Nearly 100% selective and visible-light-driven methane conversion to formaldehyde via. single-atom Cu and Wδ+

Direct solar-driven methane (CH4) reforming is highly desirable but challenging, particularly to achieve a value-added product with high selectivity. Here, we identify a synergistic ensemble effect of atomically dispersed copper (Cu) species and partially reduced tungsten (Wδ+), stabilised over an oxygen-vacancy-rich WO3, which enables exceptional photocatalytic CH4 conversion to formaldehyde (HCHO) under visible light, leading to nearly 100% selectivity, a very high yield of 4979.0 μmol·g-1 within 2 h, and the normalised mass activity of 8.5 × 106 μmol·g-1Cu·h-1 of HCHO at ambient temperature. In-situ EPR and XPS analyses indicate that the Cu species serve as the electron acceptor, promoting the photo-induced electron transfer from the conduction band to O2, generating reactive •OOH radicals. In parallel, the adjacent Wδ+ species act as the hole acceptor and the preferred adsorption and activation site of H2O to produce hydroxyl radicals (•OH), and thus activate CH4 to methyl radicals (•CH3). The synergy of the adjacent dual active sites boosts the overall efficiency and selectivity of the conversion process

Efficient hole abstraction for highly selective oxidative coupling of methane by Au-sputtered TiO2 photocatalysts

Photocatalytic oxidative coupling of methane (OCM) produces C2 molecules that can be used as building blocks for synthesis of fuels and chemicals. However, the yield rate and the selectivity of C2 products are still moderate due to the stable nature of methane molecules. Here we develop a Au nanocluster-loaded TiO2 photocatalyst by a sputtering approach, achieving a high methane conversion rate of 1.1 mmol h−1, C2 selectivity of ~90% and apparent quantum efficiency of 10.3 ± 0.6%. The high C2/C2+ yield rate is on the same order of magnitude as the benchmark thermal catalysts in OCM processes operated at high temperature (>680 °C). Au nanoparticles are shown to prolong TiO2 photoelectron lifetimes by a factor of 66 for O2 reduction, together with Au acting as a hole acceptor and catalytic centre to promote methane adsorption, C–H activation and C–C coupling. This work underscores the importance of multifunctional co-catalysts and mechanistic understanding to improve photocatalytic OCM

Synergy of Pd atoms and oxygen vacancies on In₂O₃ for methane conversion under visible light

Methane (CH4) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues regarding both conversion and selectivity. Herein, under visible irradiation (420 nm), the synergy of palladium (Pd) atom cocatalyst and oxygen vacancies (OVs) on In2O3 nanorods enables superior photocatalytic CH4 activation by O2. The optimized catalyst reaches ca. 100 μmol h-1 of C1 oxygenates, with a selectivity of primary products (CH3OH and CH3OOH) up to 82.5%. Mechanism investigation elucidates that such superior photocatalysis is induced by the dedicated function of Pd single atoms and oxygen vacancies on boosting hole and electron transfer, respectively. O2 is proven to be the only oxygen source for CH3OH production, while H2O acts as the promoter for efficient CH4 activation through ·OH production and facilitates product desorption as indicated by DFT modeling. This work thus provides new understandings on simultaneous regulation of both activity and selectivity by the synergy of single atom cocatalysts and oxygen vacancies

PdCu nanoalloy decorated photocatalysts for efficient and selective oxidative coupling of methane in flow reactors

Methane activation by photocatalysis is one of the promising sustainable technologies for chemical synthesis. However, the current efficiency and stability of the process are moderate. Herein, a PdCu nanoalloy (~2.3 nm) was decorated on TiO2, which works for the efficient, stable, and selective photocatalytic oxidative coupling of methane at room temperature. A high methane conversion rate of 2480 μmol g-1 h-1 to C2 with an apparent quantum efficiency of ~8.4% has been achieved. More importantly, the photocatalyst exhibits the turnover frequency and turnover number of 116 h-1 and 12,642 with respect to PdCu, representing a record among all the photocatalytic processes (λ > 300 nm) operated at room temperature, together with a long stability of over 112 hours. The nanoalloy works as a hole acceptor, in which Pd softens and weakens C-H bond in methane and Cu decreases the adsorption energy of C2 products, leading to the high efficiency and long-time stability

