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In this paper, in order to apply the concept of IVI-octahedron sets to MCDGM problems, we define some aggregation operators via IVI-octahedron sets and obtain some their properties. We define some aggregation operators via IVI-octahedron sets and obtain some their properties. We present a MCGDM method with linguistic variables in IVI-octahedron set environment. Finally, we give a numerical examples for MCGDM problems.

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle, where chemical fuels, such as hydrogen, are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies, like cubes, octahedrons, icosahedrons, bipyramids, plates, and polyhedrons, among others, are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs.

Exploring robust catalysts for water oxidation in acidic electrolyte is challenging due to the limited material choice. Iridium (Ir) is the only active element with a high resistance to the acid corrosion during water electrolysis. However, Ir is rare, and its large-scale application could only be possible if the intrinsic activity of Ir could be greatly enhanced. Here, a pseudo-cubic SrCo 0.9 Ir 0.1 O 3-δ perovskite, containing corner-shared IrO6 octahedrons, is designed. The Ir in the SrCo 0.9 Ir 0.1 O 3-δ catalyst shows an extremely high intrinsic activity as reflected from its high turnover frequency, which is more than two orders of magnitude higher than that of IrO 2 . During the electrochemical cycling, a surface reconstruction, with Sr and Co leaching, over SrCo 0.9 Ir 0.1 O 3-δ occurs. Such reconstructed surface region, likely contains a high amount of structural domains with corner-shared and under-coordinated IrO x octahedrons, is responsible for the observed high activity. While water splitting could provide a green means to store energy, there are few materials that can sustain high water oxidation half-reaction rates in acidic electrolytes. Here, authors design a perovskite oxide that generates high performance under-coordinated iridium sites during electrocatalysis.

In this paper, we define the notions of i-octahedron groupoid and i-OLI [resp., i-ORI and i-OI], and study some of their properties and give some examples. Also we deal with some properties for the image and the preimage of i-octahedron groupoids [resp., i-OLI, i-ORI and i-OI] under a groupoid homomorphism. Next, we introduce the concepts of i-octahedron subgroup and normal subgroup of a group and investigate some of their properties. In particular, we obtain a characterization of an i-octahedron subgroup of a group. Finally, we define an i-octahedron subring [resp., i-OLI, i-ORI and i-OI] of a ring and find some of their properties. In particular, we obtain two characterizations of i-OLI [resp., i-ORI and i-OI] of a ring and a skew field, respectively.

Noble metal-based nanomaterials have shown promise as potential enzyme mimetics, but the facet effect and underlying molecular mechanisms are largely unknown. Herein, with a combined experimental and theoretical approach, we unveil that palladium (Pd) nanocrystals exhibit facet-dependent oxidase and peroxidase-like activities that endow them with excellent antibacterial properties via generation of reactive oxygen species. The antibacterial efficiency of Pd nanocrystals against Gram-positive bacteria is consistent with the extent of their enzyme-like activity, that is {100}-faceted Pd cubes with higher activities kill bacteria more effectively than {111}-faceted Pd octahedrons. Surprisingly, a reverse trend of antibacterial activity is observed against Gram-negative bacteria, with Pd octahedrons displaying stronger penetration into bacterial membranes than Pd nanocubes, thereby exerting higher antibacterial activity than the latter. Our findings provide a deeper understanding of facet-dependent enzyme-like activities and might advance the development of noble metal-based nanomaterials with both enhanced and targeted antibacterial activities. Noble metal nanoparticles are potential antibacterial agents, perhaps owing to their enzyme-like activities. Here, the authors find that the exposed facets of palladium nanocrystals demonstrate their specific antibacterial behavior against both Gram-positive and Gram-negative bacteria.

Lithium-excess 3 d -transition-metal layered oxides (Li 1+ x Ni y Co z Mn 1− x − y − z O 2 , >250 mAh g −1 ) suffer from severe voltage decay upon cycling, which decreases energy density and hinders further research and development. Nevertheless, the lack of understanding on chemical and structural uniqueness of the material prevents the interpretation of internal degradation chemistry. Here, we discover a fundamental reason of the voltage decay phenomenon by comparing ordered and cation-disordered materials with a combination of X-ray absorption spectroscopy and transmission electron microscopy studies. The cation arrangement determines the transition metal-oxygen covalency and structural reversibility related to voltage decay. The identification of structural arrangement with de-lithiated oxygen-centred octahedron and interactions between octahedrons affecting the oxygen stability and transition metal mobility of layered oxide provides the insight into the degradation chemistry of cathode materials and a way to develop high-energy density electrodes. There is growing interest in the fundamental understanding of the voltage decay mechanism in Li-excess layered cathode materials. Here, the authors report a multilateral and macroscopic analysis that considers interaction between oxygen and atomic arrangement of Li 1+ x Ni y Co z Mn 1− x − y − z O 2 .

