Abstract The nitrogenous nucleophile electrooxidation reaction (NOR) plays a vital role in the degradation and transformation of available nitrogen. Focusing on the NOR mediated by the β‐Ni(OH) 2 electrode, we decipher the transformation mechanism of the nitrogenous nucleophile. For the two‐step NOR, proton‐coupled electron transfer (PCET) is the bridge between electrocatalytic dehydrogenation from β‐Ni(OH) 2 to β‐Ni(OH)O, and the spontaneous nucleophile dehydrogenative oxidation reaction. This theory can give a good explanation for hydrazine and primary amine oxidation reactions, but is insufficient for the urea oxidation reaction (UOR). Through operando tracing of bond rupture and formation processes during the UOR, as well as theoretical calculations, we propose a possible UOR mechanism whereby intramolecular coupling of the N−N bond, accompanied by PCET, hydration and rearrangement processes, results in high performance and ca. 100 % N 2 selectivity. These discoveries clarify the evolution of nitrogenous molecules during the NOR, and they elucidate fundamental aspects of electrocatalysis involving nitrogen‐containing species.
Abstract Efficient ethanol oxidation reaction (EOR) is challenging due to the multiple reaction steps required to accomplish full oxidation to CO 2 in fuel cells. High‐entropy materials with the adjustable composition and unique chemical structure provide a large configurational space for designing high‐performance electrocatalysts. Herein, a new class of structurally ordered PtRhFeNiCu high‐entropy intermetallics (HEIs) is developed as electrocatalyst, which exhibits excellent electrocatalytic activity and CO tolerance for EOR compared to high‐entropy alloys (HEAs) comprising of same elements. When the HEIs are used as anode catalysts to be assembled into a high‐temperature polybenzimidazole‐based direct ethanol fuel cell, the HEIs achieve a high power density of 47.50 mW/cm 2 , which is 2.97 times of Pt/C (16.0 mW/cm 2 ). Online gas chromatography measurements show that the developed HEIs have a stronger C–C bond‐breaking ability than corresponding HEAs and Pt/C catalysts, which is further verified by density functional theory (DFT) calculations. Moreover, DFT results indicate that HEIs possess higher stability and electrochemical activity for EOR than HEAs. These results demonstrate that the HEIs could provide a new platform to develop high‐performance electrocatalysts for broader applications.
Abstract As a probiotic, Weizmannia coagulans ( W. coagulans ) is often used in food and medicine to regulate intestinal flora and resist specific inflammation. In this study, the anti-acne efficacy and mechanism of YTCY extracellular proteins (YTCY-EPs) from a strain of W. coagulans are analyzed. The main components of YTCY-EPs, extracted and separated from the fermentation broth, are peptides ranging from 1.51–11.44 kDa, accounting for about 80%. Among the peptides identified by LC/MS-MS, YTCY A-F possess the properties of antimicrobial peptides, while YTCY 1–4 possess antioxidative properties. These peptides have a strong effect on Cutibacterium acnes ( C. acnes ) and significantly inhibit Staphylococcus aureus . The adhesion of YTCY-EPs has a 50% inhibition rate. It is found that YTCY-EPs possess strong antioxidant and anti-inflammatory properties, and can reduce the downstream TLR2/NF-κB and MAPKs/AP-1 pathways by regulating the nuclear translocation of NF-κB and AP-1 in vitro. The transcriptional expression of inflammatory cytokines, inflammatory chemokines, and matrix metalloproteinase genes is also regulated, thereby slowing the recruitment of inflammatory cells and the development of inflammation, and increasing keratinocyte mobility. YTCY-EPs can also effectively solve such problems as erythema, papules, cysts, skin lesions, hyperkeratinization, and desquamation caused by C. acnes in rabbit ears. Additionally, the treatment effectively improves the condition of wounds and inflammation. The results of this study prove that YTCY-EPs can be used as a potential anti-acne raw material in cosmetics.
Electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3 ) is a promising approach to NH3 synthesis. However, due to the lack of efficient electrocatalysts, the performance of electrocatalytic NO reduction reaction (NORR) is far from satisfactory. Herein, it is reported that an atomic copper-iron dual-site electrocatalyst bridged by an axial oxygen atom (OFeN6 Cu) is anchored on nitrogen-doped carbon (CuFe DS/NC) for NORR. The CuFe DS/NC can significantly enhance the electrocatalytic NH3 synthesis performance (Faraday efficiency, 90%; yield rate, 112.52 µmol cm-2 h-1 ) at -0.6 V versus RHE, which is dramatically higher than the corresponding Cu single-atom, Fe single-atom and all NORR single-atom catalysts in the literature so far. Moreover, an assembled proof-of-concept Zn-NO battery using CuFe DS/NC as the cathode outputs a power density of 2.30 mW cm-2 and an NH3 yield of 45.52 µg h-1 mgcat-1 . The theoretical calculation result indicates that bimetallic sites can promote electrocatalytic NORR by changing the rate-determining step and accelerating the protonation process. This work provides a flexible strategy for efficient sustainable NH3 synthesis.
The LiCl–KCl–CsCl eutectic salt is expected to be used as a melt medium for the pyrochemical process of spent fuels because of its low melting point properties that reduce the temperature resistance requirements of the equipment. In this work, the electrochemical behaviors of La(III), Ce(III), and Nd(III) ions in the LiCl–KCl–CsCl eutectic salt in the range of 563–683 K were investigated, and it was found that the difficulty of cathodic passivation was in the order of La(III) < Ce(III) < Nd(III). Cyclic voltammetry (CV) and chronopotentiometry (CP) methods were conducted to determine the diffusion coefficients of La(III), Ce(III), and Nd(III). The corresponding diffusion activation energies were also calculated. It was also found that the passivation phenomenon does not affect the equilibrium potentials of La(III), Ce(III), and Nd(III), so we determined the apparent electrode potentials of La(III) and Ce (III) in the range of 563–683 K and Nd(III) in the range of 623–683 K by the galvanostatic voltammetry (GV) method. Finally, Ce and Nd metals were successfully extracted by potentiostatic electrolysis at 563 K for 4 h.
The electrocatalytic C-N coupling for one-step urea synthesis under ambient conditions serves as the promising alternative to the traditional urea synthetic protocol. However, the hydrogenation of intermediate species hinders the efficient urea synthesis. Herein, the oxygen vacancy-enriched CeO2 was demonstrated as the efficient electrocatalyst with the stabilization of the crucial intermediate of *NO via inserting into vacant sites, which is conducive to the subsequent C-N coupling process rather than protonation, whereas the poor selectivity of C-N coupling with protonation was observed on the vacancy-deficient catalyst. The oxygen vacancy-mediated selective C-N coupling was distinguished and validated by the in situ sum frequency generation spectroscopy. The introduction of oxygen vacancies tailors the common catalyst carrier into an efficient electrocatalyst with a high urea yield rate of 943.6 mg h-1 g-1, superior than that of partial noble-metal-based electrocatalysts. This work provides novel insights into the catalyst design and developments of coupling systems.
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