High-temperature superconductivity has a range of applications from sensors to energy distribution. Recent reports of this phenomenon in compounds containing electronically active BiS2 layers have the potential to open a new chapter in the field of superconductivity. Here we report the identification and basic properties of two new ternary Bi-O-S compounds, Bi2OS2 and Bi3O2S3. The former is non-superconducting; the latter likely explains the superconductivity at T(c) = 4.5 K previously reported in "Bi4O4S3". The superconductivity of Bi3O2S3 is found to be sensitive to the number of Bi2OS2-like stacking faults; fewer faults correlate with increases in the Meissner shielding fractions and T(c). Elucidation of the electronic consequences of these stacking faults may be key to the understanding of electronic conductivity and superconductivity which occurs in a nominally valence-precise compound.

Despite the fruitful achievements in the development of hydrogen production catalysts with record-breaking performances, there is still a lack of durable catalysts that could work under large current densities (>1000 mA cm−2). Here, we investigated the catalytic behaviors of Sr2RuO4 bulk single crystals. This crystal has demonstrated remarkable activities under the current density of 1000 mA cm−2, which require overpotentials of 182 and 278 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively. These materials are stable for 56 days of continuous testing at a high current density of above 1000 mA cm−2 and then under operating temperatures of 70 °C. The in-situ formation of ferromagnetic Ru clusters at the crystal surface is observed, endowing the single-crystal catalyst with low charge transfer resistance and high wettability for rapid gas bubble removal. These experiments exemplify the potential of designing HER catalysts that work under industrial-scale current density.

We report the successful crystal growth of a previously unknown mixed-metal organic compound (CH3NH3)2AgInBr6.

Metal–organic frameworks (MOFs) provide exceptional chemical tunability and have recently been demonstrated to exhibit electrical conductivity and related functional electronic properties. The kagomé lattice is a fruitful source of novel physical states of matter, including the quantum spin liquid (in insulators) and Dirac fermions (in metals). Small-bandgap kagomé materials have the potential to bridge quantum spin liquid states and exhibit phenomena such as superconductivity but remain exceptionally rare. Here we report a structural, thermodynamic, and transport study of the two-dimensional kagomé metal–organic frameworks Ni3(HIB)2 and Cu3(HIB)2 (HIB = hexaiminobenzene). Magnetization measurements yield Curie constants of 0.989 emu K (mol Ni)−1 Oe–1 and 0.371 emu K (mol Cu)−1 Oe–1, respectively, close to the values expected for ideal S = 1 Ni2+ and S = 1/2 Cu2+. Weiss temperatures of −10.6 and −14.3 K indicate net weak mean field antiferromagnetic interactions between ions. Electrical transport measurements reveal that both materials are semiconducting, with gaps (E g) of 22.2 and 103 meV, respectively. Specific heat measurements reveal a large T-linear contribution γ of 148(4) mJ mol-fu–1 K–2 in Ni3(HIB)2 with only a gradual upturn below ∼5 K and no evidence of a phase transition to an ordered state down to 0.1 K. Cu3(HIB)2 also lacks evidence of a phase transition above 0.1 K, with a substantial, field-dependent, magnetic contribution below ∼5 K. Despite them being superficially in agreement with the expectations of magnetic frustration and spin liquid physics, we ascribe these observations to the stacking faults found from a detailed analysis of synchrotron X-ray diffraction data. At the same time, our results demonstrate that these MOFs exhibit localized magnetism with simultaneous proximity to a metallic state, thus opening up opportunities to explore the connection between the insulating and metallic ground states of kagomé materials in a highly tunable chemical platform.

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Despite the fruitful achievements in the development of hydrogen production catalysts with record-breaking performances, there is still a lack of durable catalysts that could work under large current densities (> 1000 mA cm− 2). In the context of this need, we investigated the catalytic behaviors of Sr2RuO4 (SRO) bulk single crystals with well-defined surface crystal structures, which is a benchmark material to explore exotic metallic states and electronic structures. This single crystal has demonstrated remarkable activities under the current density of 1000 mA cm− 2, which require overpotentials of 182 and 278 mV in 0.5 M H2SO4 and 1 M KOH electrolytes, respectively, after ohmic correction. These values slightly increased to 272 and 354 mV even without iR correction, exhibiting high potential for industrial-scale hydrogen production. The high performance is also evidenced by the 56 days of continuous testing at a high current density of above 1000 mA cm− 2 and then under operating temperatures of 70 ℃ for alkaline electrolysis. The in-situ formation of ferromagnetic Ru clusters at the crystal surface is critical for the outstanding catalytic activity, endowing the single-crystal catalyst with low charge transfer resistance and high wettability for rapid gas bubble removal. Density functional theory calculations indicate that SRO gains electrons from the Ru clusters, thus leading to the thermodynamically favorable hydrogen desorption for the rapidly modified catalysts. More generally, our experiment exemplifies the potential of designing novel HER catalysts that work under industrial-scale current density.

Stacking Variants and Superconductivity in the Bi-O-S System. -The new compounds Bi2OS2 (I) and Bi3O2S3 (II) are prepared from mixtures of Bi2S3, Bi2O3, and S (430-520°C, 10-17 h) and characterized by powder XRD and magnetic measurements. (I) is non-superconducting, whereas (II) is a superconductor with a critical temperature of 4.5 K. Superconductivity rapidly disappears as Bi2OS2-like stacking faults are introduced in (II). -(PHELAN, W. A.; WALLACE, D. C.; ARPINO, K. E.; NEILSON, J. R.; LIVI, K. J.; SEABOURNE, C. R.; SCOTT, A. J.; MCQUEEN*, T. M.; J. Am. Chem. Soc. 135 (2013) 14, 5372-5374, http://dx.