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Detecting H 2 S in oxygen-deficient conditions is vital for identifying leaks in SF 6 -insulated electrical equipment. Current infrared-based detection methods are expensive and sensitive to environmental conditions, highlighting the necessity for cost-effective and stable gas sensors. Existing gas sensors based on semiconducting metal oxides (SMOXs) are limited by redox reactions with oxygen and require high operating temperatures. Here, we introduce a room-temperature (RT) H 2 S sensor for oxygen-deficient environments using the intrinsic conducting two-dimensional (2D) metal-organic framework (MOF), Co 1.8 Ni 1.2 (hexaiminotriphenylene) 2 [Co 1.8 Ni 1.2 (HITP) 2 ], overcoming the limitations of SMOX gas sensors. Remarkably, Co 1.8 Ni 1.2 (HITP) 2 sensors exhibit exceptional selectivity for H 2 S with negligible cross-responses and a sensitivity drift of less than 4.13% in an SF 6 atmosphere over 60 days. The Co 1.8 Ni 1.2 (HITP) 2 gas sensor shows significant promise for real-time and stable monitoring of H 2 S gas in oxygen-deficient environments.

Efficient gas sensors are critical for environmental monitoring and industrial safety. While metal oxide semiconductor (MOS) sensors are cost-effective, they struggle with poor selectivity, high operating temperatures, and limited stability. Electrochemical sensors, though selective and energy-efficient, face high costs, and stability issues due to precious metal catalysts like platinum on carbon (Pt/C). Herein, a novel, cost-effective electrochemical sensor using nitrogen-doped indium oxide In 2 O 3- x N 2 x /3 V x /3 (0.01≤x≤0.14), synthesized with varying nitriding times is presented. The optimized In 2 O 3 N-40 min sensor demonstrates a remarkable response current of 771 nA to 10 ppm nitrogen dioxide (NO 2 ) at ambient temperature, with outstanding long-term stability (over 30 days) and rapid response/recovery times (5/16 s). Compared to Pt/C sensors, it shows 84% and 67% reductions in response and recovery times, respectively, and maintains 98% performance after a month, versus 68% for Pt/C. This cost-effective sensor presents a promising alternative for electrochemical gas sensing, eliminating the need for precious metal catalysts., (© 2024 Wiley‐VCH GmbH.)

Layered perovskites with Ruddlesden-Popper-type structures are fundamentally important for low-dimensional properties, for example, photovoltaic hybrid iodides and superconducting copper oxides. Many such halides and oxides are known, but analogous nitrides are difficult to stabilize due to the high cation oxidation states required to balance the anion charges. Here we report the high-pressure synthesis of three single-layer Ruddlesden-Popper (K 2 NiF 4 type) nitrides-Pr 2 ReN 4 , Nd 2 ReN 4 and Ce 2 TaN 4 -along with their structural characterization and properties. The R 2 ReN 4 materials (R = Pr and Nd) are metallic, and Nd 2 ReN 4 has a ferromagnetic Nd 3+ spin order below 15 K. Thermal decomposition gives R 2 ReN 3 with a Peierls-type distortion and chains of Re-Re multiply bonded dimers. Ce 2 TaN 4 has a structural transition driven by octahedral tilting, with local distortions and canted magnetic Ce 3+ order evidencing two-dimensional Ce 3+ /Ce 4+ charge ordering correlations. Our work demonstrates that Ruddlesden-Popper nitrides with varied structural, electronic and magnetic properties can be prepared from high-pressure synthesis, opening the door to related layered nitride materials., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Strategies for discovery of high-performance electrocatalysts are important to advance clean energy technologies. Metastable phases such as low temperature or interfacial structures that are difficult to access in bulk may offer such catalytically active surfaces. We report here that the suboxide Zr 3 O, which is formed at Zr-ZrO 2 interfaces but does not appear in the experimental Zr-O phase diagram exhibits outstanding oxygen reduction reaction (ORR) performance surpassing that of benchmark Pt/C and most transition metal-based catalysts. Addition of Fe 3 C nanoparticles to give a Zr-Zr 3 O-Fe 3 C/NC catalyst (NC=nitrogen-doped carbon) gives a half-wave potential (E 1/2 ) of 0.914 V, outperforming Pt/C and showing only a 3 mV decrease after 20,000 electrochemical cycles. A zinc-air battery (ZAB) using this cathode material has a high power density of 241.1 mW cm -2 and remains stable for over 50 days of continuous cycling, demonstrating potential for practical applications. Zr 3 O demonstrates that interfacial or other phases that are difficult to stabilize may offer new directions for the discovery of high-performance electrocatalysts., (© 2024 Wiley-VCH GmbH.)

