Search

In this study, a simple potassium hydroxide (KOH) post-treatment was applied to increase the catalytic performance of γ-MnOOH in the carbonylation of n-BuNH2 with CO2 by the hydrothermal method. The catalytic activity of γ-MnOOH was significantly boosted and the degree of enhancement is directly related to the add amount of KOH, i.e. K(6.7)-γ-MnOOH > K(6.9)-γ-MnOOH > K(6.0)-γ-MnOOH > γ-MnOOH, in which the catalytic activity of K(6.7)-γ-MnOOH with n(KOH):n(γ-MnOOH) = 6.7 showed the greatest lift with the conversion of n-BuNH2 and the N,N′-dibutylurea yield from 48.81% and 47.85% for pristine γ-MnOOH up to 75.26% and 74.53% for K(6.7)-γ-MnOOH under 5.0 MPa at 160 °C for 4 h, respectively. XRD, SEM, FT-IR, BET, ESR, TG-DSC and XPS were utilized for additional characterization in order to explore the mechanism behind the increased catalytic activity of the as-synthesised K(x)-γ-MnOOH (x = 6.0, 6.7, and 6.9). And it is found that after KOH treatment that the surface oxygen vacancy concentration of γ-MnOOH is significantly enhanced by a surface hydroxyl dehydration of γ-MnOOH and thus promoted an increase of the catalytic activities of K(x)-γ-MnOOH (x = 6.0, 6.7 and 6.9) in the carbonylation of BuNH2 with CO2. This method provides a simple, economical, and effective way to enhance the catalytic activities of metal oxides in CO2 capture and utilization. [ABSTRACT FROM AUTHOR]

Common precursors for carbon materials typically include petroleum‐based polymers or MOF materials. However, these materials often encounter challenges such as metal aggregation, high cost, and metals leaching. In this work, a novel of approach lignin‐metal supramolecular framework complex (MSF@Lignin) is introduced. These complexes are formed through oxidative ammonolysis of lignin (OAL) to synthesize a nitrogen‐doped carbon‐encapsulated CoRu nanocatalyst (CoRu@OALC) via in situ carbonization. CoRu@OALC exhibited exceptional performance in both HER (90 mV) and OER (200 mV) at the current density of 10 mA cm−2, with an overall water splitting voltage of 1.5 V and outstanding stability under high density. During the pyrolysis process, metal became encapsulated by lignin‐derived carbon, occurring within the temperature range of 600–700 °C. In the catalytic process, active sites are primarily located within the defects in lignin‐derived carbon, showcasing a unique "self‐healing" phenomenon within the carbon layer. Oxygen‐containing intermediates (*OH, *O, and *OOH) facilitated the reconstruction of defects on the carbon layer, while the hydrogen‐containing intermediates (*H) contributed to the reappearance of a defect‐rich structure. [ABSTRACT FROM AUTHOR]

In the current 5G vehicle network system, there are security issues such as wireless intrusion, privacy leakage, and remote control. To address these challenges, an improved lightweight anonymous authentication key negotiation scheme based on certificate-less aggregate signatures is proposed and its security and efficiency are analyzed. The result shows that the scheme can offer security attributes including anonymity, traceability, and revocability, as well as effective identity authentication, and it can resist forgery attacks, man-in-the-middle attacks, tampering attacks, and smart card loss attacks. Moreover, compared with similar schemes, it possesses superior security and more efficient computational efficiency and less communication overhead, thereby being more appropriate for high-speed, large-capacity, low-latency, and resource-constrained 5G vehicle network application scenarios. [ABSTRACT FROM AUTHOR]

The utilization of plant polyphenols as catalyst carriers holds promise for environmentally friendly catalysis. However, challenges such as the inhomogeneous distribution of organic ligands often hinder their effectiveness. In this study, lignin–metal supramolecular framework were formed through ionic coordination self-assembly, achieved by oxidative ammonolysis modified lignin. The specific spatial domain-limiting effect of lignin–metal supramolecular framework ensures the dispersion and stability of catalyst active sites. Carbon-coated trimetallic catalysts (Ru–FeNi@OALC) derived from lignin–metal supramolecules exhibit promising performance, with low overpotentials for the oxygen evolution reaction (OER, η10 = 290 mV) and the hydrogen evolution reaction (HER, η10 = 52 mV), surpassing commercial noble metal catalysts. Additionally, these catalysts demonstrate long-lasting water-splitting performance, highlighting their potential for sustainable catalytic reactions. Molecular simulations and DFT theoretical calculations elucidate the feasibility of lignin oxidative ammonolysis modification and reveal the coordination mechanism. Furthermore, the abundant defects and disorder in the coordination polymer-derived carbon materials optimize electron transfer processes and accelerate reaction kinetics. This construction strategy towards designable polyphenol–metal supramolecular framework presents a promising avenue for the green synthesis of a variety of metal/carbon composite catalysts, contributing to sustainable catalysis and environmental protection. [ABSTRACT FROM AUTHOR]