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1 wileyonlinelibrary.com evolution reaction (OER) is currently the limiting factor on the water splitting due to its sluggish kinetics involving the complex four-electron oxidation process. [3] To this end, the presence of an efficient OER electrocatalyst is essential to obtain an accelerated reaction rate. At present, precious metal-based iridium and ruthenium oxides (i.e., IrO 2 and RuO 2 ) are regarded as the OER catalysts benchmarks, [4] but their scarcity and high cost have hindered their wide-scale applications. IrO 2 and RuO 2 catalysts additionally show poor stability during long-term operation in alkaline solutions. [5] As such, tremendous efforts have been devoted to develop low-cost and earth-abundant alternative OER catalysts with high activity and good stability.Over the past few decades, due to their compositional and structural flexibility, precious metal-free perovskitetype oxides with a general formula of ABO 3 (A = alkaline-earth or rare-earth metals and B = transition metals) have attracted interests in various applications, e.g., solid oxide fuel cells (SOFCs), oxygen permeation membranes, metalair batteries, and supercapacitors. [6] Most recently, they were reported to also exhibit high OER activity in an alkaline solution. [7] Rossmeisl group and Koper group theoretically calculated that SrCoO 3 parent oxide would deliver the highest OER activity among LaMO 3 and SrMO 3 (M = transition metals) parent oxides via density functional theory calculations. [8] Shao-Horn and co-workers reported that one of the Developing cost-effective and efficient electrocatalysts for oxygen evolution reaction (OER) is of paramount importance for the storage of renewable energies. Perovskite oxides serve as attractive candidates given their structural and compositional flexibility in addition to high intrinsic catalytic activity. In a departure from the conventional doping approach utilizing metal elements only, here it is shown that non-metal element doping provides an another attractive avenue to optimize the structure stability and OER performance of perovskite oxides. This is exemplified by a novel tetragonal perovskite developed in this work, i.e., SrCo 0.95 P 0.05 O 3-δ (SCP) which features higher electrical conductivity and larger amount of O 2 2− /O − species relative to the non-doped parent SrCoO 3-δ (SC), and thus shows improved OER activity. Also, the performance of SCP compares favorably to that of well-developed perovskite oxides reported. More importantly, an unusual activation process with enhanced activity during accelerated durability test (ADT) is observed for SCP, whereas SC delivers deactivation for the OER. Such an activation phenomenon for SCP may be primarily attributed to the in situ formation of active A-site-deficient structure on the surface and the increased electrochemical surface area during ADT. The concept presented here bolsters the prospect to develop a viable alternative to precious metal-based catalysts.

Solid-oxide fuel cells (SOFCs) are electricity generators that can convert the chemical energy in various fuels directly to the electric power with high efficiency. Recent advances in materials and related key components for SOFCs operating at ≈500 °C are summarized here, with a focus on the materials, structures, and techniques development for low-temperature SOFCs, including the analysis of most of the critical parameters affecting the electrochemical performance of the electrolyte, anode, and cathode. New strategies, such as thin-film deposition, exsolution of nanoparticles from perovskites, microwave plasma heating, and finger-like channeled electrodes, are discussed. These recent developments highlight the need for electrodes with higher activity and electrolytes with greater conductivity to generate a high electrochemical performance at lower temperatures.

A significant number of biosorption studies on the removal of heavy metal from aqueous solutions have been conducted worldwide. Nearly all of them have been directed towards optimizing biosorption parameters to obtain the highest removal efficiency while the rest of them are concerned with the biosorption mechanism. Combinations of FTIR, SEM-EDX, TEM as well as classical methods such as titrations are extremely useful in determining the main processes on the surfaces of biosorbents. Diverse functional groups represented by carboxyl, hydroxyl, sulfate and amino groups play significant roles in the biosorption process. Solution pH normally has a large impact on biosorption performance. In brief, ion exchange and complexation can be pointed out as the most prevalent mechanisms for the biosorption of most heavy metals.

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