Latest ArticlesPhotoelectrochemical (PEC) water splitting is a promising technology to use solar energy. However, current metal oxides photoanode face the problem of sluggish water oxidation kinetic. In this study, we propose that the sluggish water oxidation process will cause slow mass transfer efficiency, which are rarely considered previously, especially at large bias and strong illumination. Mass transfer refers to the migration of reactants (like H2O and OH-) to the photoanode surface, reaction with holes and diffusion of products (like radical and O2) to the bulk of the electrode. If the migration and diffusion are not fast enough, the mass transfer will inhibit the increase of PEC activity. This problem will be more apparent for nanorod arrays (NRAs), where the space among the NRAs is related narrow. Herein, we solve this problem by decorating the surface of the photoanode by NiO clusters with Ni3+ state as water oxidation cocatalysts. This work studies the PEC process from the viewpoint of mass transfer and firstly demonstrates that mass transfer in NRAs structure can be promoted by using Ni-based water oxidation cocatalyst.
The rapid recombination of charge carriers in piezoelectric materials has always been the problem that limits their piezoelectric performance for removal of organic pollutants in water. Herein, we construct a piezoelectric BaTiO3/MoS2 (BTO/MS) that follows a type Ⅱ heterojunction charge transfer system to inhibit the recombination of electron-hole (e‒-h+) pairs, which is beneficial to the activation of peroxymonosulfate (PMS) for the removal of antibiotic ornidazole (ORZ) pollutants. The optimal ratio of BTO/MS for ORZ degradation under the piezo/PMS process is 13.9, 3.6, 62.1 and 2.0 times higher than that of the BTO/piezo, MS/piezo, (BTO/MS)/PMS and (BTO/MS)/piezo processes, respectively. The high efficiency charge separation in the piezoelectric heterojunction of BTO/MS promotes the activation of PMS, resulting in the synergy of pizeocatalysis and PMS oxidation during the process of ORZ degradation. This study provides an idea for enhancing piezo-activation of PMS by constructing heterojunctions in piezoelectric materials.
Encapsulation and controlled release of volatile molecules such as fragrances in a designed manner is important but challenging for the flavor and fragrance industry. Here, we report the tuning release of volatile molecules by postsynthetic modification of an amine-terminated metal-organic framework (MOF) MIL-101-NH2. By amidation, we obtained three MIL-101 MOFs, the trimethylacetamide-terminated TC-MIL-101, the benzamide-terminated BC-MIL-101, and the oxalic acid monoamide-terminated OC-MIL-101. All the MOFs can efficiently encapsulate volatile molecules. Moreover, we demonstrate that the release profile of volatiles can be widely tuned to sustain the release in several days to months and even over a year using different modified MIL-101 MOFs. We show that the release profiles are correlated with the binding energies between the guest volatiles and pores in MOFs. The pore diffusion and the synergistic transport are the rate-limiting step of the guest molecules from the modified MOFs.
Numerous nanocarriers have been currently developed for intracellular delivery. The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration. Thus, it becomes of utmost importance to conduct the intracellular trace of nanocarriers. Among many analytical techniques, surface enhanced Raman scattering (SERS) method is one of the current state-of-the-art techniques for cell visualization and trace. In this work, a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose. A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags. The results show that the designed system not only could deliver siRNA into cells for therapy, but also could realize SERS trace with high sensitivity and non-invasive features. The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.
Alzheimer's disease (AD) is a progressive and fatal neurodegenerative condition and the most prevalent cause of dementia. This disease is characterized by progressive cognitive impairment. The prevalence of AD is currently affecting more than 35 million people and is rising worldwide. No efficient therapy is currently available due to low drug potency and a number of various obstacles to delivery. Recent nanotechnological advancements have the potential to offer promising therapeutic options. Progress on nanomaterials as well as their applications in biomedicine is receiving increasing attention, especially the advantages of nanomaterial-based drug delivery systems. The aim of this review is to comprehensively summarize the latest developments in nanomaterial-based strategies for AD treatment, including nanoparticles, liposomes and other options for the delivery of therapeutic compounds and scaffolds for cell delivery strategies. Future research directions are also proposed. We hope this review can provide important information to guide the future development of nanomaterials in AD treatment.
