Explore the vast range of titles available.

Water is the only available fossil-free source of hydrogen. Splitting water electrochemically is among the most used techniques, however, it accounts for only 4% of global hydrogen production. One of the reasons is the high cost and low performance of catalysts promoting the oxygen evolution reaction (OER). Here, we report a highly efficient catalyst in acid, that is, solid-solution Ru‒Ir nanosized-coral (RuIr-NC) consisting of 3 nm-thick sheets with only 6 at.% Ir. Among OER catalysts, RuIr-NC shows the highest intrinsic activity and stability. A home-made overall water splitting cell using RuIr-NC as both electrodes can reach 10 mA cm −2 geo at 1.485 V for 120 h without noticeable degradation, which outperforms known cells. Operando spectroscopy and atomic-resolution electron microscopy indicate that the high-performance results from the ability of the preferentially exposed {0001} facets to resist the formation of dissolvable metal oxides and to transform ephemeral Ru into a long-lived catalyst. Ru is one of the most active metals for oxygen evolution reaction, but it quickly dissolves in acidic electrolyte particularly in nanosized form. Here, the authors show that coral-like solid-solution Ru‒Ir consisting of 3 nm-thick sheets with only 6 at% Ir is a long-lived catalyst with high activity.

The effects of ball milling on the ionic conduction properties of LiI are investigated. It is found that ball milling drastically increased the conductivity of LiI to 1 × 10−5 S/cm at room temperature. The activation energy for ion conduction is not significantly changed. The local structure of ball-milled LiI is investigated by a pair distribution function (PDF) analysis based on the X-ray total scattering measurement. The nearest neighbor distance of Li+ and I− is shorter than that in the perfect crystal of LiI. The X-ray absorption measurements suggest that the bonding state of I− is not significantly changed by ball milling. These results indicate that the disordered local structure of Li+ around I− is one of the origins of the enhancement of the conductivity of LiI by ball milling. An all-solid-state cell of Li/amorphous Si film (50 nm in thickness) is constructed using ball-milled LiI as the solid electrolyte. The charge–discharge performances are excellent. It is shown that a charge–discharge capacity of approximately 3500 mAh/g can be maintained for 30 cycles with Coulombic efficiencies of over 99%. It should be emphasized that no degradation of the reduction stability is found in the ball-milled LiI with improved conductivity.

Sulfide glasses can exhibit notable ionic conductivity because of annealing-associated crystallization. One well-known example is Li 7 P 3 S 11 . Our research showed that adding bromine (Br) to Li 3 PS 4 sulfide glass results in a similar crystal structure and high ionic conductivity comparable to that of another compound Li 10 GeP 2 S 12 . This structure differs from the PS 4 anion framework of Li 3 PS 4 . In addition, the ionic conductivity decreases owing to a structural transition to the β-phase. Herein, we present our findings on the local structure of Li 3 PS 4 sulfide glass and its crystallized glass ceramic with the addition of Br. This analysis relies on the pair distribution function analysis obtained from high-energy X-ray diffraction. Moreover, using the bond valence sum method, we verified that incorporating Br promotes the formation of Li ionic conduction pathways. Our results indicate that precise control over the anion molecular structure by introducing halogens holds promise for achieving high Li-ion conductivity.

Bimodal behavior in the translational order of silicon’s second shell in SiO 2 liquid at high temperatures and high pressures has been recognized in theoretical studies, and the fraction of the S state with high tetrahedrality is considered as structural origin of the anomalous properties. However, it has not been well identified in experiment. Here we show experimental evidence of a bimodal behavior in the translational order of silicon’s second shell in SiO 2 glass under pressure. SiO 2 glass shows tetrahedral symmetry structure with separation between the first and second shells of silicon at low pressures, which corresponds to the S state structure reported in SiO 2 liquid. On the other hand, at high pressures, the silicon’s second shell collapses onto the first shell, and more silicon atoms locate in the first shell. These observations indicate breaking of local tetrahedral symmetry in SiO 2 glass under pressure, as well as SiO 2 liquid. Understanding the structural origin of the anomalous properties of SiO 2 liquid and glass at high pressures is fundamental in wide range of scientific fields. Here, the authors find experimental evidence of a bimodal behavior in the translational order of silicon’s second shell and breaking of local tetrahedral symmetry in SiO 2 glass under pressure.

We have investigated the structural, optical band gap, and electrical properties of (Fe 2 O 3 ) 0.5 x :(NiO) 1 − 0.5 x ( x  = 0.3, 0.4, 0.5, 0.6 and 0.7) epitaxial thin films grown on an atomically smooth substrate at room temperature. With increasing Fe 2 O 3 content, the rock-salt structure of the thin films transformed to a spinel structure above x  = 0.6. In terms of the local structure, the increased ratio of Fe 2+ ions to Fe 3+ ions indicates that the octahedral sites of FeO were continuously transformed into distorted octahedral and tetrahedral sites. On the other hand, the NiO matrix was not affected by the local structure change. Chemical composition of Fe 2 O 3 :NiO affected the crystal structure, the electrical conductivity and the optical band gap of direct transition (3.35 to 2.99 eV).

