ArticlesSupported Pd based catalysts are considered as the efficient candidates for low-carbon alkane oxidation for their outstanding capability to break C-H bond. Whereas, the irreversible deactivation of Pd based catalysts was still frequently observed. Herein, we reinforced the extruded Pd nanoparticles with quantitive Pt to assemble the evenly distributed PdPt nanoalloy onto ferrite perovskite (PdPt-LCF) matrix with strengthened robustness of metal/oxide support interface. We further co-achieved the enhanced performance, anti-overoxidation as well as resistance of vapor-poisoning in durability measurement. The operando X-ray photoelectron spectroscopy (O-XPS) combined with various morphology characterizations confirms that the accumulation of surface deep-oxidation species of Pd4+ is the culprit for fast activity loss in exsolved Pd system, especially at high temperature of 400 ℃. Conversely, it could be completely suppressed by in-situ alloying Pd with equal amount of Pt, which helps maintain the metastable Pd2+/Pd shell and metallic solid-solution core structure. The density function theory (DFT) calculations further buttress that the dissociation of CH was facilitated on alloy/perovskite interface which is, on the contrary, resistant toward O–H bond cleavage, as compared to Pd/perovskite. Our work suggests that the modification of exsolved metal/oxide catalytic interface could further enrich the toolkit of heterogeneous catalyst design.
MOF-based core-shell structures with high surface area, abundant active sites, and broad absorption bands are viable alternatives to traditional single-component photocatalysts. In this report, we describe the design and construction of delicate Ag nanowires@NH2-UiO-66 with a core-shell structure for use as photocatalysts in imine synthesis under light. The optimized composites exhibited 80% imine production, which was higher than both MOF and Ag NWs. The significant improvement in photocatalytic activity under light may be attributed to the plasmonic effect of silver nanowires and their core-shell structure, which promotes the separation of electron-hole pairs. Moreover, the photocatalytic activity of the core-shell nanostructure may provide valuable insight into the design and construction of MOF-based composite photocatalysts for oxidative coupling of amines.
Rechargeable aluminum batteries with multi-electron reaction have a high theoretical capacity for next generation of energy storage devices. However, the diffusion mechanism and intrinsic property of Al insertion into MnO2 are not clear. Hence, based on the first-principles calculations, key influencing factors of slow Al-ions diffusion are narrow pathways, unstable Al-O bonds and Mn3+ type polaron have been identified by investigating four types of δ-MnO2 (O3, O'3, P2 and T1). Although Al insert into δ-MnO2 leads to a decrease in the spacing of the Mn-Mn layer, P2 type MnO2 keeps the long (spacious pathways) and stable (2.007–2.030 Å) Al-O bonds resulting in the lower energy barrier of Al diffusion of 0.56 eV. By eliminated the influence of Mn3+ (low concentration of Al insertion), the energy barrier of Al migration achieves 0.19 eV in P2 type, confirming the obviously effect of Mn3+ polaron. On the contrary, although the T1 type MnO2 has the sluggish of Al-ions diffusion, the larger interlayer spacing of Mn-Mn layer, causing by H2O could assist Al-ions diffusion. Furthermore, it is worth to notice that the multilayer δ-MnO2 achieves multi-electron reaction of 3|e|. Considering the requirement of high energy density, the average voltage of P2 (1.76 V) is not an obstacle for application as cathode in RABs. These discover suggest that layered MnO2 should keep more P2-type structure in the synthesis of materials and increase the interlayer spacing of Mn-Mn layer for providing technical support of RABs in large-scale energy storage.
The electric field-induced irreversible domain wall motion results in a ferroelectric (FE) hysteresis. In antiferroelectrics (AFEs), the irreversible phase transition is the main reason for the hysteresis effects, which plays an important role in energy storage performance. Compared to the well-demonstrated FE hysteresis, the structural mechanism of the hysteresis in AFE is not well understood. In this work, the underlying correlation between structure and the hysteresis effect is unveiled in Pb(Zr, Sn, Ti)O3 AFE system by using in-situ electrical biasing synchrotron X-ray diffraction. It is found that the AFE with a canting dipole configuration, which shows a continuous polarization rotation under the electric field, tends to have a small hysteresis effect. It presents a negligible phase transition, a small axis ratio, and electric field-induced lattice changing, small domain switching. All these features together lead to a slim hysteresis loop and a high energy storage efficiency. These results offer a deep insight into the structure-hysteresis relationship of AFEs and are helpful for the design of energy storage material.
The photothermal therapy (PTT) has come across as a promising noninvasive therapeutic strategy for tumor treatment. However, low photothermal conversion efficiency (PCE) and hydrophobicity may impede the therapeutic efficacy of organic photothermal agents and an efficient PTT-agent must overcome these two major challenges. In this work, we developed a new strategy to promote higher PCE wherein the intermolecular hydrogen-bonding interaction between the single dye molecule and water facilitated the transformation of the absorbed energy into the heat. A hydrophilic squaraine dye (SCy1) with the second near-infrared region (NIR-II) absorption and extremely low emission were designed to exhibit much higher PCE than that of the analogues of pentamethine-dyes (PCy1, PCy2). The presence of the '–O−' at middle of squaric cycle enabled the intermolecular H-bonding formation between the SCy1 and water to promote the energy dissipation channel. Moreover, the introduction of long-chain phenylsulfonate groups helped in to improve the water solubility apart from serving as an additional means of further enhancing PCE through fluorescence quenching. Therefore, SCy1 with a squaraine backbone and long-chain sulfonate moieties revealed outstanding photothermal stability and anti-aggregation activity apart from showing exceptionally high PCE (74%) in water. SCy1 demonstrated excellent therapeutic efficacy when applied in the PTT treatment of tumor-bearing mice under a laser irradiation of 915 nm.
