Latest ArticlesHydrogen evolution reaction (HER) catalytic electrodes under actual working conditions show interesting mass transfer behaviors at solid (electrode)/liquid (electrolyte)/gas (hydrogen) three-phase interfaces. These behaviors are essential for forming a continuous and effective physical contact region between the electrolyte and the electrode and require further detailed understanding. Here, a case study on 1T-2H phase molybdenum disulfide (MoS2)/carbon fiber paper (CFP) catalytic electrodes is performed. Rapid gas-liquid mass transfer at the interface for enhancing the working area stability and capillarity for increasing the electrode working area is found. The real scenario, wherein the energy utilization efficiency of the as-prepared non-noble metal catalytic electrode exceeds that of the noble metal catalytic electrode, is disclosed. Specifically, a fluid dynamics model is developed to investigate the behavior mechanism of hydrogen bubbles from generation to desorption on the catalytic electrode surface with different hydrophilic and hydrophobic properties. These new insights and theoretical evidence on the non-negligible three-phase interface behaviors will identify opportunities and motivate future research in high-efficiency, stability, and low-cost HER catalytic electrode development.
Hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) have been considered as two critical processes in the field of electrocatalytic water-splitting for hydrogen production and fuel cells. However, the sluggish reaction kinetics of HER and ORR required efficient electrocatalyst such as Pt to promote such process. Transition metal phosphides (TMPs) exhibit great potential to replace noble metal electrocatalysts to accelerate HER and ORR due to their high activity and easy availability. Herein, a highly-efficient bifunctional CoP electrocatalyst for HER and ORR, featuring a unique core-shell structure decorated on nitrogen-doped carbon matrix was designed and constructed via etching a cobalt-based zeolitic imidazolate framework (ZIF-67) with phytic acid (PA) followed by pyrolysis treatment (PA-ZIF-67–900). Experimental results revealed that the pure-phase single-crystalline CoP exhibited outstanding electrocatalytic performance in HER and ORR, superior to Co(PO3)2 in PA-ZIF-67–700, hybrid phase of Co(PO3)2 and CoP in PA-ZIF-67–800 and Co2P-doped CoP in PA-ZIF-67–1000. To reach the current density of 10 mA/cm2 the as-synthesized CoP required an overpotential of 120 mV for HER in 1 mol/L KOH and half-wave potential of 0.85 V in O2-saturated 0.1 mol/L KOH. This work present new clue for construction of efficient and bifunctional electrocatalyst in the field of energy conversion and storage
Selective hydrogenation of cinnamaldehyde (CAL) toward cinnamyl alcohol (COL) is an extremely important and challenging reaction. Herein, a series of PtxFey-Al2O3 bimetallic catalysts with varied Pt to Fe ratios were prepared by incipient wetness impregnation method. The introduction of Fe significantly modifies the electronic and surface properties of Pt, which clearly enhances the C=O hydrogenation selectivity. Among all the catalysts, Pt3Fe-Al2O3 displays the best catalytic performance and the conversion of CAL is 96.6% with 77.2% selectivity of COL within 1 h. In addition, Pt3Fe-Al2O3 had excellent reusability with 76% COL selectivity after five runs of the recycle process. Further characterization of the fresh, used and cycled catalysts revealed that the structure and electronic state of the synthesized PtxFey-Al2O3 are unchanged after hydrogenation reaction. The identical-location transmission electron microscopy (IL-TEM) results revealed that the interaction between the nanoparticles and the supports was strong and the catalyst was relatively stable.
The development of effective uranium-removal techniques is of great significance to the environment and human health. In this work, a double potential step technique (DPST) was applied to remove U(VI) from uranium-containing wastewater using a carbon felt electrode modified by graphene oxide/phytic acid composite (GO-PA@CF). The application of DPST can inhibit water splitting and prevent GO-PA from adsorbing other interfering ions in wastewater. The GO-PA composite can effectively accelerate the electrochemical reduction rate of U(VI), which significantly improved the electrochemical deposition rate of uranium oxide. As a result, the maximum removal efficiency and maximum removal capacity of GO-PA@CF electrode reached 98.7% and 1149.3 mg/g, respectively. The removal efficiency remained 97.2% after five cycles of reuse. Moreover, the removal efficiency of GO-PA@CF electrode can reach more than 70% in simulated wastewater.
Aqueous phase synthesized ternary I–III–VI2 Quantum dots (QDs) are getting more and more attention in biology researches, for their good biocompatibility and easy-to-adjust fluorescence properties. However, the quantum yield (QY) of these aqueous phase synthesized QDs are often pretty low, which seriously hindered their further applications in this field. In general, the ripening of the QDs helps to enhance their QY, closely related to the ripening temperature. But it is still hard to precisely control the fluorescence performance of the QDs products, due to the difficulties in precise temperature control and cumbersome temperature adjusting operations in batch reactors. Here we proposed an integrated droplet microfluidic chip for the automated and successive AgInS2 QDs synthesis and ripening, with both temperatures controlled independently, precisely but easily. Taking advantage of the space-time transformation of the droplet microfluidic chips, the suitable temperature combination for AgInS2 QDs synthesis and ripening was studied, and the high-performance AgInS2 QDs were obtained. In addition, the reason for the decrease of QY of AgInS2 QDs at higher ripening temperature was also explored.
