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One of the major challenges that hinder the practical application of water electrolysis lies in the design of advanced electrocatalysts toward the anodic oxygen evolution reaction (OER). In this work, a pure Co-based precatalyst of CoOOH/brownmillerite derived from the surface activation of brownmillerite by a surface acid etching method exhibits high activity and stable electrical properties toward the OER. Different from oxyhydroxide derived from in situsurface reconstruction during the electrochemical process, the growth of highly crystalline CoOOH from the brownmillerite surface enables rational control over the surface/bulk structure as well as the concentration of active sites, and this structure can be well maintained and serve as highly active sites. The catalyst shows a low overpotential of 320 mV to obtain 10 mA cm–2and high stability in an alkaline electrolyte for the OER, which is comparable to the majority of Co-based electrocatalysts. Moreover, the appropriate interfacial interaction of the composite catalysts greatly contributes to the hydroxide insertion to improve water oxidation ability. This work proposes an effective strategy to develop high-performance metal oxide-based materials for the OER.

Effective neuroprotective agents are required to prevent neurological damage caused by reactive oxygen species (ROS) generated by cerebral ischemia‐reperfusion injury (CIRI) following an acute ischemic stroke. Herein, it is aimed to develop the neuroprotective agents of cerium oxide loaded with platinum clusters engineered modifications (Ptn‐CeO2). The density functional theory calculations show that Ptn‐CeO2could effectively scavenge ROS, including hydroxyl radicals (·OH) and superoxide anions (·O2−). In addition, Ptn‐CeO2exhibits the superoxide dismutase‐ and catalase‐like enzyme activities, which is capable of scavenging hydrogen peroxide (H2O2). The in vitro studies show that Ptn‐CeO2could adjust the restoration of the mitochondrial metabolism to ROS homeostasis, rebalance cytokines, and feature high biocompatibility. The studies in mice CIRI demonstrate that Ptn‐CeO2could also restore cytokine levels, reduce cysteine aspartate‐specific protease (cleaved Caspase 3) levels, and induce the polarization of microglia to M2‐type macrophages, thus inhibiting the inflammatory responses. As a result, Ptn‐CeO2inhibits the reperfusion‐induced neuronal apoptosis, relieves the infarct volume, reduces the neurological severity score, and improves cognitive function. Overall, these findings suggest that the prominent neuroprotective effect of the engineered Ptn‐CeO2has a significant neuroprotective effect and provides a potential therapeutic alternative for CIRI. This study reports a cerium oxide loaded with platinum clusters (Ptn‐CeO2) nano‐heterostructure for the treatment of cerebral ischemia‐reperfusion injury. In addition to efficiently scavenging reactive oxygen species, Ptn‐CeO2remodels the in vivo immune‐inflammatory microenvironments and prevents neuronal apoptosis, and ultimately improves neurobehavioral manifestations. This strategy offers a potential option for clinical applications.

Under ambient conditions, the only known valence state of calcium ions is +2, and the corresponding crystals with calcium ions are insulating and nonferromagnetic. Here, using cryo-electron microscopy, we report direct observation of two-dimensional (2D) CaCl crystals on reduced graphene oxide (rGO) membranes, in which the calcium ions are only monovalent (i.e. +1). Remarkably, metallic rather than insulating properties are displayed by those CaCl crystals. More interestingly, room-temperature ferromagnetism, graphene–CaCl heterojunction, coexistence of piezoelectricity-like property and metallicity, as well as the distinct hydrogen storage and release capability of the CaCl crystals in rGO membranes are experimentally demonstrated. We note that such CaCl crystals are obtained by simply incubating rGO membranes in salt solutions below the saturated concentration, under ambient conditions. Theoretical studies suggest that the formation of those abnormal crystals is attributed to the strong cation-π interactions of the Ca cations with the aromatic rings in the graphene surfaces. The findings highlight the realistic potential applications of such abnormal CaCl material with unusual electronic properties in designing novel transistors and magnetic devices, hydrogen storage, catalyzers, high-performance conducting electrodes and sensors, with a size down to atomic scale.Counter to conventional wisdom, two-dimensional CaCl crystals with +1 calcium ions have been observed, which show unexpected metallicity, room-temperature ferromagnetism, heterojunction, piezoelectricity-like property, and distinct hydrogen storage and release capability.