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Summary: In this paper, a type of high‐performance nanostructure Fe2O3 (Fe2O3‐arc) is synthesized via a novel direct current electric arc method and employed as a sulfur‐wrapping matrix for lithium‐sulfur batteries. Scanning electron microscopy reveals Fe2O3‐arc has a granular morphology and the crystal size can be controlled below 100 nm. X‐ray diffraction patterns and Raman spectrums show that Fe2O3‐arc displays obvious confusion, but continues to have a typical Fe2O3 crystal structure with preferentially growing on the (110) crystal plane. After sulfur loading, stable physical entrapment and chemical interaction can be established between sulfur and Fe2O3‐arc matrix. The electrochemical test indicates the sulfur composite cathode with Fe2O3‐arc as matrix at the loading mass ratio to 1:3 has a stable and conventional sulfur electrochemical process. The initial discharge specific capacities can achieve 720.59, 653.79 and 540.32 mAh.g−1 at 0.1, 0.2 and 0.5 C current rates, respectively. And after 200 cycles, the capacity retention rate can be at 62.23%. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) organic–inorganic perovskite hybrid materials with enhanced stability have attracted wide attention in optoelectronic field in recent years. Efforts of exploring new 2D perovskites with various organic or inorganic components have been devoted to further improve their solar cell efficiencies. In this work, three structurally similar spacer cations of phenylethylammonium (PEA), 4-bromophenylethylammonium (BPEA) and 4-chlorophenylethylammonium (CPEA) are selected to prepare multilayered 2D perovskites. It is found that the introduction of halogen atoms in the organic cations positively influences the film quality, light absorption, charge transport, device performance and moisture stability of the resulting perovskites. The (BPEA)2(MA)4Pb5I16 and (CPEA)2(MA)4Pb5I16 perovskites exhibit efficiencies of 7.38% and 10.88%, respectively, which are much higher than that of (PEA)2(MA)4Pb5I16 (3.98%). Owning to the larger size and bigger electronegativity of halogen atom in spacer cations, the PCE of unsealed BPEA- and CPEA-based 2D perovskite devices maintains 73% and 63% of their original efficiency after 720 h exposure to 60% humid air, while the PEA-based 2D device decreases to 52% of its initial PCE. Our work demonstrates new insight to modify the quality and stability of 2D perovskite hybrids, highlighting the validity of molecule design of organic cations in improving the efficiency and stability of 2D perovskite solar cells. [ABSTRACT FROM AUTHOR]

Summary: An ideal catalyst material in the air electrode can reduce the over‐potentials and obtain an excellent electrochemical performance for lithium‐oxygen batteries. In this paper, Ag modified NixAlyMnzO2 polynary metal oxides (Ag@NAM) is synthesized by a facile precipitation method and as a bifunctional catalyst for high performance air electrode of lithium‐oxygen batteries. X‐ray diffraction and Raman spectrum test results show that the Ag@NAM catalyst has high crystallinity, which can prevent the lattice distortion caused by manganese dissolution and Ag staying on the surface can change the bond energy in order to supply some special catalytic effects. Through scanning electron microscope observation, Ag@NAM with the proportion of Ag and NixAlyMnzO2 polynary metal oxides to 8.5:1.5 has regular block morphology and uniform grain size. When an air electrode catalyst for lithium‐oxygen batteries, Ag@NAM can provide a large electrochemical reaction space along with enough oxygen atoms and lithium ions for electrocatalytic and electrochemical reactions. Specific discharge capacities can achieve to 6834.83, 6477.07, and 4357.14 mAh g−1 at 0.1, 0.2, and 0.3 mA cm−2 current densities, respectively. In addition, this air electrode can carry out stable 28‐time charge and discharge cycles. Hence, we feel that Ag@NAM catalyst can play an ideal bifunctional catalytic role and effectively reduce the polarization resistance. [ABSTRACT FROM AUTHOR]

Summary: Lithium‐sulfur batteries have attracted much attention for a long time owing to their high theoretical specific capacity. In this paper, a type of highly active Mo doping TiO2 as sulfur loaded matrix material has been synthesized by a facile solvothermal method. X‐ray diffraction and Raman spectrum tests show that Mo atom can enter into the interlayer of TiO2 crystal face and increase the interplanar spacing of titanium dioxide in order to possess a higher electrochemical activity. Small particles morphology and uniform particle size can be evidently observed by scanning electron microscope and after sulfur loading (1:1), it still retains the similar morphology as matrix material. This illustrates that a considerable amount of sulfur has penetrated into the matrix material in order to achieve the ideal sulfur loading effect. When used as electrode active material, it displays the lowest electrochemical and concentration polarization resistance and the specific capacities can reach 1483.08, 1208.57, and 1004.17 mAh g−1 at 0.1, 0.2, and 0.5 C current rates and after 150 cycles, the capacity retention is over 60%. When the sulfur loading mass ratio increases to 1:2 (Mo/TiO2:S), the sulfur composite cathode still maintains considerable lithium‐ion diffusion channels and 753.54 mAh g−1 of specific discharge capacity at 0.5 C current rate. [ABSTRACT FROM AUTHOR]