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Sodium-ion intercalation oxides generally possess high compositional diversity according to their different stacking sequences. The sodium diffusion pathway in layered P-type materials used in sodium-ion batteries is open, which can increase their rate capability by directly transmitting Na+ between adjacent triangular prismatic channels, rather than passing through an intermediate tetrahedral site in O-type structure. However, how the structure chemistry of the P-type oxides determines their electrochemical properties has not been fully understood yet. Herein, by comparing the crystalline structures, electrochemical behaviors, ion/electron transport dynamics of a couple of P-type intercalation cathodes, P2-Na2/3Ni1/3Mn2/3O2 and P3-Na2/3Ni1/3Mn2/3O2 with the same compositions, we demonstrate experimentally and computationally that the P2 phase delivers better cycling stability and rate capability than the P3 counterpart due to the predominant contribution of the faster intrinsic Na diffusion kinetics in the P2 bulk. We also point out that it is the electronic conductivity that captures the key electrochemistry of layered P3-type materials and makes them possible to enhance the sodium storage performance. The results reveal that the correlation between stacking structure and functional properties in two typical layered P-type cathodes, providing new guidelines for preparing and designing alkali-metal layered oxide materials with improved battery performance. [ABSTRACT FROM AUTHOR]

Long-cycling of anode nanomaterials is crucial for promoting lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) towards the further practical applications. Anode nanomaterials, such as transition-metal sulfides (TMSs), are conventionally prepared via sulfuration with additional conventional sulfur sources. Herein, we prepare bimetallic sulfide (Co0.83Fe0.17)9S8 nanoparticles confined within coral-like N,S co-doped carbon scaffolds ((Co0.83Fe0.17)9S8/N,S–C) as anode nanomaterials for LIBs and SIBs, without introducing additional sulfur source. The (Co0.83Fe0.17)9S8/N,S–C composite is eco-synthesized by direct pyrolysis of a mixture of metanilic acid intercalated CoFe-LDH and acid yellow 49 (AY49), thus endowed with the integrated advantageous features: bimetallic (Co0.83Fe0.17)9S8, N,S co-doped carbon scaffold (14.2 wt%), the appropriate specific surface area and mesoporous structure. The electrochemical testing demonstrates that the composite exhibits a reversible capacity of 948.8 mAh g–1 after 80 cycles at 0.1 A g–1 for LIBs, and a decent reversible capacity of 392.9 mAh g–1 after 50 cycles at 0.1 A g–1 for SIBs, which are both superior to those of the Co9S8/N,S–C counterpart. The enhancement is supported by the result of low charge resistance determined by electrochemical impedance spectroscopy. Our results may provide an eco-efficient synthetic method for the preparation of TMSs for energy storage. [ABSTRACT FROM AUTHOR]

Non-noble electrocatalysts (such as transition metal sulfides) have been attractive to substitute noble-metal catalysts for oxygen evolution reaction (OER) to advance the practical application of clean energy. Herein, a Fe-doped CoS2 nanoparticles supported CoS2 microspheres@N-doped carbon (Fe-CoS2/CoS2@NC) is prepared as an efficient OER electrocatalyst. The Fe-CoS2/CoS2@NC composite is derived by sulfurizing the metanilic-intercalated Co(OH)2 microspheres decorated with binary active CoFe-Prussian blue analogue (CoFe-PBA) nanoparticles. The obtained composite combines the advantageous characteristics for enhancing electrocatalytic performances: binary active Fe-CoS2 derived from CoFe-PBA, active CoS2, N-doped carbon scaffold to improve electronic conductivity, the appropriate specific surface area and meso/macroporous size distribution to afford rich active sites. The Fe-CoS2/CoS2@NC requires an overpotential of 300 mV to reach a current density of 10 mA cm−2 with a Tafel slope of 72 mV dec−1 in 1.0 M KOH, outperforming those of NC/CoS2, NC/Fe-CoS2 and CoS2. Furthermore, the enhancement is experimentally supported by the low charge-transfer resistance and the large electrochemical active surface area during the OER. The synthesis approach could be extended to provide a tunable hydroxide/PBAs precursor-based approach for designing and preparing hierarchical structures as electrocatalysts. [ABSTRACT FROM AUTHOR]

Carbonaceous materials have been promising for further advancing the lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), but suffer from a relatively low specific capacity. One effective improvement strategy by doping heteroatoms is typically used. Herein, a preparation of low-content (26.7 wt%) Ni-doped CoS2 embedded N,P-codoped biomass-derived carbon spheres ((Ni0.5S0.5)S2@NPCS) as anode materials for LIBs and SIBs is demonstrated by the sulfuration of Ni, Co salt-loaded yeast spheres. The resultant composite is endowed with the following advantages: N,P-codoped carbon sphere, low-content bimetallic (Ni0.5Co0.5)S2 encapsulated with graphic shell. The composite indeed delivers highly enhanced electrochemical performances (a capacity of 600 mAh g-1 at 0.5 A g-1 after 450 cycles and 480 mAh g-1 at 1 A g-1 after 200 cycles) compared with the counterparts of CoS2@NPCS and pristine carbon spheres (NPCS) for LIBs. In addition, a decent reversible capacity for SIBs is achieved. The enchantment is supported by the result of electrochemical impedance spectra. The results demonstrate the biomass-derived carbon sphere can promise the preparation of promising anodes for energy storage. [ABSTRACT FROM AUTHOR]

Catalysts or support to catalysts based on layered double hydroxides (LDHs) have been widely investigated in the last few years. Supported Au nanoparticles (NPs), prepared typically by a homogeneous deposition-precipitation technique, have been utilized as catalysts with high activity and selectivity for styrene epoxidation. We herein present a preparation of chemically reduced and cost-saving Ag NPs on the LDH support used as catalyst for styrene epoxidation. A proper reaction condition is optimized, for example, a loading of 2.67 wt% Ag, a conversion temperature of 82 °C, and a conversion time of 8 h. The Ag/LDH catalyst exhibits enhanced reaction selectivity and product yield in comparison with the Au/LDH reported previously. Our results may initiate a facile framework appropriate for noble metallic NPs supported on layered inorganic crystal compounds. [ABSTRACT FROM AUTHOR]

Reports a study on the self-assemblies of 4-hexadecyloxybenzoic acid and 3,4,5-trihexadecyloxybenzoic acid. Use of scanning tunneling microscopy (STM); Investigation of the well-ordered assemblies which have various arrangements; Idea that the structural change results from the different number of substituted alkyl chains on the periphery.

Developing effective heterogeneous metal catalysts with high selectivity and satisfactory activity for chemoselective hydrogenation of alkyne to alkene is of great importance in the chemical industry. Herein, we report our efforts to fabricate TiO2-supported Pd catalysts by a photodeposition method at room temperature for phenylacetylene semihydrogenation to styrene. The resulting Pd/TiO2 catalyst, possessing smaller Pd ensembles with ambiguous lattice fringes and more low coordination Pd sites, exhibits higher styrene selectivity compared to two contrastive Pd/TiO2 samples with larger ensembles and well-organized crystal structure fabricated by deposition-precipitation or photodeposition with subsequent thermal treatment at 300 °C. The sample derived from photodeposition exhibits greatly slow styrene hydrogenation in kinetic evaluation because the disordered structure of Pd particles in photodeposited Pd/TiO2 may prevent the formation of β-hydride phases and probably produce more surface H atoms, which may favor high styrene selectivity. [ABSTRACT FROM AUTHOR]