The role of zinc in the adaptive evolution of polar phytoplankton

Zinc is an essential trace metal for oceanic primary producers with the highest concentrations in polar oceans. However, its role in the biological functioning and adaptive evolution of polar phytoplankton remains enigmatic. Here, we have applied a combination of evolutionary genomics, quantitative proteomics, co-expression analyses and cellular physiology to suggest that model polar phytoplankton species have a higher demand for zinc because of elevated cellular levels of zinc-binding proteins. We propose that adaptive expansion of regulatory zinc-finger protein families, co-expanded and co-expressed zinc-binding proteins families involved in photosynthesis and growth in these microalgal species and their natural communities were identified to be responsible for the higher zinc demand. The expression of their encoding genes in eukaryotic phytoplankton metatranscriptomes from pole-to-pole was identified to correlate not only with dissolved zinc concentrations in the upper ocean but also with temperature, suggesting that environmental conditions of polar oceans are responsible for an increased demand of zinc. These results suggest that zinc plays an important role in supporting photosynthetic growth in eukaryotic polar phytoplankton and that this has been critical for algal colonization of low-temperature polar oceans

Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques

Di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT) exhibits significant antitumor activity. However, the mechanism of its pharmacological interaction with human serum albumin (HSA) and DNA remains poorly understood. Here, we aimed to elucidate the interactions of Dp44mT with HSA and DNA using MTT assays, spectroscopic methods, and molecular docking analysis. Our results indicated that addition of HSA at a ratio of 1:1 did not alter the cytotoxicity of Dp44mT, but did affect the cytotoxicity of the Dp44mT-Cu complex. Data from fluorescence quenching and UV-VIS absorbance measurements demonstrated that Dp44mT could bind to HSA with a moderate affinity (Ka = approximately 104 M−1). CD spectra revealed that Dp44mT could slightly disrupt the secondary structure of HSA. Dp44mT could also interact with Ct-DNA, but had a moderate binding constant (KEB = approximately 104 M−1). Docking studies indicated that the IB site of HSA, but not the IIA and IIIA sites, could be favorable for Dp44mT and that binding of Dp44mT to HSA involved hydrogen bonds and hydrophobic force, consistent with thermodynamic results from spectral investigations. Thus, the moderate binding affinity of Dp44mT with HSA and DNA partially contributed to its antitumor activity and may be preferable in drug design approaches

Correction: Zhongjie Xu, et al. Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA using Molecular Docking and Spectroscopic Techniques. Int. J. Mol. Sci. 2016, 17, 1042

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Response to the Letter to the Editor by D. Richardson: Analysis of the Interaction of Dp44mT with Human Serum Albumin and Calf Thymus DNA Using Molecular Docking and Spectroscopic Techniques

This response refers to

Diversity and arsenic-tolerance potential of bacterial communities from soil and sediments along a gold tailing contamination gradient

Gold tailings often lead to the release of arsenic (As) contaminants into the surrounding environment. Microorganisms play an important role in the As cycle, whereas the effects of As on bacterial communities remain unclear. To reveal the effects of As on diversity and variation of bacterial communities and their As-tolerance potential, farmland soil and river sediment samples were collected according to distance from tailings in Dandong area of northeastern China. The bacterial communities were analyzed using high-throughput sequencing of 16S rRNA genes. The membrane transport proteins ArsB or ACR3 pump As(III) out of the cell to resist As toxicity. We studied the abundance and phylogeny of ArsB and ACR3 by using PCR-based clone libraries and Quantitative PCR. The bacterial community was divided into 10 phyla and 59 genera. It was indicated that the transformation from As (V) to As(III) process was predominant, which was coupled with denitrification. Both of ArsB and ACR3 likely evolved from different orders of Proteobacteria. The arsB gene seems to be more stable in bestowing the capability of bacteria to respond to the As concentration. Moreover, As with iron, manganese and total organic carbon also influenced the clustering relationships of samples and bacterial distribution.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author