Facile synthesis of Ni doped CoWO4 nanoarrays grown on nickel foam substrates for efficient urea oxidation

Urea electrolysis is a promising technology for hydrogen production, which can alleviate environmental pollution of urea-rich wastewater. It's worth noting that electrochemistry activity can be significantly improved by reasonably regulating the electron configuration around the active site for the doped materials. In this work, a series of well-tuned Ni doped CoWO₄ nanoarrays on Ni foam supports have been prepared through a typical hydrothermal approach for the first time. Moreover, the resulting Ni–CoWO₄-2 material significantly promotes urea oxidation performance with an applied potential of 1.35 V at 50 mA cm^?2, which is lower than that of water oxidation reaction (1.60 V). Density functional theory results suggest that the Ni doped CoWO₄ has larger urea adsorption energy compared with CoWO₄ and the CO(NH₂)₂ molecule is strongly adsorbed on surface of Ni doped CoWO₄, which is beneficial to accelerate the kinetics of the reaction and improve the electrocatalytic activity of the urea electrolysis.     

Effects of Sr2+ substitution on the crystal structure,Raman spectra,bond valence and microwave dielectric properties of Ba3-xSrx(VO4)2 solid solutions

The effects of Sr²⁺ substitution for Ba²⁺ on microwave dielectric properties and crystal structure of Ba_3-xSr_x(VO₄)₂ (0 ≤ x ≤ 3, BSVO) solid solution were investigated. Such Sr²⁺ substitution contributes to significant reduction in sintering temperature from 1400 °C to 1150 °C. Both permittivity (∑_r) and quality factor (Q × f) values decreased with increasing x value, which was determined to be related with the descending values of average polarizability and packing fraction, whereas the increase in τ_f value was explained by the decreased average VO bond length, A-site bond valence. BSVO ceramics possessed encouraging dielectric performances with ∑_r = 12.2–15.6 ± 0.1, Q × f = 44,340 - 62,000 ± 800 GHz, and τ_f = 24.5–64.5 ± 0.2 ppm/°C. Low-temperature sintering was manipulated by adding B₂O₃ as sintering additive for the representative Sr₃V₂O₈ (SVO) ceramic and only 1 wt.% B₂O₃ addition successfully contributed to a 21.7% decrease in sintering temperature to 900 °C, showing good chemical compatibility with silver electrodes, which render BSVO series and SVO ceramics potential candidates in multilayer electronic devices fabrication.     

Peripheral Nerve-Derived Stem Cell Spheroids Induce Functional Recovery and Repair after Spinal Cord Injury in Rodents

Stem cell therapy is one of the most promising candidate treatments for spinal cord injury. Research has shown optimistic results for this therapy, but clinical limitations remain, including poor viability, engraftment, and differentiation. Here, we isolated novel peripheral nerve-derived stem cells (PNSCs) from adult peripheral nerves with similar characteristics to neural-crest stem cells. These PNSCs expressed neural-crest specific markers and showed multilineage differentiation potential into Schwann cells, neuroglia, neurons, and mesodermal cells. In addition, PNSCs showed therapeutic potential by releasing the neurotrophic factors, including glial cell-line-derived neurotrophic factor, insulin-like growth factor, nerve growth factor, and neurotrophin-3. PNSC abilities were also enhanced by their development into spheroids which secreted neurotrophic factors several times more than non-spheroid PNSCs and expressed several types of extra cellular matrix. These features suggest that the potential for these PNSC spheroids can overcome their limitations. In an animal spinal cord injury (SCI) model, these PNSC spheroids induced functional recovery and neuronal regeneration. These PNSC spheroids also reduced the neuropathic pain which accompanies SCI after remyelination. These PNSC spheroids may represent a new therapeutic approach for patients suffering from SCI.     

