Polycyclic Aromatic Hydrocarbons as a New Class of Promising Cathode Materials for Aluminum-Ion Batteries.

As an emerging post-lithium battery technology, aluminum ion batteries (AIBs) have the advantages of large Al reserves and high safety, and have great potential to be applied to power grid energy storage. But current graphite cathode materials are limited in charge storage capacity due to the formation of stage-4 graphite-intercalated compounds (GICs) in the fully charged state. Herein, we propose a new type of cathode materials for AIBs, namely polycyclic aromatic hydrocarbons (PAHs), which resemble graphite in terms of the large conjugated π bond, but do not form GICs in the charge process. Quantum chemistry calculations show that PAHs can bind AlCl4 - through the interaction between the conjugated π bond in the PAHs and AlCl4 - , forming on-plane interactions. The theoretical specific capacity of PAHs is negatively correlated with the number of benzene rings in the PAHs. Then, under the guidance of theoretical calculations, anthracene, a three-ring PAH, was evaluated as a cathode material for AIBs. Electrochemical measurements show that anthracene has a high specific capacity of 157 mAh g-1 (at 100 mA g-1 ) and still maintains a specific capacity of 130 mAh g-1 after 800 cycles. This work provides a feasible "theory guides practice" research model for the development of energy storage materials, and also provides a new class of promising cathode materials for AIBs.

In Situ Growth of Three-Dimensional Graphene Films for Signal-On Electrochemical Biosensing of Various Analytes.

In this work, an in situ growth protocol is introduced to fabricate three-dimensional graphene films (3D GFs) on gold substrates, which are successfully utilized as working electrode for electrochemical detection of nucleic acid (microRNA) and protein (lysozyme) based on a signal-on sensing mechanism. To realize the bridge between the gold substrate and graphene film, a monolayer of 4-aminothiophenol is self-assembled on the substrate, which is then served as connectors for the growth of 3D GFs on the gold substrate by the hydrothermal reduction (HR) technique. Moreover, given the excellent properties, such as enlarged surface area, strong binding strength between 3D GFs and gold substrate, and improved conductivity, the proposed 3D GF-fabricated gold substrate is readily employed to the construction of electrochemical biosensing platforms through introduction of magnetic nanoparticles (MNPs) as probe carriers. On the basis of the strand displacement reaction and specific binding between aptamer and its target, the developed biosensors achieve signal-on detection of microRNA-155 (miR-155) and lysozyme (Lyz) with high sensitivity and selectivity and further successfully applied to human serum assay. Overall, the proposed strategy for in situ growth of 3D GFs provides a powerful tool for a wide range of applications, which is not limited to electrochemical biosensors and can be extended to other areas, such as electrocatalysis and electronic energy-related systems.

ß-Hydrogen of Polythiophene Induced Aluminum Ion Storage for High-Performance Al-Polythiophene Batteries.

The urgent need for large-scale, low-cost energy storage has driven a new wave of research focusing on innovative batteries. Due to the high capacity and the low-cost of elemental Al, aluminum-ion batteries (AIBs) are expected as promising candidates for future energy storage. However, further development of AIBs is restricted by the performance of existing carbon-based cathodes and metal chalcogenide cathode materials. In this work, we deposited polythiophene (Pth) on a graphene oxide (Pth@GO) composite and used it as an AIB cathode material. This Pth@GO composite possesses high exposure of Pth active sites, high conductivity, and high structure stability while providing a very high discharge capacity (up to 130 mAh g-1) and outstanding cyclic stability (maintaining above 100 mAh g-1 after 4000 cycles). First principles calculations and experimental results show that the charge is stored on Pth@GO through an electrostatic attraction between AlCl4- and ß-hydrogen (Cß-H) sites in polythiophene.