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Oxygen electroreduction (ORR) via a two-electron pathway is a promising alternative for hydrogen peroxide (H2O2) synthesis in small-scale applications. In this work, nitrogen and sulfur co-doped carbon coated zinc sulfide nanoparticles (ZnS@C) are synthesized using facile high-temperature annealing. In an alkaline electrolyte, the presence of ZnS suppresses the reduction of H2O2 during the ORR and contributes to high H2O2 selectivity (∼90%) over a wide potential range (0.40–0.80 V). Continuous generation of H2O2 is in turn achieved at an outstanding rate of 1.485 mol gcat.−1 h−1 with a faradaic efficiency of 93.7%. [ABSTRACT FROM AUTHOR]

In this paper, KIT-6 is used as a template to prepare ordered mesoporous materials WO3 and Au-loaded WO3 (Au–WO3). The pristine WO3 sensor and the Au–WO3 sensor are fabricated for the detection of 19 important gases, such as trimethylamine, formaldehyde and CS2. The results show that the Au–WO3 sensor has better selectivity and higher response to TMA. At a working temperature of 268 °C, the response (Ra/Rg) of the Au–WO3 sensor to 100 ppm of TMA is 41.56 and the response time is 1 s. In addition, the sensor has excellent response/recovery capabilities and stability. These high sensing performances are mainly attributed to the electronic and chemical sensitization of the noble metal Au and the presence of a high specific surface area supported by the mesoporous structure. Therefore, Au-doped mesoporous WO3 should be a promising material for a high performance TMA gas sensor. [ABSTRACT FROM AUTHOR]

To enable high-efficiency solar energy conversion, rational design and preparation of low cost and stable semiconductor photocatalysts with associated co-catalysts are desirable. However preparation of efficient catalytic systems remains a challenge. Here, N-doped TiO2/ternary nickel-zinc nitride (N–TiO2–Ni3ZnN) nanocomposites have been shown to be a multi-functional catalyst for photocatalytic reactions. The particle size of Ni3ZnN can be readily tuned using N–TiO2 nanospheres as the active support. Due to its high conductivity and Pt-like properties, Ni3ZnN promotes charge separation and transfer, as well as reaction kinetics. The material shows co-catalytic performance relevant for multiple reactions, demonstrating its multifunctionality. Density functional theory (DFT) based calculations confirm the intrinsic metallic properties of Ni3ZnN. N–TiO2–Ni3ZnN exhibits evidently improved photocatalytic performances as compared to N–TiO2 under visible light irradiation. [ABSTRACT FROM AUTHOR]

Fe-Doped NiO multi-shelled microspheres have been synthesized via a facile hydrothermal reaction. Various characterization techniques were introduced to investigate the structure and morphology of the as-prepared Fe-doped NiO multi-shelled microspheres. SEM and TEM observations showed that NiO microspheres are about 500 nm in diameter and with three shells. The Fe-doped NiO multi-shelled microspheres were investigated systematically as gas sensing materials for chemiresistive semiconductor-based gas sensors. The results showed that the 1.92 at% Fe-doped NiO (1.92Fe-NiO) multi-shelled microspheres exhibited enhanced gas sensing performance compared to the pure NiO multi-shelled microspheres. The gas response of 1.92Fe-NiO multi-shelled microspheres to 100 ppm butanol was 45.1 at 140 °C, which revealed a remarkable improvement over the pure NiO multi-shelled microspheres (6.80). The increased response of 1.92Fe-NiO multi-shelled microspheres may be attributed to the incorporation of Fe ions into NiO nanocrystals, which adjusted the carrier concentration and caused an increase in the oxygen species on the adsorbed surface. Therefore, the Fe-doped NiO multi-shelled microspheres should be a promising material for high performance butanol gas sensors. [ABSTRACT FROM AUTHOR]

One of the greatest challenges in the enhancement of the electrical properties of conductive mayenite [Ca24Al28O64]4+(4e−) (hereinafter C12A7:e−) is the design of a more suitable/simple synthesis strategy that can be employed to obtain the required properties such as excellent stable electrical conductivity, a high electron concentration, outstanding mobility, and an exceptionally large surface area. Therefore, to synthesize C12A7:e− in the metallic state, we proposed a facile, direct synthesis strategy based on an optimized sol–gel combustion method under a nitrogen gas environment using the low-cost precursors Ca(NO3)2·4H2O and Al(NO3)3·9H2O. Using this developed strategy, we successfully synthesized moderately conductive nanoscale C12A7:e− powder, but with unexpected carbon components (reduced graphene oxide (rGO) and/or graphene oxide (GO)). The synthesized C12A7:e− composite at room temperature has an electrical conductivity of about 21 S cm−1, a high electron concentration of approximately 1.5 × 1021 cm−3, and a maximum specific surface area of 265 m2 g−1. Probably, the synthesized rGO was coated on nanocage C12A7:e− particles. In general, the C12A7:e− electride is sensitive to the environment (especially to oxygen and moisture) and protected by an rGO coating on C12A7:e− particles, which also enhances the mobility and keeps the conductivity of C12A7:e− electride stable over a long period. Doped mayenite electride exhibits a conductivity that is strongly dependent on the substitution level. The conductivity of gallium-doped mayenite electride increases with the doping level and has a maximum value of 270 S cm−1, which for the first time has been reported for the stable C12A7:e− electride. In the case of Si-substituted calcium aluminate, the conductivity has a maximum value of 222 S cm−1 at room temperature. [ABSTRACT FROM AUTHOR]