The methanol oxidation reaction (MOR) is the limiting half-reaction in direct methanol fuel cell (DMFC). Although Pt is the most active single-metal electrocatalyst for MOR, it is hampered by high cost and CO poisoning. Constructing a Pt or Ru monolayer on a second metal substrate by means of galvanic replacement of underpotentially deposited (UPD) Cu monolayer has been shown as an efficient catalyst design strategy for the electrocatalysis of MOR because of the presumed 100% utilization of atoms and resistance to CO poisoning. Herein, we prepared one-dimensional surface-alloyed electrocatalyst from predominantly (111) faceted Au nanowires with high aspect ratio as the substrate of under-potential deposition. The electrocatalyst comprises a core of the Au nanowire and a shell of catalytically active Pt coated by Ru. Coverage-dependent electro-catalytic activity and stability is demonstrated on the Pt/Ru submonolayers on Au wires for MOR. Among all these catalysts, Au@PtML@RuML exhibits the best electrocatalytic activity and poisoning tolerance to CO. This presents a viable method for the rational catalyst design for achieving high noble-metal utilization efficiency and high catalytic performance.
A series of spirooxindole-ferrocene hybrids bearing five or four contiguous chiral centers were designed and synthesized via organocatalysis. In vitro protein binding and cellular proliferation assays suggested that compound 5d was the most potent mouse double minute 2 homolog (MDM2) inhibitor. In addition, mechanistic studies indicated that compound 5d suppressed MDM2-mediated p53 degradation, induced apoptosis and promoted oxidative damage. Molecular docking studies have suggested that 5d binds to MDM2 by mimicking the Trp23 and Leu26 residues of p53. This work can provide a basis for the development of novel multifunctional MDM2 inhibitors. The further exploration of more derivatives from this library and additional investigation of organocatalysis application in the development of new molecules may generate new potential lead compounds for cancer-targeted therapy.
Transition-metal oxides are considered to be a promising anode material for lithium-ion batteries (LIBs) due to their high capacities, low cost, and ease of synthesis. Herein, a hybrid nanosheet composed of uniform MoO2 nanoparticles (NPs) homogeneously immobilized on the reduced graphene oxide nanosheets (MoO2 NP@rGO) is first synthesized by a self-templating and subsequent calcination treatment. The unique two-dimensional hybridnanosheets provides several merits. rGO can be used as a favorable support for the loading of electrochemically active MoO2 NPs. Meanwhile, MoO2 NPs can effectively prevent the stacking of the rGO. The effective combination of MoO2 NPs and rGO nanosheets furnish additional electrochemically interfacial active sites for extra lithium ion storage. Noticeably, the as-fabricated hybrid nanosheets deliver a reversible capacity of 641 mAh/g after 350 cycles at a current density of 1000 mA/g with a good rate capability. The greatly enhanced lithium storage properties of MoO2 NP@rGO indicate the importance of elaborate construction of novel hybrid hierarchical structures.
Surface oxygen vacancy defects and metal deposition on semiconductor photocatalysts play a critical role in photocatalytic reactions. In this work, oxygen-deficient Bi2WO6 microspheres have been prepared by a facile ethylene glycol-assisted solvothermal method. Bi0 nanoparticles were reduced by in situ thermal-treatment on Bi2WO6 microspheres to obtain Bi0@Bi2WO6-x as well as maintaining the oxygen vacancies (OVs) under N2 atmosphere. Afterwards, photocatalytic NO oxidation removal activities of these photocatalysts were investigated under visible light irradiation and Bi0@Bi2WO6-x shows the best NO removal activity than other samples. The photogenerated charge separation and transfer are promoted by Bi0 nanoparticles deposited on the surface of semiconductor catalysts. OVs defects promote the activation of reactants (H2O and O2), thereby enhancing the formation of the active substance. Moreover, both OVs defects and Bi0 metal have the characteristics of extending light absorption and enhancing the efficient utilization of solar energy. Besides, the photocatalytic NO oxidation mechanism of Bi0@Bi2WO6-x was investigated by in situ FTIR spectroscopy for reaction intermediates and final products. This work furnishes insight into the synthesis strategy and the underlying photocatalytic mechanism of the surface-modified Bi0@Bi2WO6-x composite for pollutants removal.
Novel and efficient Mn(OAc)3·2H2O promoted radical addition-[4+1] cyclization relay of 3-indolymethanols and phosphites was disclosed, which afforded 1, 2-oxaphospholoindole derivatives in moderate to good yields. Based on the experimental and computational studies, a mechanism involving radical addition and intramolecular cyclization cascade was proposed.
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