pyridinic n
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2022 ◽  
Author(s):  
Yong Cao ◽  
Qi zhang ◽  
Mi Peng ◽  
Zirui Gao ◽  
Wendi Guo ◽  
...  

Abstract Development of biomimetic catalytic systems that can imitate or even surpass natural enzymes remains an ongoing challenge 1–3. This is particularly true in the context of accessing non-natural reactions by bioinspired approaches, which offer intriguing possibilities for benign and affordable chemical synthesis 4. Exploiting the untapped potential of inorganic solids by translating complex knowledge in (bio)molecular-based systems may constitute a potentially useful strategy for such purpose 5, but efforts to capitalize on the minimum catalytic unit of a versatile solid matrix have been largely unsuccessful. Here, we show how an all-inorganic biomimetic system bearing robust nitrogen-neighboured single cobalt site/pyridinic-N site (Co-N4/Py-N) pairs can act cooperatively as an oxidase mimic, which renders an engaged coupling of oxygen (O2) reduction with synthetically beneficial chemical transformations. By developing this broadly applicable platform, the scalable synthesis of greater than 100 industrially and pharmaceutically appealing O-silylated compounds via the unprecedented aerobic oxidation of hydrosilane under ambient conditions is demonstrated. Moreover, this heterogeneous oxidase mimic also offers potential for expanding the catalytic scope of enzymatic synthesis. We anticipate that the strategy demonstrated here will pave a new avenue for understanding the underlying nature of redox enzymes and open up a new class of material systems for artificial biomimetics.


Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7619
Author(s):  
Fernando Montejo-Alvaro ◽  
Diego González-Quijano ◽  
Jorge A. Valmont-Pineda ◽  
Hugo Rojas-Chávez ◽  
José M. Juárez-García ◽  
...  

To reduce the CO2 concentration in the atmosphere, its conversion to different value-added chemicals plays a very important role. Nevertheless, the stable nature of this molecule limits its conversion. Therefore, the design of highly efficient and selective catalysts for the conversion of CO2 to value-added chemicals is required. Hence, in this work, the CO2 adsorption on Pt4-xCux (x = 0–4) sub-nanoclusters deposited on pyridinic N-doped graphene (PNG) was studied using the density functional theory. First, the stability of Pt4-xCux (x = 0–4) sub-nanoclusters supported on PNG was analyzed. Subsequently, the CO2 adsorption on Pt4-xCux (x = 0–4) sub-nanoclusters deposited on PNG was computed. According to the binding energies of the Pt4-xCux (x = 0–4) sub-nanoclusters on PNG, it was observed that PNG is a good material to stabilize the Pt4-xCux (x = 0–4) sub-nanoclusters. In addition, charge transfer occurred from Pt4-xCux (x = 0–4) sub-nanoclusters to the PNG. When the CO2 molecule was adsorbed on the Pt4-xCux (x = 0–4) sub-nanoclusters supported on the PNG, the CO2 underwent a bond length elongation and variations in what bending angle is concerned. In addition, the charge transfer from Pt4-xCux (x = 0–4) sub-nanoclusters supported on PNG to the CO2 molecule was observed, which suggests the activation of the CO2 molecule. These results proved that Pt4-xCux (x = 0–4) sub-nanoclusters supported on PNG are adequate candidates for CO2 adsorption and activation.


NANO ◽  
2021 ◽  
Author(s):  
Yanfei Zhu ◽  
Baichen Wang ◽  
Wei Li ◽  
Yu Gao

In this paper, a new hydrogen peroxide electrochemical sensor based on the synergistic modification of nitrogen-doped porous carbon (NPC) and carbon nanohybrid aerogel (CNA) is proposed. NPC has been successfully synthesized from porous polyacrylonitrile (PAN) precursor by pre-oxidation to obtain adequate pyridinic-N, which contributes to enhance the electrocatalytic activity. Simultaneously, CNA has been also prepared by self-assembly in a hydrothermal environment without any interference followed by vacuum freeze drying. The final products were characterized by diversiform techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). The results showed that the NPC with 23.18% pyridinic-N exhibited well-defined and interconnected three-dimensional (3D) porous microstructure and CNA which encapsulates [Formula: see text]-Fe2O3 particles was obtained. The sensor fabricated by NPC and CNA delivered a wide linear range from 60[Formula: see text][Formula: see text]M to 1680[Formula: see text][Formula: see text]M ([Formula: see text]) and 1680[Formula: see text][Formula: see text]M to 3335[Formula: see text][Formula: see text]M ([Formula: see text]) with sensitivities of 3.98[Formula: see text][Formula: see text]A mM[Formula: see text] and 5.56[Formula: see text][Formula: see text]A mM[Formula: see text], respectively. Furthermore, the obtained sensor showed low detection limit (4.478[Formula: see text][Formula: see text]M, [Formula: see text]/[Formula: see text]), good selectivity and repeatability, rapid response and satisfying practicability.


Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2727
Author(s):  
Gil-Ryeong Park ◽  
Seung Geun Jo ◽  
Anuraj Varyambath ◽  
Jeonghyun Kim ◽  
Jung Woo Lee

It is imperative to design an inexpensive, active, and durable electrocatalyst in oxygen reduction reaction (ORR) to replace carbon black supported Pt (Pt/CB). In this work, we synthesized Pd4.7Ru nanoparticles on nitrogen-doped reduced graphene oxide (Pd4.7Ru NPs/NrGO) by a facile microwave-assisted method. Nitrogen atoms were introduced into the graphene by thermal reduction with NH3 gas and several nitrogen atoms, such as pyrrolic, graphitic, and pyridinic N, found by X-ray photoelectron spectroscopy. Pyridinic nitrogen atoms acted as efficient particle anchoring sites, making strong bonding with Pd4.7Ru NPs. Additionally, carbon atoms bonding with pyridinic N facilitated the adsorption of O2 as Lewis bases. The uniformly distributed ~2.4 nm of Pd4.7Ru NPs on the NrGO was confirmed by transmission electron microscopy. The optimal composition between Pd and Ru is 4.7:1, reaching −6.33 mA/cm2 at 0.3 VRHE for the best ORR activity among all measured catalysts. Furthermore, accelerated degradation test by electrochemical measurements proved its high durability, maintaining its initial current density up to 98.3% at 0.3 VRHE and 93.7% at 0.75 VRHE, whereas other catalysts remained below 90% at all potentials. These outcomes are considered that the doped nitrogen atoms bond with the NPs stably, and their electron-rich states facilitate the interaction with the reactants on the surface. In conclusion, the catalyst can be applied to the fuel cell system, overcoming the high cost, activity, and durability issues.


Author(s):  
Chao Ye ◽  
Jieqiong Shan ◽  
Dongliang Chao ◽  
Pei Liang ◽  
Yan Jiao ◽  
...  

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