Self-Matching Assembly of Chiral Gold Nanoparticles Leads to High Optical Asymmetry and Sensitive Detection of Adenosine Triphosphate.

To achieve chiral amplification, life uses small chiral molecules as building blocks to construct hierarchical chiral architectures that can realize advanced physiological functions. Inspired by the chiral amplification strategy of nature, we herein demonstrate that the chiral assembly of chiral gold nanorods (GNRs) leads to enhanced optical asymmetry factors (g-factors), up to 0.24. The assembly of chiral GNRs, dictated by structural self-matching, leads to g-factors with over 100-fold higher values than those of individual chiral GNRs, as confirmed by numerical simulations. Moreover, the efficient optical asymmetry of chiral GNR assemblies enables their application as highly sensitive sensors of adenosine triphosphate (ATP detection limit of 1.0 µM), with selectivity against adenosine diphosphate and adenosine monophosphate.

Honeycomb-Structured IrOx Foam Platelets as the Building Block of Anode Catalyst Layer in PEM Water Electrolyzer.

Achieving robust long-term durability with high catalytic activity at low iridium loading remains one of great challenges for proton exchange membrane water electrolyzer (PEMWE). Herein, we report the low-temperature synthesis of iridium oxide foam platelets comprising edge-sharing IrO6 octahedral honeycomb framework, and demonstrate the structural advantages of this material for multilevel tuning of anodic catalyst layer across atomic-to-microscopic scales for PEMWE. The integration of IrO6 octahedral honeycomb framework, foam-like texture and platelet morphology into a single material system assures the generation and exposure of highly active and stable iridium catalytic sites for the oxygen evolution reaction (OER), while facilitating the reduction of both mass transport loss and electronic resistance of catalyst layer. As a proof of concept, the membrane electrode assembly in single-cell PEMWE based on honeycomb-structured IrOx foam platelets, with a low iridium loading (~0.3 mgIr/cm2), is demonstrated to exhibit high catalytic activity at ampere-level current densities and to remain stable for more than 2000 hours.

DNA-Mediated Au-Au Dimer-Based Surface Plasmon Coupling Electrochemiluminescence Sensor for BRCA1 Gene Detection.

Herein, we constructed a DNA-mediated Au-Au dimer-based surface plasmon coupling electrochemiluminescence (SPC-ECL) sensor. In the SPC-ECL sensing system, graphite phase carbon nitride quantum dots (GCN QDs) worked as an ECL emitter. A DNA rigid chain structure was employed to connect two Au NPs in an equilateral triangle configuration to form the Au-Au dimers. Due to the hot spot effect, the designed Au-Au dimers had a strong electromagnetic field intensity, which can greatly enhance the ECL signal of GCN QDs than a single Au nanoparticle. The gap distance of dimers can be effectively regulated by the DNA length, which resulted in different electromagnetic field intensities. Therefore, the different SPC-ECL amplification effects on the GCN QD signal by Au-Au dimers have been revealed. The maximum ECL signal of GCN QDs can be enhanced fourfold based on the Au-Au dimers with a gap distance of 2 nm. Furthermore, the biosensor showed good analytical performance for the detection of breast cancer susceptibility gene 1 (BRCA1 genes) (1 fM-1 nM) with a detection limit of 0.83 fM. This work provided an effective and precise SPC-ECL sensing mode for the diagnosis and prognosis of breast cancer.

Polarization-Resolved Electrochemiluminescence Sensor Based on the Surface Plasmon Coupling Effect of a Au Nanotriangle-Patterned Structure.

This work focused on the construction of a nanomaterial-patterned structure for high-resolved ECL signal modulation. Due to the surface coupling effect, the different shapes and distribution states of surface plasmonic nanomaterials not only affect the luminescence intensity enhancement but also decide the electrochemiluminescence (ECL) polarization characteristics. Herein, tin disulfide quantum dots were synthesized via a solvothermal method as ECL emitters. Compared with other nanostructures, Au nanotriangle (Au NT) displayed both the localized surface plasmon resonance electromagnetic enhancement effect and the tip amplification effect, which had significant hot spot regions at three sharp tips. Therefore, self-assembled Au NT-based patterned structures with high density and uniform hot spots were constructed as ideal surface plasmonic materials. More importantly, the distribution states of the hot spots affect the polarization characteristics of ECL, resulting in directional ECL emission at different angles. As a result, a polarization-resolved ECL biosensor was designed to detect miRNA 221. Moreover, this polarization-resolved biosensor achieved good quantitative detection in the linear range of 1 fM to 1 nM and showed satisfactory results in the analysis of the triple-negative breast cancer patients' serum.

Ni(OH)2 derived Ni-MOF supported on carbon nanowalls for supercapacitors.

