Electrocatalytic synthesis of C–N coupling compounds from CO2 and nitrogenous species

The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (Nos. 42277485, 21976141, 22272197, 22102184, 22102136, andU22A20392), the Natural Science Foundation of Hubei Province (2022CFB1001 and 2021CFA034), the Department of Education of Hubei Province (Q20221701 and Q20221704), and the Joint Fund of Yulin University and Dalian National Laboratory for Clean Energy (YLU-DNL Fund 2022008).The electrocatalytic synthesis of C–N coupling compounds from CO2 and nitrogenous species not only offers an effective avenue to achieve carbon neutrality and reduce environmental pollution, but also establishes a route to synthesize valuable chemicals, such as urea, amide, and amine. This innovative approach expands the application range and product categories beyond simple carbonaceous species in electrocatalytic CO2 reduction, which is becoming a rapidly advancing field. This review summarizes the research progress in electrocatalytic urea synthesis, using N2, NO2−, and NO3− as nitrogenous species, and explores emerging trends in the electrosynthesis of amide and amine from CO2 and nitrogen species. Additionally, the future opportunities in this field are highlighted, including electrosynthesis of amino acids and other compounds containing C–N bonds, anodic C–N coupling reactions beyond water oxidation, and the catalytic mechanism of corresponding reactions. This critical review also captures the insights aimed at accelerating the development of electrochemical C–N coupling reactions, confirming the superiority of this electrochemical method over the traditional techniques.publishersversionpublishe

Synthesis of Nitrogen and Phosphorus/Sulfur Co-Doped Carbon Xerogels for the Efficient Electrocatalytic Reduction of p-Nitrophenol

Carbon xerogels co-doped with nitrogen (N) and phosphorus (P) or sulfur (S) were synthesized and employed as catalysts for the electrocatalytic reduction of p-nitrophenol (p-NP). The materials were prepared by first synthesizing N-doped carbon xerogels (NDCX) via the pyrolysis of organic gels, and then introducing P or S atoms to the NDCX by a vapor deposition method. The materials were characterized by various measurements including X-ray diffraction, N2 physisorption, Transmission electron microscopy, Fourier Infrared spectrometer, and X-ray photoelectron spectra, which showed that N atoms were successfully doped to the carbon xerogels, and the co-doping of P or S atoms affected the existing status of N atoms. Cyclic voltammetry (CV) scanning manifested that the N and P co-doped materials, i.e., P-NDCX-1.0, was the most suitable catalyst for the reaction, showing an overpotential of −0.569 V (vs. Ag/AgCl) and a peak slop of 695.90 μA/V. The material was also stable in the reaction and only a 14 mV shift in the reduction peak overpotential was observed after running for 100 cycles

Research Progress on Graphitic Carbon Nitride/Metal Oxide Composites: Synthesis and Photocatalytic Applications

Although graphitic carbon nitride (g-C3N4) has been reported for several decades, it is still an active material at the present time owing to its amazing properties exhibited in many applications, including photocatalysis. With the rapid development of characterization techniques, in-depth exploration has been conducted to reveal and utilize the natural properties of g-C3N4 through modifications. Among these, the assembly of g-C3N4 with metal oxides is an effective strategy which can not only improve electron–hole separation efficiency by forming a polymer–inorganic heterojunction, but also compensate for the redox capabilities of g-C3N4 owing to the varied oxidation states of metal ions, enhancing its photocatalytic performance. Herein, we summarized the research progress on the synthesis of g-C3N4 and its coupling with single- or multiple-metal oxides, and its photocatalytic applications in energy production and environmental protection, including the splitting of water to hydrogen, the reduction of CO2 to valuable fuels, the degradation of organic pollutants and the disinfection of bacteria. At the end, challenges and prospects in the synthesis and photocatalytic application of g-C3N4-based composites are proposed and an outlook is given

TDCS-IDMA System for Cognitive Radio Networks With Cloud

With increasing demand of wireless radio spectrum, fixed spectrum assignment policy leads to spectrum scarcity worldwide. However, most portion of spectrum is inefficiently used, which urges the development of dynamic spectrum access techniques [1]. The concept of cognitive radio (CR) is proposed as a possible solution to solve the spectral congestion problem. It provides the capability to utilize spectrum bands more efficiently in an opportunistic manner without much interruptions to primary users [2]–[4]. In the cognitive radio networks (CRNs), sensors are used to detect the presence of licensed users and find spectrum holes for dynamic spectrum access. Traditional spectrum sensing is usually carried out by CR nodes. This procedure requires complex computation and sufficient storage space to download software packages

Intestinal flora altered and correlated with interleukin-2/4 in patients with primary immune thrombocytopenia

