Self-assembly of an amino acid derivative as an anode interface layer for advanced alkaline Al-air batteries.

Alkaline Al-air batteries (AABs) are gaining increasing attention for large-scale energy storage systems due to their attractive intrinsic safety and cost-effectiveness. Nonetheless, the future development of AABs is substantially hampered by water-induced self-corrosion processes on the Al anode. In this work, we introduce an amino acid derivative, namely Nα-Boc-N1-formyl-L-tryptophan (NBLT), into a 4 M NaOH electrolyte to construct a unique layer that can effectively regulate the surface microstructure of the Al anode. The findings of the experiments show that NBLT can be used as a reliable corrosion inhibitor. The effectiveness of such inhibitors increases with NBLT concentration, reaching a maximum of 73.9% at 1.5 mM. In comparison to the pristine condition, there is a significant increase in anode utilization from 31.8% to 82.9%, capacity density from 947.9 to 2469.1 mA h g-1, and energy density from 1261.6 to 3384.6 W h kg-1. Theoretical calculations indicate that the carboxyl moieties present in the NBLT molecule establish coordination bonds with the Al atoms, thereby exerting a dominant role in the formation of the self-assembled barrier. The present investigation paves an effective strategy to inhibit reactions between anodes and electrolytes for advanced AABs.

On the antibacterial photodynamic inactivation mechanism of Emodin and Dermocybin natural photosensitizers: A theoretical investigation.

A DFT and TDDFT study has been carried out on monomeric anthraquinones Emodin and Dermocybin (Em, Derm) recently proposed as natural antibacterial photosensitizers able to act also against gram-negative microbes. The computational study has been performed considering the relative amount of neutral and ionic forms of each compound in water, with the variation of pH. The occurrence of both Type I and Type II photoreactions has been explored computing the absorption properties of each species, the spin-orbit coupling constants (SOC), the vertical ionization potentials and the vertical electron affinities. The most plausible deactivation channels leading to the population of excited triplet states have been proposed. Our data indicate Emodin as more active than Dermocybin in antimicrobial photodynamic therapy throughout the Type II mechanism. Our data support a dual TypeI/II activity of the monomeric anthraquinones Emodin and Dermccybin in water, in all the considered protonation states.

Effect of Indole-2-carboxylic Acid on the Self-Corrosion and Discharge Activity of Aluminum Alloy Anode in Alkaline Al-Air Battery.

Al-air battery has been regarded as a promising new energy source. However, the self-corrosion of aluminum anode leads to a loss of battery capacity and a decrease in battery longevity, limiting its commercial applications. Herein, indole-2-carboxylic acid (ICA) has been added to 4 M NaOH as a corrosion inhibitor. Its impact on the self-corrosion of aluminum alloy and the enhancement of the functionality of Al-air batteries at various concentrations have been investigated. X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques have been used to examine the compositional and morphological alterations of aluminum alloy surfaces. Electrochemical and hydrogen evolution tests showed that indole-2-carboxylic acid is an efficient corrosion inhibitor in alkaline solutions, and its impact grows with concentration. Our findings demonstrated that when the inhibitor concentration is 0.07 M, the inhibition efficiency is 54.0%, the anode utilization rises from 40.2% to 79.9%, the capacity density increases from 1197.6 to 2380.9 mAh g-1, and the energy density increases from 1469.9 to 2951.8 Wh kg-1. In addition, theoretical calculations have been performed to support the experimental results.