Rechargeable Aqueous Aluminum Organic Batteries.

Aqueous aluminum-ion batteries (AABs) are regarded as promising next-generation energy storage devices, and the current reported cathodes for AABs mainly focused on inorganic materials which usually implement a typical Al3+ ions (de)insertion mechanism. However, the strong electrostatic forces between Al3+ and the host materials usually lead to sluggish kinetics, poor reversibility and inferior cycling stability. Herein, we employ an organic compound with redox-active moieties, phenazine (PZ), as the cathode material in AABs. Different from conventional inorganic materials confined by limited lattice spacing and rigid structure, the flexible organic molecules allow a large-size Al-complex co-intercalation through reversible redox active centers (-C=N-) of PZ. This co-intercalation behavior can effectively reduce desolvation penalty, and substantially lower the Coulombic repulsion during the ion (de)insertion process. Consequently, this organic cathode exhibits a high capacity and excellent cyclability, which exceeds those of most reported electrode materials for AABs. This work highlights the anion co-intercalation chemistry of redox-active organic materials, which is expected to boost the development of high-performance multivalent-ion battery systems.

Flexible SERS platform based on Ti3C2Tx-modified filter paper: preparation and SERS application.

A novel, simple, and inexpensive flexible surface-enhanced Raman-scattering (SERS) platform based on common laboratory filter paper modified with Ti3C2Tx flakes was reported. Ti3C2Tx synthesized from a Ti3AlC2 phase with a mixture of HCl and LiF and Ti3C2Tx nanosheets were characterized by the TEM, XRD, UV-Vis spectrum, and Raman spectrum. Paper-based substrate has been proven to sample on rough and irregular surfaces. Thus, Ti3C2Tx was further manufactured as paper substrate by the immersion method to transfer nanosheets to filter paper. SERS activity of prepared substrate was demonstrated using R6G by the same filter paper modified with and without Ti3C2Tx, and various concentrations of R6G were tested to prove the sensitivity of the substrates. Further detection of CV and MG certified the universality of paper substrate based on Ti3C2Tx nanosheets for detection of organic pollutants. The uniformity and stability were proved by CV and R6G molecules. This SERS platform combines the advantages of 2D material and flexible paper scaffolds, resulting in a highly sensitive, cost-efficient, and easy-to-manufacture large-scale flexible substrate and is expected to be used in practice.

Large-scale two-dimensional titanium carbide MXene as SERS-active substrate for reliable and sensitive detection of organic pollutants.

As a new class of two-dimensional material, MXene not only has the unique planar structure, electronic and optical properties, but also has a large surface area and hydrophilicity, which make them to build as potential SERS substrates with good sensitivity and stability. In this work, we reported a modified method by adjusting the ratio of HCl to LiF and reducing sonicate time to form large-sized monolayer Ti3C2Tx nanosheets. SERS performance of Ti3C2Tx was demonstrated by detecting dye molecules such as CV, R6G and MG. A remarkable enhanced effect was obtained, and Raman signals up to 10-8 M could be detected. Furthermore, the relationship between SERS effects and illumination laser wavelengths of different probe molecules has been studied, the results showed the selectivity between dye molecules and the excitation wavelengths. Besides, the uniformity and stability of the substrates have been proved by mapping experiments in a large area (80 × 80 µm2). The results demonstrated that Ti3C2Tx nanosheets can be built as lager-sized, uniform and stable sensor for ultra-sensitive detection of organic dye pollutant molecules.