RNA molecules contain diverse modifications that display important functions in a variety of physiological and pathological processes. So far over 150 chemical modifications have been characterized to be present in various RNA species, such as in messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). Previous studies revealed that certain RNA modifications were correlated to specific human diseases, indicating RNA modifications could serve as the potential indicator of human diseases. However, systemic investigation of the alteration of RNA modifications in different RNA species of carcinoma tissues are still lacked. Herein, we carried out the comprehensive profiling and evaluation of the alteration of RNA modifications in thyroid carcinoma by liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS) analysis. The developed method allowed us to simultaneously detect 48 different types of RNA modifications. Using this method, we detected 10, 15, 14, and 25 modifications in mRNA, 18S rRNA, 28S rRNA and small RNA (< 200 nt), respectively. Compared to the normal tissues, we revealed a total of 14 RNA modification exhibited significant increase and 2 RNA modifications showed significant decrease in thyroid carcinoma tissues. Our study provided the first comprehensive profile as well as the alteration of modifications in different RNA species in thyroid carcinoma and matched tumor-adjacent normal tissues. The altered pattern RNA modifications may serve as the indicator of thyroid carcinoma. Moreover, this study may promote the in-depth understanding of the regulatory roles of RNA modifications in thyroid carcinoma.
5-Hydroxymethylcytosine (5hmC), an intermediate product of DNA demethylation, is important for the regulation of gene expression during development and even tumorigenesis. The challenges associated with determination of 5hmC level include its extremely low abundance and high structural similarity with other cytosine derivatives, which resulted in sophisticated treatment with large amount of sample input. Herein, we developed a primer-initiated strand displacement amplification (PISDA) strategy to quantify the global 5hmC in genomic DNA from mammalian tissues with high sensitivity/selectivity, low input and simple operation. This sensitive fluorescence method is based on 5hmC-specific glucosylation, primer ligation and DNA amplification. After the primer was labeled on 5hmC site, DNA polymerase and nicking enzyme will repeatedly act on each primer, causing a significant increase of fluorescence signal to magnify the minor difference of 5hmC content from other cytosine derivatives. This method enables highly sensitive analysis of 5hmC with a detection limit of 0.003% in DNA (13.6 fmol, S/N = 3) from sample input of only 150 ng, which takes less than 15 min for determination. Further determination of 5hmC in different tissues not only confirms the widespread presence of 5hmC but also indicates its significant variation in different tissues and ages. Importantly, this PISDA strategy exhibits distinct advantages of bisulfite-free treatment, mild conditions and simple operation without the involvement of either expensive equipment or large amount of DNA sample. This method can be easily performed in almost all research and medical laboratories, and would provide a promising prospect to detect global 5hmC in mammalian tissues.
Lanthanide-doped upconversion nanoparticles (Ln-UCNPs) are a new type of nanomaterials with excellent fluorescence properties, which are well applied in fluorescent biosensing. Herein we developed a multifunctional probe based on the surface engineering of core-shell structure UCNPs with polyacrylic acid (PAA). The developed PAA/UCNPs probe could be highly selective to detect and respond to Cu2+ at different pH. Cu2+ could easily combine with the carboxylate anion of PAA to quench the fluorescence of UCNPs. Therefore, we creatively proposed a fluorescent array sensor (PAA/UCNPs-Cu2+), in which the same material acted as the sensing element by coupled with pH regulation for pattern recognition of 5 thiols. It could also easily identify the chiral enantiomer of cystine (L-Cys-and D-Cys), and distinguish their mixed samples with different concentrations, and more importantly, it could be combined with urine samples to detect actual level of homocysteine (Hcys) to provide a new solution for judging whether the human body suffers from homocystinuria.
The construction of rich phase interfaces to increase active reaction area in hybrid materials is an excellent strategy to improve electrochemical performance. Under this guideline, MIL-101@OX-metal organic framework (MOF) is constructed by the "MOF on MOF" method, then converts to MIL-101@NiFe-layered double hydroxides (LDH) by in situ transformation in alkaline solution. MIL-101@NiFe-LDH shows excellent electrochemical water oxidation performance. It needs only an overpotential of 215 mV to drive 10 mA/cm2 of oxygen evolution reaction (OER), which is less than that of NiFe-LDH, MIL-101. In addition, MIL-101@NiFe-LDH has the smallest Tafel slope (55.1 mV/dec) compared with NiFe-LDH (61.1 mV/dec), MIL-101 (150.8 mV/dec). The excellent water oxidation activity is due to the high phase interfaces derived from high specific surface area of MOF. This work offers an alternative method for making MOF/LDH heterostructures with an optimized phase interfaces and provides new insights for OER.
Water pollution has become a serious problem owing to the development of society. Photocatalysis is a promising approach to remove various pollutants in water, such as organic pollutants and antibiotic resistance bacteria. Meanwhile, the design of heterojunction between two semiconductors is an effective path to improve photocatalytic properties due to its potential in improving separation and transfer of photoinduced carriers. In this study, Nb2O5/g-C3N4 (NO/CN) composite materials were prepared through a one-step heating method. Characterizations confirmed successful preparation of NO/CN heterojunction structure and better optical properties than pure g-C3N4 and Nb2O5. NO/CN composite materials showed excellent photocatalytic efficiency for Escherichia coli (E. coli) inactivation (95%) compared with the pure Nb2O5 (10%) and g-C3N4 (77%). Meanwhile, NO/CN exhibited better organic pollutants removal (RhB for 94%, methyl orange (MO) for 15% and methylene blue (MB) for 87%) under visible light, which is likely owing to the heterojunction structure between g-C3N4 and Nb2O5 that leads to the good separation of photogenerated electron-hole pair. Free radical scavenging and electron spin resonance (ESR) experiments demonstrated that superoxide radicals (•O2−) and holes (h+) were the dominant radicals. Therefore, the NO/CN was proposed to be a promising material for effective disinfection and removal of organic contaminants in water treatment.
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