Revamping SiO2 Spheres by Core–Shell Porosity Endowment to Construct a Mazelike Nanoreactor for Enhanced Catalysis in CO2 Hydrogenation to Methanol

Beyond the catalytic activity of nanocatalysts, the support with architectural design and explicit boundary could also promote the overall performance through improving the diffusion process, highlighting additional support for the morphology-dependent activity. To delineate this, herein, a novel mazelike-reactor framework, namely multi-voids mesoporous silica sphere (MVmSiO₂), is carved through a top-down approach by endowing core-shell porosity premade Stöber SiO₂ spheres. The precisely-engineered MVmSiO₂ with peripheral one-dimensional pores in the shell and interconnecting compartmented voids in the core region is simulated to prove combined hierarchical and structural superiority over its analogous counterparts. Supported with CuZn-based alloys, mazelike MVmSiO₂ nanoreactor experimentally demonstrated its expected workability in model gas-phase CO₂ hydrogenation reaction where enhanced CO₂ activity, good methanol yield, and more importantly, a prolonged stable performance are realized. While tuning the nanoreactor composition besides morphology optimization could further increase the catalytic performance, it is accentuated that the morphological architecture of support further boosts the reaction performance apart from comprehensive compositional optimization. In addition to the found morphological restraints and size-confinement effects imposed by MVmSiO₂, active sites of catalysts are also investigated by exploring the size difference of the confined CuZn alloy nanoparticles in CO₂ hydrogenation employing both in-situ experimental characterizations and density functional theory calculations.     

Heterostructured Co3O4/VO2 nanosheet array catalysts on carbon cloth for hydrogen evolution reaction

Developing highly efficient, low-cost, and robust water splitting hydrogen production catalysts is critical for hydrogen energy applications. This study presents the synthesis of Co₃O₄/VO₂ heterogeneous nanosheet structures on carbon cloth (Co₃O₄/VO₂/CC). The obtained Co₃O₄/VO₂/CC hybrid catalyst has a low overpotential of 108 mV at a current density of 10 mA cm^?2, a Tafel slope of 98 mV dec^?1, and high stability in 1.0 M KOH for 10 h. The experimental results and density functional theory (DFT) calculations results also show that Co₃O₄ coupled with VO₂ in Co₃O₄/VO₂/CC can optimize hydrogen adsorption energy and facilitate electron transport, thereby accelerating the catalytic kinetics for hydrogen evolution reaction (HER). This work also provided an alternative method to design and construct non-noble metal oxide-based catalysts for alkaline hydrogen production.     

Role of functionalized graphene quantum dots in hydrogen evolution reaction: A density functional theory study

Rapid advances in the field of catalysis require a microscopic understanding of the catalytic mechanisms. However, in recent times, experimental insights in this field have fallen short of expectations. Furthermore, experimental searches of novel catalytic materials are expensive and time-consuming, with no guarantees of success. As a result, density functional theory (DFT) can be quite advantageous in advancing this field because of the microscopic insights it provides and thus can guide experimental searches of novel catalysts. Several recent works have demonstrated that low-dimensional materials can be very efficient catalysts. Graphene quantum dots (GQDs) have gained much attention in past years due to their unique properties like low toxicity, chemical inertness, biocompatibility, crystallinity, etc. These properties of GQDs which are due to quantum confinement and edge effects facilitate their applications in various fields like sensing, photoelectronics, catalysis, and many more. Furthermore, the properties of GQDs can be enhanced by doping and functionalization. In order to understand the effects of functionalization by oxygen and boron based groups on the catalytic properties relevant to the hydrogen-evolution reaction (HER), we perform a systematic study of GQDs functionalized with the oxygen (O), borinic acid (BC₂O), and boronic acid (BCO₂). All calculations that included geometry optimization, electronic and adsorption mechanism, were carried out using the Gaussian16 package, employing the hybrid functional B3LYP, and the basis set 6-31G(d,p). With the variation in functionalization groups in GQDs, we observe significant changes in their electronic properties. The adsorption energy E_ads of hydrogen over O-GQD, BC₂O-GQD, and BCO₂-GQD is ?0.059 eV, ?0.031 eV and ?0.032 eV respectively. Accordingly, Gibbs free energy (ΔG) of hydrogen adsorption is extraordinarily near the ideal value (0 eV) for all the three types of functionalized GQDs. Thus, the present work suggests pathways for experimental realization of low-cost and multifunctional GQDs based catalysts for clean and renewable hydrogen energy production.     

