Latest ArticlesLithium-halogen batteries (LHBs), including lithium iodide (Li-I2) and lithium bromide (Li-Br2) batteries, are receiving more attention for offering high energy density and excellent kinetic performance. However, LHBs commercialization is seriously hindered by the high solubility of halides, causing lower capacity and poor cyclability. This research covers the fabrication of a highly stable cathode of amorphous carbon coated CMK-3/LiI/LiBr nanocomposite for metal lithium batteries. The nanopores and coated layer can physically trap the dissolution of active materials. The amorphous carbon generated from polyacrylonitrile carries abundant nitrogen heteroatoms for the stable anchorage of halogens and halides via strong chemical adsorption. In addition, iodine can act as a complexing agent with bromine to reduce solvation energy. Consequently, the as-prepared CMK-3/LiI/LiBr/carbon (CIBP) nanocomposite cathode demonstrates an ultra-high reversible capacity of 407.4 mAh/g at the current density of 1.0 C performing up to 300 stable cycles.
Graphitic carbon nitride (g-C3N4) has been widely studied as a visible light responsive photocatalyst in recent years, due to its facile synthesis, low cost, high stability, and appropriate bandgap/band positions. In this review, we firstly introduce and compare various exfoliation approaches of bulk g-C3N4 into ultrathin g-C3N4 nanosheets. Then, many modification strategies of g-C3N4 nanosheets are also reviewed, including heterojunction construction, doping, defect control, and structure design. Thereafter, the charge transfer mechanism in g-C3N4 nanosheets based heterojunctions is present, e.g., Z-scheme, S-scheme and other forms. Besides, the photocatalytic applications of g-C3N4 nanosheets based photocatalysts are summarized including environmental remediation, energy generation and storage, organic synthesis, and disinfection. This review ends with a summary and some perspectives on the challenges and new directions in exploring g-C3N4 nanosheets-based photocatalysts.
Electrocatalytic production of hydrogen peroxide (H2O2) by two-electron oxygen reduction reaction (2e– ORR) under acidic condition has been considered to have great application value. Co nanoparticles (CoNPs) coupled with N-doped carbon are a class of potential electrocatalysts. The effective strategies to further enhance their performances are to improve the active sites and stability. Herein, the material containing ultrafine CoNPs confined in a nitrogen-doped carbon matrix (NC@CoNPs) was synthesized by pyrolyzing corresponding precursors, which was obtained through regulating the topological structure of ZIF-67/ZIF-8 with dopamine (DA). The DA self-polymerization process induced the formation of CoNPs with smaller sizes and formed polydopamine film decreased the detachment of CoNPs from the catalyst. High density of Co-Nx active sites and defective sites could be identified on NC@CoNPs, leading to high activity and H2O2 selectivity, with an onset potential of 0.57 V (vs. RHE) and ~90% selectivity in a wide potential range. An on-site electrochemical removal of organic pollutant was achieved rapidly through an electro-Fenton process, demonstrating its great promise for on-site water treatment application.
Chemotherapy combined with photodynamic therapy has emerged as a promising strategy for cancer treatment. However, simultaneously delivering chemotherapeutic drugs and photosensitizers and precisely adjusting the ratio of the two components as needed remains a challengeable task. Herein, novel supramolecular nanoparticles (donated as BODIPY-CPT-NPs) for chemo-photodynamic combination cancer therapy are constructed from a glutathione-responsive camptothecin-based prodrug, BODIPY photosensitizer, and dimacrocyclic host molecule through orthogonal host-guest recognitions and co-assembly. With this strategy, the ratio of prodrugs and photosensitizers in nanoparticles can be easily and precisely controlled as needed. Benefiting from the strong host-guest interactions and stable self-assembly, the nanoparticles exhibit excellent stability and photobleaching resistance. Furthermore, camptothecin can be released from nanoparticles for chemotherapy in the presence of reduction agent and single oxygen can be efficiently generated for PDT with light irradiation. The combined effects of the BODIPY-CPT-NPs have been verified in CT26 and HeLa cancer cells.
Oxygen-isotopic labelings play important roles in identifying and understanding chemical and biological processes. Direct C=O to C=18O or C=17O conversion in a single step leading to labeled compounds can alleviate synthetic burdens without the need for resynthesis. Here we describe a photocatalytic oxygen-isotopic labeling protocol that can efficiently and selectively install 18O and 17O on carbonyls of ketones and aldehydes via oxygen isotope exchange with oxygen-isotopic waters (H218O or H217O) as the sources of oxygen isotopes, in which light and oxygen-enabled sodium alkanesulfinates catalyzed this process. This strategy was extended to the in-situ formed ketones from the photocatalytic aerobic oxidation of alkyl arenes and secondary alcohols. Furthermore, reduction of the oxygen-isotopically labeled aldehydes with NaBH4 provided the corresponding oxygen-isotopically labeled primary alcohols. We believe that the oxygen-isotopically labeling method will be widely used in chemistry, biology and medicine fields.
