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.

The corrosion inhibition performance of a quaternary phosphonium-based ionic liquid, i.e., hexadecyltriphenylphosphonium bromide (HPP), on mild steel in 1 M HCl solution was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. The surface characterization of mild steel was examined by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The results revealed that the inhibition efficiency increases with its increasing concentration, and it can reach up to 99.1% at the concentration of 0.07 mM HPP. PDP data showed that the absorption of HPP conformed to Langmuir adsorption, which served as a mixed-type inhibitor, involving chemisorption and physisorption. SEM analysis confirmed the formation of barrier film on the metal surface, inhibiting the acid attack. Moreover, density functional theory (DFT) calculations and molecular dynamics (MD) simulations were conducted to elucidate the adsorption mechanism of inhibitor molecules on the mild steel surface. A match between the experimental and theoretical findings was evidenced.

Generally, MoS₂ is easily oxidized when exposed to oxygen, and the antioxidation mechanism of MoS₂ is still a challenge. Thus, more efforts were made to greatly improve its antioxidation performance. It was reported that the Ti atom doped with MoS₂ was treated as the effective method to enhance its antioxidation performance; however, the detailed antioxidation mechanism was not well understood. Superior to experimental methods, the first-principles method could provide deep insight into the atomic information and serve as a useful tool to gain an understanding of the antioxidation mechanisms of the doped MoS₂; thus, the antioxidation behavior of the Ti-doped MoS₂ was investigated in detail using first-principles calculations. However, an opposing conclusion was obtained from the calculated results compared to the previous experimental results; that is, the incorporation of the Ti atom was not helpful for improving the antioxidation performance of MoS_2. The strange phenomenon was well probed and discussed in detail, and understanding the oxidation mechanism of the Ti-doped MoS₂ would be helpful for expanding its applications in the ambient atmosphere.