Precooked sorghum flour as proper vehicle of ACE-I and DPP-IV inhibitory sorghum peptides

Sorghum flour was heat treated for producing an instant dispersion ingredient. The precooked sorghum flour was added with ACE-I and DPP-IV inhibitory sorghum peptides (3.0 g peptide 100 g⁻¹). The product was reconstituted in water, and peptide bioaccessibility was evaluated by equilibrium dialysis method after simulated gastrointestinal digestion. Total peptide dialysability of precooked sorghum flour added with sorghum peptides was higher than those obtained for precooked sorghum flour (315.9 ± 14.8 vs. 45.2 ± 5.6 µmol, respectively) (P < 0.05). The ACE-I and DPP-IV-IC₅₀ values of the bioaccessible peptides from the bioactive product were lower than those obtained for precooked sorghum flour ingredient (1.04 ± 0.12 vs. 1.82 ± 0.09 and 0.86 ± 0.02 vs. 2.12 ± 0.08 mg protein mL⁻¹, for ACE-I and DPP-IV, respectively) indicating a higher activity. Precooked sorghum flour was a good vehicle since it did not affect the bioaccessibility of ACE-I and DPP-IV inhibitory peptides provided by sorghum protein hydrolysate.     

钚及其化合物表面腐蚀的研究进展

为了解掌握钚（Pu）及其化合物表面氧化腐蚀机理和探索能够有效缓解钚材料氧化腐蚀的环境体系，对国内外开展钚及其化合物表面化学的研究进行了综述，加深了对钚及其化合物在空气中的腐蚀行为的认识；对H₂、O₂、CO、CO₂等活性气体和Xe等稀有气体在钚及其化合物不同表面的吸附行为进行了对比分析，得到一些有益的结论。研究表明，Pu与各种活性气体和稀有气体的相互作用中伴随着电荷的转移，作用机理主要是气体原子分子的不同杂化轨道和Pu7s、Pu6p、Pu6d、Pu5f等杂化轨道相互作用生成了新的化学键，从而导致了相关反应和现象的产生。本研究还从改善研究方法、开展不同相的钚原子的不同表面吸附行为研究和探索防护钚材料氧化腐蚀新体系3个方面对钚及其化合物表面腐蚀研究工作进行了展望。     

Density functional theory study of the copper phthalocyanine based metal−organic frameworks as the highly active electrocatalysts for the oxygen reduction

Recently, the copper phthalocyanine based 2D conjugated MOFs have been demonstrated that it can efficiently catalyze the oxygen reduction reaction (ORR) experimentally. Herein, the inherent properties and ORR mechanism of PcCu-O₈-M (M = Fe, Co, Ni, Cu) containing two potential active sites (M–O₄ and Cu–N₄ sites) are investigated by density functional theory methods. The binding energy of oxygen-containing intermediates on PcCu-O₈-M indicates that the binding strength of 1OOH, 1O, and 1OH at the M–O₄ site is more moderate than that at the Cu–N₄ site. For all studied sites, their potential-determining steps are the step of O₂ → 1OOH except for the Ni–O₄ site of PcCu-O₈-Ni (1OH → H₂O). Among all sites of PcCu-O₈-M, the Fe–O₄ and Co–O₄ sites have excellent ORR activity with the overpotentials of 0.46 and 0.49 V, respectively, and the Cu–N₄ site of PcCu-O₈-Co possesses the relatively high ORR activity with the overpotential of 0.79 V. It can be concluded that compared with the Cu–N₄ site, the M–O₄ site plays major role for each PcCu-O₈-M during the ORR process. Moreover, the charge analysis of PcCu-O₈-Co suggests that the ORR activities of the Co–O₄ and Cu–N₄ sites are mainly originated from metal atoms (Co atom and Cu atom) as well as the O and N atoms (O and N-1) coordinated with metal atoms. In addition, PcCu-O₈-Co has high poisoning-tolerance ability to NO, NH₃, CO, SO₂, and H₂S.