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Batteries with manganese (di)oxide/zinc chemistry and aqueous-based electrolytes have the potential to address energy storage demands of stationary applications primarily because of the abundant availability of Zn and Mn-oxides, their intrinsic low cost, and the high specific/volumetric charge capacities. Herein, we report the use of Mn 3 O 4 (hausmannite phase of manganese oxide) as the positive electrode material in a rechargeable near-neutral Mn-oxide/Zn battery configuration. Electrochemical investigations reveal that the hausmannite phase can activate for charge/discharge processes during the first 40 to 50 cycles and then a maximum capacity is obtained. This material shows excellent reversibility (~800 cycles) in keeping more than 65% of its maximum capacity. For the first time, the hausmannite activation mechanism was better understood under near-neutral conditions. By using different characterization techniques (X-ray powder diffraction [XRD], inductively coupled plasmaoptical emission spectrometry [ICP-OES], X-ray photoelectron spectroscopy [XPS], and energy dispersive X-ray spectroscopy [EDS]) formation of Zn-based compounds at the electrode surface was confirmed. One of the compounds formed is the layered double hydroxide (Zn 4 SO 4 [OH] 6 Á 5H 2 O) that forms as a side product. No direct evidence for intercalation of zinc ions was observed. Electrochemical experiments in different aqueous/organic electrolytes has shown that proton intercalation plays a significant role in the charge-storage mechanism, while the activation process itself proceeds, most likely, through the formation of Zn-species at the electrode surface. K E Y W O R D S activation, aqueous battery, energy storage, hausmannite, Mn 3 O 4 , near neutral electrolyte, Zn/ MnO 2 battery 1 | INTRODUCTION According to a recent forecast by the International Energy Agency (IEA), the overall use of renewables in the global energy portfolio will experience a 20% growth during the 2018 to 2023 period and will reach 12.4% by 2023. 1 IEA further forecasts that the decarbonization of the electricity sector, led by solar PV and wind, will see the fastest growth providing almost 30% of power demand in 2023, an increase of 6% from 2017. 1 Nevertheless, renewables, which are enjoying a rapid global growth, require a parallel development of storage

Highly crystalline ramsdellite MnO2 was tested as a battery cathode material in aqueous Zn-salt (ZnSO4 and Zn(CF3SO3)2) based electrolytes for the first time. The aqueous MnO2/Zn cell has shown excellent performance and reversibility, retaining 65% of its initial capacity for more than 1000 cycles.

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Monitoring bromides (Br−) is of crucial importance since bromates, potential human carcinogens, are formed during ozonation of water containing bromides in concentrations >100 μg L−1. Within this study, silver (Ag) and four carbon-supported Ag catalysts were synthesized by the γ-radiation method and their morphology and structure examined using transmission electron microscopy, X–ray diffraction, and UV-Vis analysis. The nanocatalysts were tested for Br− sensing in aqueous media using cyclic voltammetry. All five Ag materials exhibited electroactivity for sensing of Br− ions, with pure Ag catalyst giving the best response to Br− ions presence in terms of the lowest limit of detection. Sensing of bromides was also explored in tap water after addition of bromides suggesting that herein prepared catalysts could be used for bromides detection in real samples. Furthermore, sensing of other halogen ions, namely, chlorides and iodides, was examined, and response due to chloride presence was recorded.