High pressure high temperature treatments of the composition CaMnMnTeO 6 are found to yield only an A 2 BB'O 6 -type double perovskite (Ca 0.5 Mn 0.5 ) 2 MnTeO 6 , rather than a AA'BB'O 6 double double perovskite with A- and B- site cation order as found in analogs CaMnMnReO 6 and CaMnMnWO 6 with similar cation sizes. Double perovskite (Ca 0.5 Mn 0.5 ) 2 MnTeO 6 adopts a monoclinic structure in space group P2 1 /n with a framework of highly tilted MnO 6 and TeO 6 octahedra enclosing disordered Ca 2+ and Mn 2+ cations. Magnetic measurements show that (Ca 0.5 Mn 0.5 ) 2 MnTeO 6 is a highly frustrated spin glass with a freezing transition at 5 K, and no long-range spin order is apparent by neutron diffraction at 1.6 K., (© 2024 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

Three new nitrides La 3 MN 5 (M=Cr, Mn, and Mo) have been synthesized using a high pressure azide route. These are the first examples of ternary Cs 3 CoCl 5 -type nitrides, and show that this (MN 4 )NLa 3 antiperovskite structure type may be used to stabilise high oxidation-state transition metals in tetrahedral molecular [MN 4 ] n- nitridometallate anions. Magnetic measurements confirm that Cr and Mo are in the M 6+ state, but the M=Mn phase has an anomalously small paramagnetic moment and large cell volume. Neutron powder diffraction data are fitted using an anion-excess La 3 MnN 5.30 model (space group I4/mcm, a=6.81587(9) Å and c=11.22664(18) Å at 200 K) in which Mn is close to the +7 state. Excess-anion incorporation into Cs 3 CoCl 5 -type materials has not been previously reported, and this or other substitution mechanisms may enable many other high oxidation state transition metal nitrides to be prepared., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The ocean, a vast hydrogen reservoir, holds potential for sustainable energy and water development. Developing high-performance electrocatalysts for hydrogen production under harsh seawater conditions is challenging. Here, we propose incorporating a protective V 2 O 3 layer to modulate the microcatalytic environment and create in situ dual-active sites consisting of low-loaded Pt and Ni 3 N. This catalyst demonstrates an ultralow overpotential of 80 mV at 500 mA cm -2 , a mass activity 30.86 times higher than Pt-C and maintains at least 500 hours in seawater. Moreover, the assembled anion exchange membrane water electrolyzers (AEMWE) demonstrate superior activity and durability even under demanding industrial conditions. In situ localized pH analysis elucidates the microcatalytic environmental regulation mechanism of the V 2 O 3 layer. Its role as a Lewis acid layer enables the sequestration of excess OH - ions, mitigate Cl - corrosion, and alkaline earth salt precipitation. Our catalyst protection strategy by using V 2 O 3 presents a promising and cost-effective approach for large-scale sustainable green hydrogen production.

Electrocatalytic high-throughput seawater electrolysis for hydrogen production is a promising green energy technology that offers possibilities for environmental and energy sustainability. However, large-scale application is limited by the complex composition of seawater, high concentration of Cl - leading to competing reaction, and severe corrosion of electrode materials. In recent years, extensive research has been conducted to address these challenges. Metal nitrides (MNs) with excellent chemical stability and catalytic properties have emerged as ideal electrocatalyst candidates. This review presents the electrode reactions and basic parameters of the seawater splitting process, and summarizes the types and selection principles of conductive substrates with critical analysis of the design principles for seawater electrocatalysts. The focus is on discussing the properties, synthesis, and design strategies of MN-based electrocatalysts. Finally, we provide an outlook for the future development of MNs in the high-throughput seawater electrolysis field and highlight key issues that require further research and optimization.