Nonradical Fenton-like catalysis offers opportunities to overcome the low efficiency and secondary pollution limitations of existing advanced oxidation decontamination technologies, but realizing this on transition metal spinel oxide catalysts remains challenging due to insufficient understanding of their catalytic mechanisms. Here, we explore the origins of catalytic selectivity of Fe–Mn spinel oxide and identify electron delocalization of the surface metal active site as the key driver of its nonradical catalysis. Through fine-tuning the crystal geometry to trigger Fe–Mn superexchange interaction at the spinel octahedra, ZnFeMnO₄ with high-degree electron delocalization of the Mn–O unit was created to enable near 100% nonradical activation of peroxymonosulfate (PMS) at unprecedented utilization efficiency. The resulting surface-bound PMS* complex can efficiently oxidize electron-rich pollutants with extraordinary degradation activity, selectivity, and good environmental robustness to favor water decontamination applications. Our work provides a molecule-level understanding of the catalytic selectivity and bimetallic interactions of Fe–Mn spinel oxides, which may guide the design of low-cost spinel oxides for more selective and efficient decontamination applications.

Morphological shape in chemistry and biology owes its existence to anisotropic growth and is closely coupled to distinct functionality. Although much is known about the principal growth mechanisms of monometallic shaped nanocrystals, the anisotropic growth of shaped alloy nanocrystals is still poorly understood. Using aberration-corrected scanning transmission electron microscopy, we reveal an element-specific anisotropic growth mechanism of platinum (Pt) bimetallic nano-octahedra where compositional anisotropy couples to geometric anisotropy. A Pt-rich phase evolves into precursor nanohexapods, followed by a slower step-induced deposition of an M-rich (M = Ni, Co, etc.) phase at the concave hexapod surface forming the octahedral facets. Our finding explains earlier reports on unusual compositional segregations and chemical degradation pathways of bimetallic polyhedral catalysts and may aid rational synthesis of shaped alloy catalysts with desired compositional patterns and properties.

The discovery of various primary ferroic phases in atomically-thin van der Waals crystals have created a new two-dimensional wonderland for exploring and manipulating exotic quantum phases. It may also bring technical breakthroughs in device applications, as evident by prototypical functionalities of giant tunneling magnetoresistance, gate-tunable ferromagnetism and non-volatile ferroelectric memory etc. However, two-dimensional multiferroics with effective magnetoelectric coupling, which ultimately decides the future of multiferroic-based information technology, has not been realized yet. Here, we show that an unconventional magnetoelectric coupling mechanism interlocked with heterogeneous ferrielectric transitions emerges at the two-dimensional limit in van der Waals multiferroic CuCrP 2 S 6 with inherent antiferromagnetism and antiferroelectricity. Distinct from the homogeneous antiferroelectric bulk, thin-layer CuCrP 2 S 6 under external electric field makes layer-dependent heterogeneous ferrielectric transitions, minimizing the depolarization effect introduced by the rearrangements of Cu + ions within the ferromagnetic van der Waals cages of CrS 6 and P 2 S 6 octahedrons. The resulting ferrielectric phases are characterized by substantially reduced interlayer magnetic coupling energy of nearly 50% with a moderate electric field of 0.3 V nm −1 , producing widely-tunable magnetoelectric coupling which can be further engineered by asymmetrical electrode work functions. Two-dimensional multiferroics with effective magnetoelectric coupling has not been realized. Here, the authors find a magnetoelectric coupling mechanism in two-dimensional CuCrP 2 S 6 interlocked with heterogeneous ferrielectric state.

Phase transition dynamics are an important concern in the wide applications of metal halide perovskites, which fundamentally determine the optoelectronic properties and stabilities of perovskite materials and devices. However, a more in-depth understanding of such a phase transition process with real atomic resolution is still limited by the immature low-dose electron microscopy and in situ imaging studies to date. Here, we apply an emergent low-dose imaging technique to identify different phase structures (α, β and γ) in CsPbI 3 nanocrystals during an in-situ heating process. The rotation angles of PbI 6 octahedrons can be measured in these images to quantitatively describe the thermal-induced phase distribution and phase transition. Then, the dynamics of such a phase transition are studied at a macro time scale by continuously imaging the phase distribution in a single nanocrystal. The structural evolution process of CsPbI 3 nanocrystals at the particle level, including the changes in morphology and composition, is also visualized with increasing temperature. These results provide atomic insights into the transition dynamics of perovskite phases, indicating a long-time transition process with obvious intermediate states and spatial distribution that should be generally considered in the further study of structure-property relations and device performance. Phase transition dynamics are an important concern in the wide applications of metal halide perovskites. Here authors apply low-dose imaging technique to reveal the phase transition dynamics of CsPbI 3 during in-situ heating process with atomic resolution.