Metal organic frameworks (MOFs) are expected to be promising pseudocapacitve materials because of their potential redox sites and porous structures. Nevertheless, the conductivity inferiority of MOF strongly decreases their structural advantages, therefore resulting in unsatisfying electrochemical performance. Herein, we propose an efficient strategy to enhance conductivity and thus electrochemical properties, in Ni(OH)2 is electrochemically deposited on carbon nanowalls as the precursor for oriented MOF. The synthesized vertically oriented MOF sheets show an almost triple high capacitance of 677 F g-1 than MOF powder of 239 F g-1 at the current density of 2 A g-1. Correspondingly, an asymmetric supercapacitor is fabricated, which can deliver a maximum energy density of 20.7 Wh kg-1 and a maximum power density of 23 200 W kg-1. These promising results indicate that modulating the conductivity of MOF is the key step to pursuit upgrading electrochemical performance.

Unlocking the potential of metal organic frameworks for synergized specific and areal capacitances via orientation regulation.

Metal organic frameworks (MOFs) with numerous potential pseudocapacitive sites are quite appealing to supercapacitors with high specific and areal capacitances. However, MOFs suffer from a low conductivity nature, resulting in a mediocre electrochemical performance. Herein, we propose a template-growth strategy of MOF to enhance both specific and areal capacitances of MOF as the electrode material for supercapacitor. As the loading mass of MOF increases from 2 to 5 mg, the specific capacitance also increases from 937 to 2387 Fg-1 (431 to 1098 Cg-1) and areal capacitance 1.87 to 11.94 Fcm-2 (0.86 to 5.49 Ccm-1). Accordingly, a hybrid MOF//AC supercapacitor can deliver a maximum energy density of 67 Wh kg-1 and a maximum power density of 6000 W kg-1. These results point to a way to fabricate MOF electrode of supercapacitor with high specific and areal capacitance, which leads them to a more practical future.

Carbon intermediate boosted Fe-ZIF derived α-Fe2O3 as a high-performance negative electrode for supercapacitors.

Earth-abundant Fe2O3 is a promising material for the negative electrode of supercapacitors by virtue of its wide potential windows. However, the unsatisfactory electrical conductivity and poor ionic diffusion rate within Fe2O3 results in degraded electrochemical performance. In this work, to address these issues, we demonstrate an easy method to synthesize Fe-based zeolitic imidazolate framework (Fe-ZIF) derived α-Fe2O3@C with remarkable supercapacitive properties. The as-obtained α-Fe2O3@C electrode, with the particular benefit of dispersed distribution of carbon, enabling fast electrochemical response, presents a prospective specific capacitance of 161 Fg-1 at a current density of 1 Ag-1. Furthermore, by using the α-Fe2O3@C architecture as the negative electrode, we fabricated a supercapacitor with Na0.5MnO2 as the positive electrode. Our supercapacitor shows a high energy density of 25 Whkg-1, while the corresponding power density is 2400 Wkg-1 at a current density of 2 Ag-1.

N-doped carbon anchored CoS2/MoS2 nanosheets as efficient electrocatalysts for overall water splitting.

The oriented two-dimensional porous nitrogen-doped carbon embedded with CoS2 and MoS2 nanosheets is a highly efficient bifunctional electrocatalyst. The hierarchical structure ensures fast mass transfer capacity in improving the electrocatalytic activity. And the greatly increased specific surface area is beneficial to expose more electrocatalytically active atoms. For oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) tests in 1 mol/L KOH solution, only 194 and 140 mV overpotential are required to achieve a current density of 10 mA/cm2, respectively. Our research provides an effective strategy for synergizing the individual components in nanostructures for a wide range of electrocatalytic reactions.

In-plane Assembly of Distinctive 2D MOFs with Optimum Supercapacitive Performance.

2D metal organic frameworks (MOFs) with layered structure and much exposed atoms on the surface are expected to be promising electrode materials for hybrid supercapacitors. However, the insulating character strongly hinders their further applications. Herein, we propose a novel MOF//MOF strategy to enhance 2D MOF's conductivity, by which two kinds of 2D MOFs with specific functions are concurrently incorporated into one homogeneous layered MOF with enhanced conductivity and electrochemical performance. The synthesized Ni//Cu MOF shows a triple high capacitance of 1,424 Fg-1 and excellent rate capability compared with the pristine Ni MOF. A hybrid supercapacitor is thereof fabricated, which can provide a maximum energy density of 57 Wh kg-1 and a maximum power density of 48,000 W kg-1. These results not only demonstrate that our strategy can effectively boost the conductivity and redox activity but also pave new routes to synthesize new MOFs for various applications.