Double transition metal-containing M₂TiAlC₂ <i>o</i>-MAX phases as Li-ion batteries anodes: a theoretical screening

Here, thermodynamic stability and lithium storage properties of double transition metal M2TiAlC2 o-MAX phases (M = Cr, V, Mo, Nb, Ta, Hf, Zr, Sc, Y, La) are theoretically investigated by density functional theory (DFT) calculation. M2TiAlC2 with a larger M atomic radius shows larger interlayer space that may benefit the Li-ion intercalation. A promising theoretical capacity of 276.87 mAh g-1 is predicted for Sc2TiAlC2. The low Li-ion diffusion barriers (0.57–0.64 eV) for M2TiAlC2 indicate the possibility to achieve fast Li-ion diffusion that is crucial for designing high-power batteries. This work provides opportunities to explore MAX phases as promising Li-ion storage materials. This work investigates the thermostability and lithium storage properties of double transition metal o-MAX phases by DFT calculation and provides a guideline for exploring MAX phases for lithium storage applications.</p

Molten salt derived Mo₂AlB₂ with excellent HER catalytic performance

Mo2AlB2 is a lamellar transition metal boride that is prepared by selectively etching the MoAlB MAB phase precursor. Most methods for synthesizing Mo2AlB2 require the use of strong acids or bases and a long reaction time. In this study, we present a Lewis acid molten salt method for synthesizing the lamellar structured Mo2AlB2 by selectively etching a layer of aluminium atoms from the MoAlB precursor. The synthesized Mo2AlB2 shows excellent catalytic activity for hydrogen evolution reaction under alkaline conditions, with long-term stability, and a low overpotential of 145 mV and Tafel slope of 76 mV dec−1 at 10 mA cm−2. Mo2AlB2 was synthesized through a novel molten salt method of etching MoAlB, resulting in exceptional HER catalytic performance in alkaline conditions.</p

Additional file 1 of Biochemical and molecular characterization of a novel glycerol dehydratase from Klebsiella pneumoniae 2e with high tolerance against crude glycerol impurities

Additional file 1: Table S1. Primers used for PCR in this study

Photoirradiation-Induced Capacitance Enhancement in the <i>h</i>‑WO₃/Bi₂WO₆ Submicron Rod Heterostructure under Simulated Solar Illumination and Its Postillumination Capacitance Enhancement Retainment from a Photocatalytic Memory Effect

Recently, photoassisted charging has been demonstrated as a green and sustainable approach to successfully enhance the capacitance of supercapacitors with low cost and good efficiency. However, their light-induced capacitance enhancement is relatively low and is lost quickly when the illumination is off. In this work, a novel active material system is developed for supercapacitors with the photoassisted charging capability by the decoration of a small amount of Bi2WO6 nanoparticles on an h-WO3 submicron rod surface in situ, which forms a typical type II band alignment heterostructure with a close contact interface through the co-sharing of W atoms between h-WO3 submicron rods and Bi2WO6 nanoparticles. The photogenerated charge carrier separation and transfer are largely enhanced in the h-WO3/Bi2WO6 submicron rod electrode, which subsequently allows more charge carriers to participate in its photoassisted charging process to largely enhance its capacitance improvement under simulated solar illumination than that of the h-WO3 submicron rod electrode. Furthermore, the h-WO3/Bi2WO6 submicron rod electrode could retain its photoinduced capacitance enhancement in the dark for an extended period of time from the photocatalytic memory effect. Thus, our work provides a solution to the two major drawbacks of reported supercapacitors with the light-induced capacitance enhancement property, and supercapacitors based on active materials with the photocatalytic memory effect could be utilized in various technical fields

Activating Pseudocapacitive Charge Storage of Molten-Salt-Synthesized MXenes in Mild Aqueous Electrolytes

Traditional MXenes, synthesized by an HF-based wet chemical process, are promising pseudocapacitive materials in strong acidic aqueous electrolytes, but they show poor performance in neutral or alkaline aqueous electrolytes due to the lack of pseudocapacitive activity. In this work, we demonstrate that molten-salt-synthesized MXenes (MS-MXenes) with −O and −Cl surface groups can exhibit a high pseudocapacitive behavior in both AlCl3 and acetate-buffered aqueous electrolytes. MS-Ti2CTx MXene achieves a high specific capacitance of 318 C g–1 in a 1 M AlCl3 electrolyte and 280 C g–1 in a 1 M acetate buffer electrolyte. Furthermore, the mild acidity of AlCl3 and acetate electrolytes suppresses hydrogen evolution and enables more negative cutoff potentials of −1.6 and −1.4 V versus Hg/Hg2SO4, respectively. Most of the charge storage and release occur at potentials below −1 V versus Hg/Hg2SO4, making MS-MXene carbides suitable for negative electrodes. By pairing with a MnO2 positive electrode, the asymmetric supercapacitor delivers a high voltage of 2.1 V and an energy density of 37 Wh kg–1 together with high cycling stability in a 1 M acetate aqueous electrolyte. Our findings demonstrate the potential of MXenes as negative electrode materials in mild aqueous electrolytes, opening avenues for their practical implementation in advanced energy storage devices