The blue-light-excitable phosphors play a crucial role in the high-performance white LEDs. Here, we report on two new Cu(Ⅰ) coordination network materials as yellow-emitting phosphors prepared by suitably expanded π-conjugated triazole ligands. Upon blue-light irradiation, these complexes exhibit efficient solid-state emission and enhanced photostability. Through incorporating the yellow phosphor and a commercial blue-green powder (BaSi2N2O2:Eu2+) with a blue LED chip, the phosphor-converted LED devices display remarkable white emission properties. The experimental results demonstrate that the Cu(Ⅰ) coordination network materials function as promising blue-light excitable phosphors with great application potential for full-spectrum white LEDs.
Melanoma is one of the most malignant skin tumors, whose high invasion is generally associated with BRAF gene mutation. Although new chemotherapeutic drugs, such as vemurafenib, have been developed to inhibit the growth of melanoma, these drugs are usually administered intravenously or orally, resulting in toxic side effects on major tissues and organs. Tetrahedral framework nucleic acids (tFNAs) are a novel type of DNA nanostructures with excellent biocompatibility and versatility which have been proven to penetrate through skin barrier with ease. In this study, we prepared tFNAs with vemurafenib and connected DNA aptamer AS1411 at the apex of tFNAs (AS1411-tFNAs/vemurafenib). On one hand, AS1411-tFNAs/vemurafenib could kill melanoma cells by blocking the mutated BRAF gene in vitro. Compared with free vemurafenib, AS1411-tFNAs/vemurafenib had no obvious toxicity to normal cells. On the other hand, AS1411-tFNAs could transfer vemurafenib to cross through the skin barrier and permeate into tumor tissues. In vivo, transdermal delivery of AS1411-tFNAs/vemurafenib could inhibit the growth of human A375 melanoma, whose inhibiting effect was stronger than intravenous administration of vemurafenib. These results demonstrated the application prospects of tFNAs combined with chemotherapeutic drugs in skin tumors.
Despite the synergy of immune checkpoint blockade (ICB) therapy and photodynamic therapy (PDT) holds great promise as countermeasures against breast cancer, exploring long-term or flexible short-time therapeutic strategies in "cold" tumors remains a great challenge. Here, we present a polyunsaturated fatty acid-doped liposomal hydrogel Lp(DHA)@CP Gel loaded with photosensitizer chlorin e6 (Ce6) and programmed death-ligand 1 antibody (αPD-L1) for flexible local photoimmunotherapy with merely single-dosed administration. The presence of polyunsaturated fatty acid (docosahexaenoic acid, DHA) doped in particle membrane endows liposomes with flexibly reactive oxygen species (ROS)-responsive release capability, which was attributed to the presence of abundant unsaturated groups. The αPD-L1 was repeatedly induced to in situ release in response to the PDT under photo-exposure. The immunogenic cell death (ICD) effect of PDT evoked "cold" breast tumor to "hot" one, and then assisted the cascade released αPD-L1 to synergistically boost the immunotherapy. After a single dose of peritumoral administration of Lp(DHA)@CP Gel, the on-demand treatment can maximize patient compliance and safety by adjusting therapeutic behaviors via a photo on-off switch. This work presents a flexible medication platform, showing promise in improving the objective response rate of ICB therapy and minimizing its systemic toxicity.
In the physiological environment, nanoparticles (NPs) interact with proteins to form a protein-rich layer on the surface which is called "protein corona". Understanding and analyzing the formation process of protein corona and protein corona-nanoparticles is of great significance for biological related nano research. Many separation techniques have been used to analyze the composition of protein corona, but in situ analysis of protein corona is still absent. With the development of detection technology, sum frequency generation (SFG) is an effective instrument to analyze the surface protein structure and dynamic changes of protein corona in situ. In this work the molecular mechanism and surface structure effect of the interaction between nanoparticles with surface protein corona (S-NPP) and phospholipid membrane were studied. When S-NPP interacts with phospholipid membrane, the bond affinity network formed by the binding water can stabilize S-NPP around the lipid bilayer. In this process, S-NPP can be found wrapped in the hydration shell. This ultimately leads to a more moderate interaction between particles and phospholipid membrane.
In this work, we designed and synthesized cationic carbon dots (CDs) with a size distribution of 1.6–3.7 nm, which exhibited dark blue fluorescence in the aqueous solution. Based on its excellent luminescence properties, we used it as an energy donor to construct a sequential artificial light-harvesting system (LHS) by employing the energy-matching dyes eosin Y disodium salt (EY) and sulforhodamine 101 (SR101), which could regulate the white light emission (Commission Internationale de lʼEclairage (CIE) coordinate: (0.30, 0.31)) with the energy transfer efficiency (ΦET) of 53.9% and 20.0%. Moreover, a single-step artificial LHS with white light emission (0.32, 0.28) can be constructed directly using CDs and dye solvent 43 (SR) with ΦET and antenna effect (AE) of 48.8% and 6.5, respectively. More importantly, CDs-based artificial LHSs were firstly used in photocatalytic of α-bromoacetophenone, with a yield of 90%. This work not only provides a new strategy for constructing CDs-based LHSs, but also opens up a new application for further applying the energy harvested in CDs-based LHSs to the field of the aqueous solution photocatalysis.
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