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3D hollow reduced graphene oxide foam as a stable host for high-capacity lithium metal anodes
Pengcheng Yao, Qiyuan Chen, Yu Mu, Jie Liang, Xiuqiang Li, Xin Liu, Yang Wang, Bin Zhu and Jia Zhu
Mater. Chem. Front., 2019,3, 339-343
http://dx.doi.org/10.1039/C8QM00499D

Lithium is considered to be a promising anode material for high-energy batteries on account of its high capacity and low potential. However, both dendritic lithium formation and very large volume changes during cycling severely restrict its practical applications. Herein, we propose a 3D hollow reduced graphene oxide foam as a host for prestoring lithium. Aside from the advantages of accommodating volume change and lowering the local current density, this unique structure also provides a large host space, one that enables lithium prestorage both outside and inside the reduced graphene oxide, in which Li occupies ∼85 weight percent of the whole composite electrode. The anode showed a corresponding gravimetric specific capacity as high as 3280 mA h g⁻¹. Moreover, it showed highly stable cycling with small hysteresis at 1 mA cm⁻² in the carbonate electrolyte. When it was assembled into a full cell with NCM (Li(Ni_1/3Co_1/3Mn_1/3)O₂) as the cathode, the resulting battery showed good cycling performance, having displayed 92% capacity retention (128.2 mA h g⁻¹) and appealing power capacity (82 mA h g⁻¹ at 5C) after being cycled 200 times at 0.3C.

Development and reactive oxygen-species scavenging activity of a new chemical hydrogen-generating system, CaMg₂-hydroxypropyl cellulose-citric acid, prepared using Laves-phase CaMg₂ and its relationship to chemical hardness

Shigeki Kobayashi, Kazuyoshi Chiba and Takashi Tomie
Mater. Chem. Front., 2019, Advance Article
http://dx.doi.org/10.1039/C8QM00488A

We developed a new chemical hydrogen-generating CaMg₂-hydroxypropyl cellulose-citric acid (CAMGCC) system from Laves-phase CaMg₂ by using an arc melting method. The CAMGCC generated hydrogen gas (H₂) rapidly for 2–3 min on the addition of water. Moreover, the CAMGCC system could scavenge reactive oxygen species (ROS), such as toxic hydroxyl radicals (˙OH) and superoxides (O₂⁻˙) effectively. To develop a new chemical hydrogen-generating system that generates H₂ efficiently, it is essential to calculate the quantity (ΔQ) of electron transfer from metal and alloy to H₂O by using the absolute hardness (η) and absolute electronegativity (χ) based on chemical hardness. Metals and alloys with a large amount of calculated ΔQ can be used as excellent materials to develop a chemical hydrogen-generating system. A larger ΔQ of electron transfer from the metal to H₂O results in a greater antioxidant activity of the system. The results were supported by using the calculation results for clusters of CaMg₂ and Mg₃, instead of crystalline CaMg₂ and Mg. These studies are important in the development of chemical hydrogen-generating systems and antioxidants.

Luminescent solar concentrators: boosted optical efficiency by polymer dielectric mirrors
G. Iasilli, R. Francischello, P. Lova, S. Silvano, A. Surace, G. Pesce, M. Alloisio, M. Patrini, M. Shimizu, D. Comoretto and A. Pucci
Mater. Chem. Front., 2019, Advance Article
http://dx.doi.org/10.1039/C8QM00595H

We report on the optical efficiency enhancement of luminescent solar concentrators based on a push–pull fluorophore realized using high dielectric contrast polymer distributed Bragg reflectors as back mirrors. The Bragg stacks are obtained by alternating layers of cellulose acetate and thin films of a new stable and solution processable hydrated titania–poly(vinyl alcohol) nanocomposite (HyTiPVA) with a refractive index greater than 1.9 over a broad spectral range. The results obtained with these systems are compared with enhancements provided by standard Bragg reflectors made of commercial polymers. We demonstrate that the application of the Bragg stacks with photonic band-gap tuned to the low energy side of the dye emission spectrum induces a 10% enhancement of optical efficiency. This enhancement is the result of a photon recycling mechanism and is retained even in a scaled-up device where the Bragg mirrors are used in a mosaic configuration.

Hypersonic poration of supported lipid bilayers
Yao Lu, Jurriaan Huskens, Wei Pang and Xuexin Duan
Mater. Chem. Front., 2019, Advance Article
http://dx.doi.org/10.1039/C8QM00589C

Hypersound (ultrasound of gigahertz (GHz) frequency) has been recently introduced as a new type of membrane-disruption method for cells, vesicles and supported lipid bilayers (SLBs), with the potential to improve the efficiency of drug and gene delivery for biomedical applications. Here, we fabricated an integrated microchip, composed of a nano-electromechanical system (NEMS) resonator and a gold electrode as the extended gate of a field effect transistor (EGFET), to study the effects of hypersonic poration on an SLB in real time. The current recordings revealed that hypersound enabled ion conduction through the SLB by inducing transient nanopores in the membrane, which act as the equivalent of ion channels and show gating behavior. The mechanism of pore formation was studied by cyclic voltammetry (CV), atomic force microscopy (AFM) and laser scanning microscopy (LSM), which support the causality between hypersound-triggered deformation and the reversible membrane disruption of the SLB. This finding contributes to the development of an approach to reversibly control membrane permeability by hypersound.

Highly-efficient semi-transparent organic solar cells utilising non-fullerene acceptors with optimised multilayer MoO₃/Ag/MoO₃ electrodes

Guangjun Sun, Munazza Shahid, Zhuping Fei, Shenda Xu, Flurin D. Eisner, Thomas D. Anthopolous, Martyn A. McLachlan and Martin Heeney
Mater. Chem. Front., 2019, Advance Article
http://dx.doi.org/10.1039/C8QM00610E

We report the optimisation of a semi-transparent solar cell based on a blend of a recently reported high performance donor polymer (PFBDB-T) with a non-fullerene acceptor derivative (C8-ITIC). The performance is shown to strongly depend on the nature of the semi-transparent electrode, and we report the optimal fabrication conditions for a multilayer MoO₃/Ag/MoO₃ electrode. The effect of deposition rate and layer thickness of both the Ag and the outer MoO₃ on transparency and sheet resistance is investigated, and is shown to have a significant impact on the overall device performance. The optimised PFBDB-T:C8-ITIC based devices exhibit an average power conversion efficiency (PCE) of 9.2% with an average visible transmittance (AVT) of 22%.

Alkoxythiophene and alkylthiothiophene π-bridges enhance the performance of A–D–A electron acceptors
Lei Zhang, Ke Jin, Zuo Xiao, Xingzhu Wang, Tao Wang, Chenyi Yi and Liming Ding
Mater. Chem. Front., 2019, Advance Article
http://dx.doi.org/10.1039/C8QM00647D

Three nonfullerene acceptors CO5DFIC, CO5DFIC-OT and CO5DFIC-ST were developed. CO5DFIC-OT and CO5DFIC-ST have alkoxythiophene and alkylthiothiophene π-bridges, respectively, and they show higher LUMO levels and enhanced light-harvesting capability compared to CO5DFIC without π-bridges. CO5DFIC-OT and CO5DFIC-ST solar cells gave higher open-circuit voltage, short-circuit current density and power conversion efficiency than CO5DFIC cells.