In Japan, respiratory syncytial virus (RSV) infection generally has occurred during autumn and winter. However, a possible change in the seasonal trend of RSV infection has been observed recently. The current study was conducted to determine whether the epidemic season of RSV infection in Japan has indeed changed significantly. We used expectation-based Poisson scan statistics to detect periods with high weekly reported RSV cases (epidemic cluster), and the epidemic clusters were detected between September and December in the 2012–2016 seasons while those were detected between July and October in the 2017–2019 seasons. Non-linear and linear ordinary least squares regression models were built to evaluate whether there is a difference in year trend in the epidemic seasonality, and the epidemic season was shifted to earlier in the year in 2017–2019 compared to that in 2012–2016. Although the reason for the shift is unclear, this information may help in clinical practice and public health.

A solid with larger sound speeds usually exhibits higher lattice thermal conductivity. Here, we report an exception that CuP 2 has a quite large mean sound speed of 4155 m s −1 , comparable to GaAs, but single crystals show very low lattice thermal conductivity of about 4 W m −1 K −1 at room temperature, one order of magnitude smaller than GaAs. To understand such a puzzling thermal transport behavior, we have thoroughly investigated the atomic structures and lattice dynamics by combining neutron scattering techniques with first-principles simulations. This compound crystallizes in a layered structure where Cu atoms forming dimers are sandwiched in between P atomic networks. In this work, we reveal that Cu atomic dimers vibrate as a rattling mode with frequency around 11 meV, which is manifested to be remarkably anharmonic and strongly scatters acoustic phonons to achieve the low lattice thermal conductivity. CuP2 has a puzzling thermal transport behavior, with low thermal conductivity but quite large mean sound speeds. Here, the authors conduct a systematical study of the atomic structure and lattice dynamics of CuP2 to reveal the origin, finding a dimer rattling behavior.

Despite the importance of oxygen evolution reaction (OER) catalysts in energy conversion applications, the time-resolved dynamics of their amorphous phases remain elusive. Understanding the structural evolution of OER catalysts is pivotal to improve their design and sustainability and increase the energy conversion efficiency. SrIrO 3 is a promising OER catalyst for achieving high energy conversion efficiencies, but it has not been sufficiently characterized in terms of its phase dynamics during operation. Herein, in-situ total X-ray scattering measurements and pair distribution function analysis are used to probe time-resolved structural changes in an IrO x /SrIrO 3 catalyst during OER, revealing the occurrence of persistent Ir–O bond shortening and dynamic structural interconversions between multiple crystalline phases and an amorphous component. The relative contents of the main crystalline phases—3C-SrIrO 3 (Pnma) and 6H-SrIrO 3 (C2/c)—exhibited synchronized changes, whereas those of an additional C2/c phase and the amorphous component showed opposite trends, suggesting active structural interplay among the phases during the reaction. Furthermore, the observed Ir–O bond shortening under applied potential was attributed to a structural change associated with increased oxidation state of Ir, which is closely related to the local environment at the rate-determining step of OER. Our findings underscore the importance of precisely controlling bond distances and structural dynamics at the atomic scale for enhancing the activity of OER catalysts and provide valuable insights for future catalyst design.

All-solid-state batteries are typically manufactured under high pressure to decrease the resistance of the solid interface. However, until now, there has been a lack of research concerning changes in the structure of solid electrolytes owing to pressurization. Our study addresses this gap by exploring the structural modifications of the sulfide solid electrolyte Li 3 PS 4 under high-pressure conditions. We observed a tendency for PS 4 molecules to converge upon each other in both β -Li 3 PS 4 and g -Li 3 PS 4 crystals when subjected to a pressure of 100 MPa. In g -Li 3 PS 4 , X-ray scattering and pair distribution function analyses following pressure application and subsequent return to ambient conditions remained consistent with pre-compression measurements. Conversely, in β -Li 3 PS 4 crystals, post-pressure X-ray scattering differed from pre-compression measurements, suggesting pressure-induced atomic rearrangement within the crystal lattice. This underscores the importance of accounting for pressure-induced structural changes, especially in computational simulation studies where crystal structures are often assumed to remain static pre- and post-pressurization. Our findings demonstrate that under high pressure, the crystal structure of Li 3 PS 4 slightly changes by approximately 1~2%, rendering it a viable candidate for utilization as a solid electrolyte in all-solid-state batteries.

Sulfide-based solid electrolytes are increasingly recognized as crucial materials for the practical application of all-solid-state batteries. In particular, halogen-rich argyrodites, featuring hybrid doping with chlorine and bromine, demonstrate that the Li-ion conductivity is influenced by the degree of elemental disorder among chlorine, bromine, and sulfur at the anion sites (4a, 4d). This study employed in situ XRD/PDF during the annealing process of sample synthesis to investigate the formation of disorder at these anion sites. Initially, a sulfur-rich argyrodite phase formed at lower annealing temperatures (200–320 °C). Subsequently, in the higher temperature range (320–460 °C), lithium halide amorphization and thermal diffusion led to the formation of a halogen-rich argyrodite phase. This phase is characterized by the substitution of sulfur with halogen at the 4a/4d sites in argyrodites.