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Biomedical magnesium (Mg) alloys remain a challenge for their mainstream application, because the combination of bio‐mechanical stress and corrosive physiological environment leading to stress corrosion cracking (SCC). It is crucial to avoid the sudden brittle fracture of Mg alloys in vivo for predicting their service duration. However, the key factors, such as surface or physiological environment features, determining the origination or propagation of SCC behavior are still unclear. In the present study, a prefabricated surface defects coating was prepared by the phytic acid (PA, C6H18O24P6) conversion treatment. Four mimicking physiological media were used, ranging from simple to equivalent (Dulbecco's Modified Eagle Medium and Protein [DMEM+Pro]). The results showed that the PA film with numerous micro‐cracks provided limited protective ability in synthetic biological media. A striking finding was determined that although initial high corrosion rate of samples in DMEM+Pro led to an increased SCC nucleation, significant ductile fracture with elongation to failure (14.86%) was observed. Combined with the fracture features, the adsorption or deposition of biological composition into the tunnel of SCC cracks significantly inhibited the hydrogen embrittlement (HE) behavior. These results indicate that preventing the propagation of SCC crack by biological composition, rather than nucleation, plays a key role in avoiding the sudden fracture of Mg alloys. It provides a novel perspective to determine the non‐brittle fracture of Mg alloys for biomedical applications. Highlights: Prefabricated surface‐defective Mg novelty used to study stress corrosion crackingConfirming ductile fracture of Mg alloy in vitro organic‐containing mimic mediumInhibiting the micro‐crack propagation relied on biological composition depositionThe crack propagation than nucleation plays a key role in avoiding brittleness [ABSTRACT FROM AUTHOR]

Heteroatom doping in carbon matrices has been widely used to prepare efficient carbonaceous electrocatalysts. Biochar‐assisted water electrolysis (BAWE) is a promising hydrogen production method that can efficiently utilize waste biomass. However, it is often limited by the slow anode biochar oxidation reaction (BOR). In addition, pure biochar typically lacks enough active catalytic sites; hence, its electrochemical reactivity is unsatisfactory. Herein, Ni is doped into bagasse biochar to improve its BOR. Its electrochemical properties and hydrogen production performance are measured using linear sweep voltammetry, electrochemical impedance spectroscopy, and chronopotentiometry. The reaction characteristics of the bagasse biochar are analyzed. The impact of its physiochemical properties on its oxidation process is discussed. Compared to the undoped biochar, the Ni‐doped biochar shows a larger specific surface area, a higher degree of graphitization, and stronger biochar oxidation reactivity (including a lower onset potential and larger electric current density), which significantly increase the electric current density and hydrogen production. This study provides a beneficial strategy for improving BAWE. [ABSTRACT FROM AUTHOR]

The inadequate utilization of low‐grade energy from industrial waste heat and solar energy calls for an efficient thermochemical heat storage material. The fabrication of a low‐cost but highly efficient composite comprising highly porous biochar and LiOH·H2O nanoparticles for heat storage applications is reported. The biochar is prepared by the KOH‐assisted pyrolysis of dead banyan leaves, and its microstructure and surface properties can be finely tuned by varying the KOH‐to‐biomass ratio. Such biochar can be mediated to possess a large specific surface area and total pore volume reaching as high as 1255.03 m2 g−1 and 3.65 cm3 g−1, respectively, superior to most previously reported biochar/biocarbon derived from different kinds of waste biomass. Besides, adequate functional groups and a hierarchical porous structure consisting of micropores and mesopores are demonstrated in the prepared biochar. The subsequent hydrothermal reaction with a short duration yields a biochar‐LiOH·H2O composite, where LiOH·H2O can be homogeneously immobilized with a nanoscale size within the porous biochar matrix. Thus, an enormous biochar/LiOH·H2O nanoparticles interface can be obtained, resulting in fast hydration reactions with water molecules. Consequently, a significant heat storage density of as high as 3089.6 kJ kg−1 is achieved within only 10 min, outstripping some recently reported thermochemical heat storage systems. [ABSTRACT FROM AUTHOR]

To solve the problems of fast‐charging of lithium‐ion batteries in essence, development of new electrode materials with higher lithium‐ion diffusion coefficients is the key. In this work, a novel flower‐like Ni@SnNi structure is synthesized via a two‐step process design, which consists of the fabrication of Ni cores by spray pyrolysis followed by the formation of SnNi shells via a simple oxidation–reduction reaction. The obtained Ni@SnNi composite exhibits an initial capacity of ≈693 mA h g−1 and a reversible capacity of ≈570 mA h g−1 after 300 charge/discharge cycles at 0.5 C, and maintains 450 mA h g−1 even at a high rate of 3 C. Further, it is proved that a Ni@SnNi composite possesses high lithium‐ion diffusion coefficient (≈10−8), which is much higher than those (≈10−10) reported previously, which can be mainly attributed to the unique flower‐like Ni@SnNi structure. In addition, the full cell performance (Ni@SnNi‐9h/graphite vs LiCoO2) with a capacity ratio of 1.13 (anode/cathode) is also tested. It is found that even at 2 C rate charging/discharging, the capacity retention at 100 cycles is still close to 89%. It means that Ni@SnNi‐9h is a promising anode additive for lithium‐ion batteries with high energy density and power density. [ABSTRACT FROM AUTHOR]