银纳米晶对铒镱共掺的TeO2-WO3-La2O3微晶玻璃发光性能的影响

通过熔融退火的方法以及热处理技术制备得到含有Er₂WO₆，La₂WO₆晶体的TeO₂-WO₃-La₂O₃-Er₂O₃-Yb₂O₃微晶玻璃，该玻璃具有优异的上转换发光性能。结果表明，在含银纳米晶的碲酸盐微晶玻璃中，银纳米晶和微晶的析出情况与银纳米晶的引入方式和热处理温度有关。经过390℃下15 min的热处理后，AgCl和AgNO₃共掺的碲酸盐微晶玻璃比单掺AgCl或AgNO₃的碲酸盐微晶玻璃具有更高的发光强度。银纳米晶与微晶的引入可协同提高碲酸盐玻璃的上转换发光性。     

Polymer-precursor-derived (am-) SiC/TiC composites for resistive heaters in large volume multi-anvil high pressure/high-temperature apparatus

(Amorphous-)SiC/TiC composites for resistive tubular heaters in HP/HT experiments were obtained via a polymer-precursor process. A slurry consisting of a commercial SiC-precursor polymer (allylhydridopolycarbosilane, AHPCS) and TiC powder as conductive filler was applied to the inner walls of zirconia insulation tubes, using a centrifugation-casting method. Resistive coatings with homogeneous thickness of ～200 μm were obtained. The heaters were tested in octahedral multi-anvil assemblies at ～10 GPa with simultaneous recording of heating voltage and current. Up to a maximum temperature of ～1800°C they showed temperature vs. power characteristics reproducible from batch to batch, with resistance decreasing from 0.08 to 0.02 Ω during heating. Microstructural characterization using SEM/EDX was carried out on the recovered SiC/TiC composite material, as well as on pristine resistive heaters directly after coating and curing to 230°C, and after additional pyrolysis at 900°C in argon. In all cases, a stable composite microstructure of an interpenetrating network of TiC particles with either silicon carbide polymer precursor or an amorphous SiC phase were found. The composites were characterized by XRD and thermogravimetry. Further improvement of coating procedure and materials combination (precursor/filler/insulator substrate) may result in advanced coatings, operational well beyond 2000°C.     

Bi‐, Y‐Codoped TiO2 for Carbon Dioxide Photocatalytic Reduction to Formic Acid under Visible Light Irradiation

Bi‐ and Y‐codoped TiO₂ photocatalysts were synthesized through a sol‐gel method, and they were applied in the photocatalytic reduction of CO₂ to formic acid under visible light irradiation. The results revealed that, after doping Bi and Y, the surface area of TiO₂ was increased from 5.4 to 93.1 m²/g when the mole fractions of doping Bi and Y were 1.0% and 0.5%, respectively, and the lattice structures of the photocatalysts changed and the oxygen vacancies on the surface of the photocatalysts formed, which would act as the electron capture centers and slow down the recombination of photo‐induced electron and hole. The photocurrent spectra also proved that the photocatalysts had better electronic transmission capacities. The HCOOH yield in CO₂ photocatalytic reduction was 747.82 μmol/g_cat by using 1% Bi‐0.5% Y‐TiO₂ as a photocatalyst. The HCOOH yield was 1.17 times higher than that by using 1% Bi‐TiO₂, and 2.23 times higher than that by using pure TiO₂. Furthermore, the 1% Bi‐0.5% Y‐TiO₂ showed the highest apparent quantum efficiency (AQE) of 4.45%.     

Effects of acceptor–donor complexes on electronic structure properties in co-doped TiO2: A first-principles study

We theoretically investigate the doping effects induced by impurity complexes on the electronic structures of anatase TiO₂ based on the density functional theory. Mono-doping and co-doping effects are discussed separately. The results show that the impurity doping can make the band-edges shift. The induced defect levels in the band gaps by impurity doping reduce the band gap predominantly. The compensated acceptor–donor pairs in the co-doped TiO₂ will improve the photoelectrochemical activity. From the calculations, it is also found that (S+Zr)-co-doped TiO₂ has the ideal band gap and band edge, at the same time, the binding energy is higher than other systems, so (S+Zr)-co-doping in TiO₂ is more promise in photoelectrochemical experiments.     

Synergistic Effect of Boron Nitride and Carbon Domains in Boron Carbide Nitride Nanotube Supported Single-Atom Catalysts for Efficient Nitrogen Fixation

Developing the low-cost and efficient single-atom catalysts (SACs) for nitrogen reduction reaction (NRR) is of great importance while remains as a great challenge. The catalytic activity, selectivity and durability are all fundamentally related to the elaborate coordination environment of SACs. Using first-principles calculations, we investigated the SACs with single transition metal (TM) atom supported on defective boron carbide nitride nanotubes (BCNTs) as NRR electrocatalysts. Our results suggest that boron-vacancy defects on BCNTs can strongly immobilize TM atoms with large enough binding energy and high thermal/structural stability. Importantly, the synergistic effect of boron nitride (BN) and carbon domains comes up with the modifications of the charge polarization of single-TM-atom active site and the electronic properties of material, which has been proven to be the essential key to promote N₂ adsorption, activation, and reduction. Specifically, six SACs (namely V, Mn, Fe, Mo, Ru, and W atoms embedded into defective BCNTs) can be used as promising candidates for NRR electrocatalysts as their NRR activity is higher than the state-of-the art Ru(0001) catalyst. In particular, single Mo atom supported on defective BCNTs with large tube diameter possesses the highest NRR activity while suppressing the competitive hydrogen evolution reaction, with a low limiting potential of −0.62 V via associative distal path. This work suggests new opportunities for driving NH₃ production by carbon-based single-atom electrocatalysts under ambient conditions.