Kirsten rat sarcoma viral oncogene homolog (KRAS)–phosphodiesterase-delta (PDEδ) is a promising target for antitumor drug discovery. Herein, highly efficient and environmentally sensitive fluorescent probes of PDEδ (DS-Probes) were rationally designed. As compared with the reported PDEδ probes, DS-Probes showed higher binding affinity and selectivity, which were able to conveniently and efficiently label PDEδ in live cells as well as tumor tissues. Therefore, these fluorescent probes are expected to facilitate PDEδ-based mechanism elucidation, drug discovery and pathologic diagnosis.
Direct synthesis of H2O2 from H2 and O2 via heterogeneous catalysis is an environmentally friendly and atomically economic alternative to the traditional anthraquinone oxidation (AO) process. Optimizing the electronic and geometric structures of the active metals to break the current limitations of hydrogenation rate and H2O2 selectivity is a promising and challenging topic. In this study, a series of Pd-Au bimetallic catalysts supported on TiO2 with a metal loading of 3.0 wt% and a constant Pd/Au molar ratio (Pd:Au = 2:1) were prepared. The catalysts were reduced in H2 at different temperatures (473, 573 and 673 K), and their catalytic activity for the direct H2O2 synthesis were evaluated at 283 K and 0.1 MPa. H2 reduced Pd-Au catalysts exhibited superior performance in direct H2O2 synthesis. The maximum H2O2 selectivity of 87.7% and H2O2 yield of 3116.4 mmol h−1 gPd−1 were achieved over the Pd2.0Au1.0-573 catalyst with a H2 conversion of 12.8%. The tailored local chemical environment caused by H2 reduction creates a balanced ratio of Pd0 and PdOx sites, thus improving the selectivity towards H2O2. This work developed an effective strategy for fabrication of highly active and stable Pd-based H2O2 synthesis catalysts with high H2O2 yield.
The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction (OER) is a prerequisite for efficient water electrolysis. Herein, we develop a broccoli-like Ni3S2@NiFePx (Ni3S2@NFP) catalyst on nickel foam (NF) via a sequential two-step layer-by-layer assembly electrodeposition method. X-ray diffraction, in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition. The reconstruction of double layer Ni3S2@NFP facilitates the formation of the active (oxy)hydroxides, which is modulated by the dual anionic layer with mixed sulfate and phosphate ions. As a result, the obtained Ni3S2@NFP electrode exhibits low overpotential (329 mV) and long-term durability (~500 h) for OER at current density of 500 mA/cm2. Moreover, the self-supported Ni3S2@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device (AEMWE). This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance.
Molybdenum disulfide (MoS2) has shown significant promise as an economic hydrogen evolution reaction (HER) catalyst for hydrogen generation, but its catalytic performance is still lower than noble metal-based catalysists. Herein, a silver nanoparticles (Ag NPs)-decorated 1T/2H phase layered MoS2 electrocatalyst grown on titanium dioxide nanorod arrays (Ag NPs/1T(2H) MoS2/TNRs) was prepared through acid-tunable ammonium ion intercalation. Taking advantage of MoS2 layered structure and crystal phase controllability, as-prepared Ag NPs/1T(2H) MoS2/TNRs exhibited ultrahigh HER activity. As-proposed strategy combines facile hydrogen desorption (Ag NPs) with efficient hydrogen adsorption (1T/2H MoS2) effectively circumventes the kinetic limitation of hydrogen desorption by 1T/2H MoS2. The as-prepared Ag NPs/1T(2H) MoS2/TNRs electrocatalyst exhibited excellent HER activity in 0.5 mol/L H2SO4 with low overpotential (118 mV vs. reversible hydrogen electrode (RHE)) and small Tafel slope (38.61 mV/dec). The overpotential exhibts no obvious attenuation after 10 h of constant current flow. First-principles calculation demonstrates that as-prepared 1T/2H MoS2 exhibit a large capacity to store protons. These protons can be subsequently transferred to Ag NPs, which significantly increases the hydrogen coverage on the surface of Ag NPs in HER process and thus change the rate-determining step of HER on Ag NPs from water dissociation to hydrogen recombination. This study provides a unique strategy to improve the catalytic activity and stability for MoS2-based electrocatalyst.
Anti-counterfeiting labels with various fluorescent colors are of great importance in information encryption-decryption, but are still limited to static information display. Therefore, it is urgent to develop new materials and encryption-decryption logic for improving the security level of secret information. In this study, an organohydrogel made up of poly(N,N-dimethylacrylamide) (pDMA) hydrogel network and polyoctadecyl methacrylate (pSMA) organogel network that copolymerized with two fluorophores, 6-acrylamidopicolinic acid moieties (6APA, fluorescent ligand) and spiropyran units (SPMA, photochromic monomer), was prepared by a two-step interpenetrating method. As UV light of 365 nm and 254 nm can both cleave Cspiro-O bonds of SPMA, and the green fluorescence of 6APA-Tb3+ can only be excited by 254 nm light, the organohydrogel displays yellow and red under the irradiation of 254 nm and 365 nm, respectively. In addition to wavelength selectivity, these two fluorophores are thermal-responsive, leading to the fluorescence variation of the organohydrogel during heating process. As a result, secret information loaded on the organohydrogel can be decrypted by the irradiation of UV light, and the authenticity of the information can be further identified by thermal stimulation. Our fluorescent organohydrogel can act as an effective anti-counterfeiting label to improve the information security and protect the information from being cracked.
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