AbstractBackground Little is known about the changes and mechanisms of intestinal flora in primary immune thrombocytopenia (ITP) patients.Aim To explore the structural and functional differences of intestinal flora between ITP patients and healthy controls, and clarify the correlation between intestinal flora and Th1/Th2 imbalance.Methods Feces from ITP patients and healthy controls were studied by 16S rRNA and metagenomic techniques at phylum, genus, species or functional levels. Blood samples were collected for the detection of interleukin −2 (IL-2) and IL-4 concentrations.Results The following changes in ITP patients were found: a decrease of Bacteroidetes phylum, an increase of Proteobacteria phylum and alterations of ten genera and 1045 species. IL-2 and IL-4 were significantly correlated with six and five genera, respectively. Species of C. freundii, C. rodentium, and C. youngae were negatively correlated with bleeding scores, and S. infantis was positively related to platelet counts. Functionally, the intestinal flora of ITP patients changed mainly in terms of motility, chemotaxis, membrane transport, and metabolism.Conclusion The mechanism underlying functional and structural changes of intestinal flora in ITP patients may be related to inflammation and immunity, providing possibilities of probiotics or fecal transplants for ITP

Quad-Model Imaging-Guided High-Efficiency Phototherapy Based on Upconversion Nanoparticles and ZnFe₂O₄ Integrated Graphene Oxide

The strategy of diagnosis-to-therapy to realize the integration of imaging and high antitumor efficiency has become the most promising method. Light-induced therapeutic technologies have drawn considerable interest. However, the limited penetration depth of UV/vis excitation and relatively low efficiency are the main obstacles for its further clinic application. For this concern, we presented a facile method to anchor ultrasmall ZnFe₂O₄ nanoparticles and upconversion luminescence nanoparticles (UCNPs) on graphene oxide (GO) nanosheets (GO/ZnFe₂O₄/UCNPs, abbreviated as GZUC). To solve the penetration question, here we introduced Tm³⁺-doped UCNPs to convert the high-penetrated near-infrared (NIR) light into UV/vis photons to activate the photodynamic process. In this system, the dual phototherapy from GO and ZnFe₂O₄ has been realized upon NIR laser irradiation. Combined with the photodynamic therapy (PDT) based on Fenton reaction that ZnFe₂O₄ nanoparticles react with excessive H₂O₂ in tumor microenvironment to produce toxic hydroxyl radicals (·OH), an excellent anticancer efficiency has been achieved. Furthermore, 4-fold imaging including upconversion luminescence (UCL), computed tomography (CT), magnetic resonance imaging (MRI) and photoacoustic tomography (PAT) has been obtained due to its intrinsic properties, thereby successfully realizing diagnosis-monitored therapy. Our demonstration provided a feasible strategy to solve the main problems in current light-triggered theranostic

Bismuth Nanoparticles with “Light” Property Served as a Multifunctional Probe for X‑ray Computed Tomography and Fluorescence Imaging

The development of the advanced imaging probe holds the key to the achievement of target imaging and metastasis tracing. The bismuth based nanoprobe has been regarded as the most promising X-ray computed tomography probe due to its largest X-ray attenuation coefficient. Accordingly, the bismuth nanoparticles with controllable size distribution and light weight have been fabricated through a one pot synthesis strategy. The surface modification can be easily conducted with the polyethylene glycol to make the nanoparticles hydrosoluble and biocompatible. More importantly, the Bi nanoparticles can be excited by light to conduct excitation wavelength dependent emission in the visible (Vis) and near-infrared (NIR) region, which makes it possible to utilize it for fluorescence imaging. Under the detection of the multimode CT/fluorescence imaging, the long circulation time of the Bi nanoparticles and its specific accumulation at the liver and intestine can be visually displayed. The facile and large scale preparation method, unique luminescence property, and multimode imaging function endow the Bi nanoparticles with promising applications in clinical diagnosis

Yolk-Structured Upconversion Nanoparticles with Biodegradable Silica Shell for FRET Sensing of Drug Release and Imaging-Guided Chemotherapy

Silica related nanovehicles are being widely studied for bioapplication, while the use <i>in vivo</i> has been restricted due to the biodegradation reluctance. Herein, a facile Mn-doping method was used to endow the upconversion nanoparticles (UCNPs) with a biodegradable shell, simply by transforming mesoporous silica coated UCNPs (UCNPs@mSiO₂) to Mn-doped upconversion nanocapsules (Mn-UCNCs). The yolk-structured Mn-UCNCs have huge internal space, which is greatly beneficial for DOX (a chemotherapeutic agent) storage. Furthermore, the Mn-doped nanoshell is responsive to mild reductive and acidic tumor condition, which enables the biodegradation of the silica shell in tumor sites and further accelerates the breakup of Si–O–Si bonds within the silica framework. This tumor-sensitive degradation of the shell not only facilitates DOX release in the tumor location but also allows faster nanoparticle diffusion and deeper tumor penetration, thus realizing efficient particle distribution and improved chemotherapy. Moreover, the biodegradability-enhanced DOX release brings a rapid recovery to the total emission intensity and a drastic decline to the red/green (R/G) ratio, which can be used to sense the drug release extent. The MRI effect caused by Mn release coupled with the inherent MRI/CT/UCL imaging derived from the UCNPs (NaGdF₄:Yb,Er@NaGdF₄:Yb) under NIR irradiation endow the nanocarrier with superior multiple imaging functions. The high biocompatibility of PEGylated Mn-UCNCs was validated, and the excellent anticancer effectiveness of the DOX loaded nanosystem was also achieved