Role of Sodium Ion on TiO₂ Photocatalyst: Influencing Crystallographic Properties or Serving as the Recombination Center of Charge Carriers?

There have been continuing debates about the role of Na⁺ on TiO₂ photocatalyst in the past decades. Most researchers accepted that Na⁺ served as the recombination center of photogenerated electrons and holes. Nevertheless, other opinions also existed, such as Na⁺ increased the crystallite size of TiO₂, Na⁺ hampered the crystallization of anatase TiO₂, and Na⁺ promoted the formation of brookite TiO₂ or titanate sodium. In this research, we have systematically investigated the role of Na⁺ during the fabrication of TiO₂ film and powder through the sol–gel method and studied the influences of crystallinity and the content of Na⁺ on the photocatalytic activities of TiO₂ film and powder. It has been found that the existence of Na⁺ in TiO₂ film and powder should influence their crystallographic properties, in detail, inhibiting the crystallization and growth of anatase phase in TiO₂ film and powder, promoting the formation of brookite phase in TiO₂ film, and increasing the transformation temperature of anatase to rutile phase in TiO₂ powder. Even though the existence of Na⁺ forms the Ti–O–Na bond on the surface of TiO₂, however, the widely adopted hypothesis of Na⁺ serving as the recombination center of photogenerated electrons and holes is not correct

Easy Way To Create Stepped Surface: A Thought from Oriented Attachment

Easy Way To Create Stepped Surface: A Thought from Oriented Attachmen

Image_4_Integrated transcriptomic and metabolomic analyses revealed the molecular mechanism of terpenoid formation for salicylic acid resistance in Pulsatilla chinensis callus.tif

As a kind of traditional Chinese medicine, Pulsatilla chinensis (Bunge) Regel is well known for its anti-inflammation and anti-cancer activities, which are attributed to its active components including total saponins and monomers. To clarify the synthesis and metabolism mechanisms of class components in callus terpenes of P. chinensis, a certain concentration of salicylic acid (SA) hormone elicitor was added to the callus before being analysed by transcriptomic and metabolomic techniques. Results showed that the content of Pulsatilla saponin B4 in the callus suspension culture was significantly increased up to 1.99% with the addition of SA. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the differentially expressed genes were mainly enriched in 122 metabolic pathways, such as terpenoid metabolism-related pathways: terpenoid skeleton synthesis pathway, monoterpenoid biosynthesis pathways, diterpenoid biosynthesis pathways, and ubiquinone and other terpenoid-quinone biosynthesis pathways. A total of 31 differentially accumulated metabolites were obtained from four differential groups. Amongst 21 kinds of known chemical components in P. chinensis, deoxyloganic acid was the only monoterpenoid; the others are triterpenoids. In summary, this study found that SA elicitors can affect the metabolic changes of terpenoids in P. chinensis callus, which provided a basis for analysing the genetic regulation of terpenoid components of leucons.</p

Comparison of Sedimentary PAHs in the Rivers of Ammer (Germany) and Liangtan (China): Differences between Early- and Newly-Industrialized Countries

As a proxy to trace the impact of anthropogenic activity, sedimentary polycyclic aromatic hydrocarbons (PAHs) are compared between the early industrialized and newly industrialized countries of Germany and China, respectively. Surface sediment samples in the Ammer River of Germany and the Liangtan River of China were collected to compare concentration levels, distribution patterns, and diagnostic plots of sedimentary PAHs. Total concentrations of 16 PAHs in Ammer sediments were significantly higher by a factor of ∼4.5 than those in Liangtan. This contrast agrees with an extensive literature survey of PAH levels found in Chinese versus European sediments. Distribution patterns of PAHs were similar across sites in the Ammer River, whereas they were highly varied in the Liangtan River. Pyrogenic sources dominated in both cases. Strong correlations of the sum of 16 PAHs and PAH groups with TOC contents in the Liangtan River may indicate coemission of PAHs and TOC. Poor correlations of PAHs with TOC in the Ammer River indicate that other factors exert stronger influences. Sedimentary PAHs in the Ammer River are primarily attributed to input of diffuse sources or legacy pollution, while sediments in the Liangtan River are probably affected by ongoing point source emissions. Providing further evidence of a more prolonged anthropogenic influence are the elevated black carbon fractions in sedimentary TOC in the Ammer compared to the Liangtan. This implies that the Liangtan River, like others in newly industrialized regions, still has a chance to avoid legacy pollution of sediment which is widespread in the Ammer River and other European waterways

Facile Synthesis of Mesoporous and Thin-Walled Ni–Co Sulfide Nanotubes as Efficient Electrocatalysts for Oxygen Evolution Reaction

Development of high-performance and inexpensive electrocatalysts for oxygen evolution reaction (OER) is of important significance for sustainable energy conversion technologies. In this work, mesoporous Co and Ni–Co sulfide nanotubes with ultrathin nanowalls are designed and fabricated by a facile and template-free solvothermal method. The obtained CoS_1.097 nanotubes can be used as an OER electrocatalyst, and the incorporation of Ni into the CoS_1.097 lattice could further enhance the catalytic activity of the catalysts. The best-performing Ni_0.13­Co_0.87S_1.097 nanotubes exhibit high performance for OER with a small overpotential of 316 mV to achieve a current density of 10 mA cm^–2 and excellent stability, which outperform those of commercial IrO₂ and most of the studied Co-based OER catalysts. Our work demonstrates a new strategy to design highly efficient non-previous-metal OER electrocatalysts with unique structures and can be extended to other transition-metal-based systems