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Use of aluminum alloy anodes as metal fuel in electrochemical batteries has specific advantages in numerous applications. In this paper, we report novel Al alloy anodes obtained by adding In and Bi to a reported Al ternary-element alloy, Al-Zn-Sn. An electron probe microanalyzer is used to obtain the elemental composition of Al-5Zn-0.1Sn, Al-5Z-0.1Sn-0.1In, and Al-5Zn-0.1Sn-0.1In-0.1Bi. Tafel analysis, electrochemical impedance spectroscopy, and constant-current chronopotentiometry are performed for electrochemical analysis. In addition, the self-corrosion of the alloys is examined to determine the hydrogen evolution and anode discharge stability. These results indicate that Al-5Zn-0.1Sn-0.1In-0.1Bi has the highest anode performance. On the basis of the scanning electron microscopy and transmission electron microscopy microstructure analysis, we propose that the dissolution and sedimentation process induced by Bi nanoprecipitates may activate a passive Al surface, significantly enhancing the discharge efficiency. • Al-5Zn-0.1Sn-0.1In-0.1Bi alloy is first synthesized which displays high discharging performance in battery applications. • XRD, SEM, and TEM showed the minor crystals and grains in Al-5Zn-0.1Sn-0.1In-0.1Bi. • The self-corrosion is examined indicating a dissolution mechanism of the Al alloy. • In and Bi in the Al alloy collapsed during discharge, which refreshed the passivated Al surface. [ABSTRACT FROM AUTHOR]

• B2 phases in Al 0.3 CoCrFeNi HEAs are purposely controlled by annealing treatment. • Effect of B2 phases on corrosion resistance of Al 0.3 CoCrFeNi HEAs is studied. • The B2 phases deteriorate the pitting corrosion resistance of Al 0.3 CoCrFeNi HEAs. • B2 phases act as preferential pit nucleation sites and facilitate pit propagation. The corrosion resistance of Al-Co-Cr-Fe-Ni high entropy alloys (HEAs) is probably affected by B2 phases. In this paper, the effect of B2 phases on the corrosion behavior of Al 0.3 CoCrFeNi HEAs in 3.5 wt% NaCl solution is clarified in this paper by purposely controlling the formation of B2 phases using annealing treatment. The microstructure characterization reveals that the content of (Al, Ni)-rich and Cr-poor B2 phases increases and the electrochemical measurements show that the pitting corrosion resistance is deteriorated as the annealing temperature decreases. Accordingly, the B2 phase is confirmed to be detrimental to the corrosion resistance of Al 0.3 CoCrFeNi HEAs. It can be attributed to the preferential dissolution of B2 phases causing easier pit initiation, which is evidenced by the corrosion morphology observation and scanning Kelvin probe force microscopy measurements, and to the slower repassivation rate leading to easier pit propagation, as demonstrated by the quantitative analysis of potentiostatic polarization curves. [ABSTRACT FROM AUTHOR]

As one of the most efficient, low-cost, and readily available electrocatalysts for oxygen evolution reaction (OER) in alkaline environments, the nickel-iron electrocatalyst is of great significance to commercial water splitting. In this study, NiFe-layered double hydroxide loaded on nickel foam (NiFe-LDH/NF) was synthesized via a simple one-step hydrothermal method, whose OER catalytic performance could be successfully optimized by further electrochemical reconstruction. The results show that NF is an effective precursor to loading crystallized Ni(OH) 2 nanoparticles during hydrothermal synthesis, leading to the generation of high-performance NiOOH during OER reconstruction. Under the optimal Ni:Fe feeding ratio, Ni 2 Fe 1 -LDH/NF requires an ultra-low OER overpotential of 239 mV at 50 mA cm−2 and 260 mV at 100 mA cm−2, whose Tafel slope is only 64.1 mV dec−1. Impressively, Ni 2 Fe 1 -LDH/NF also achieves an ultra-low voltage of 1.44 V at 10 mA cm−2 with excellent long-term stability for overall water splitting. Unlike the previous viewpoint that only Ni species dominate surface reconstruction of NiFe-LDH, in this article the decisive influence related to Fe species on the reconstruction layers' activity and stability is confirmed by electrochemistry, Raman, and XPS analysis during reconstruction process. During OER reconstruction, the surface Ni:Fe ratios can be "self-adaptively" regulated to an appropriate region, thus the stable reconstruction layers rich in NiOOH can be formed as the protective shells for NiFe-LDH. Furthermore, such "self-adaptive" reconstruction, assisted with appropriate initial Ni:Fe feeding ratios, can also stimulate more Ni3+ active sites for OER, benefitting the outstanding catalytic performance of NiFe-LDH/NF for overall water splitting and prospective large-scale application. [Display omitted] • There are some highlights in this paper may be found interested by the general readers. • Unstable iron-rich phases start self-adaptively electrochemical reconstruction. • Self-adaptive reconstruction promotes the OER catalytic activity and stability. • The optimal electrocatalyst exhibits 260 mV overpotential at 100 mA·cm−2 for OER. • The electrocatalyst only needs 1.44 V at 10 mA·cm−2 for overall water splitting. [ABSTRACT FROM AUTHOR]

Hydrogen production from electrochemical water dissociation has been considered as a facile and promising approach to address energy related crisis in the world. In this regard, development of high performance, stable, and cost-effective catalysts for full water splitting is highly demanded. In this work a high performance electrocatalyst based on commercially available Tin oxide nanoparticles mixed with carbon nanotubes (CNT) is presented for electrocatalytic water splitting. The catalyst prepared through facile dropped casting method and obtained a high electrocatalytic activity for full water splitting. One of the key important parameters in water splitting is producing hydrogen/oxygen at high rate under long term stability. This is problematic because it would result in catalyst degradation and performance fallen. However, herein, the prepared electrocatalyst demonstrated a high stability of more than 10 h operation under a high applied current density of 100 mA.cm−2 for hydrogen evolution reaction. For the both hydrogen and oxygen, the prepared catalyst (SnO 2 /CNT coated on carbon paper) delivered the current density of 10 mA.cm−2 at a low overpotentials of 150 mV and 250 mV, respectively. Our observations validate the excellent capability in significantly modifying the catalytic activity of transition metal compound catalysts with carbon nanostructures. [Display omitted] • A synergetic effect of CNT and SnO 2 combination on the electrocatalytic performance was observed. • A lower overpotentials required to reach high current densities, along with high stability at high current. • CNT hybridization with SnO 2 influenced the Volmer step of HER. Also, the adsorption of oxygen and hydrogen affected. • The open structure accelerated the gas detachments during OER or HER, influencing the performance of the system. [ABSTRACT FROM AUTHOR]