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211.
The construction of highly active, durable, and cost-effective catalysts is urgently needed for green hydrogen production. Herein, catalysts consisting of high-density Pt (24 atoms nm−2) and Ir (32 atoms nm−2) single atoms anchored on Co(OH)2 were constructed by a facile one-step approach. Remarkably, Pt1/Co(OH)2 and Ir1/Co(OH)2 only required 4 and 178 mV at 10 mA cm−2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. Moreover, the assembled Pt1/Co(OH)2//Ir1/Co(OH)2 system showed mass activity of 4.9 A mgnoble metal−1 at 2.0 V in an alkaline water electrolyzer, which is 316.1 times higher than that of Pt/C//IrO2. Mechanistic studies revealed that reconstructed Ir−O6 single atoms and remodeled Pt triple-atom sites enhanced the occupancy of Ir−O bonding orbitals and improved the occupation of Pt−H antibonding orbital, respectively, contributing to the formation of the O−O bond and the desorption of hydrogen. This one-step approach was also generalized to fabricate other 20 single-atom catalysts.  相似文献   
212.
The design of heterogeneous catalysts is necessarily surface-focused, generally achieved via optimization of adsorption energy and microkinetic modelling. A prerequisite is to ensure the adsorption energy is physically meaningful is the stable existence of the conceived active-site structure on the surface. The development of improved understanding of the catalyst surface, however, is challenging practically because of the complex nature of dynamic surface formation and evolution under in-situ reactions. We propose therefore data-driven machine-learning (ML) approaches as a solution. In this Minireview we summarize recent progress in using machine-learning to search and predict (meta)stable structures, assist operando simulation under reaction conditions and micro-environments, and critically analyze experimental characterization data. We conclude that ML will become the new norm to lower costs associated with discovery and design of optimal heterogeneous catalysts.  相似文献   
213.
Decarbonizing N2 conversion is particularly challenging, but essential for sustainable development of industry and agriculture. Herein, we achieve electrocatalytic activation/reduction of N2 on X/Fe−N−C (X=Pd, Ir and Pt) dual-atom catalysts under ambient condition. We provide solid experimental evidence that local hydrogen radical (H*) generated on the X site of the X/Fe−N−C catalysts can participate in the activation/reduction of N2 adsorbed on the Fe site. More importantly, we reveal that the reactivity of X/Fe−N−C catalysts for N2 activation/reduction can be well adjusted by the activity of H* generated on the X site, i.e., the interaction between the X−H bond. Specifically, X/Fe−N−C catalyst with the weakest X−H bonding exhibits the highest H* activity, which is beneficial to the subsequent cleavage of X−H bond for N2 hydrogenation. With the most active H*, the Pd/Fe dual-atom site promotes the turnover frequency of N2 reduction by up to 10 times compared with the pristine Fe site.  相似文献   
214.
The regeneration of the reduced form cofactor NAD(P)H is essential for the extra-cellular application of bio-reduction, which necessitates not only the development of efficient artificial NAD(P)H regeneration catalytic system but also its well compatibility with the cascade enzymatic reduction system. In this work, we reported the preparation of a metal nanoparticle (NP) and metal complex integrated core-shell nanoreactor for H2-driven NAD(P)H regeneration through the immobilization of a Rh complex on Ni/TiO2 surface via a bipyridine contained 3D porous organic polymer (POP). In comparison with the corresponding single component metal NPs and the immobilized Rh complex, the integrated catalyst presented simultaneously enhanced activity and selectivity in NAD(P)H regeneration thanks to the rapid spillover of activated H species from metal NPs to Rh complex. In addition, the size-sieving effect of POP precluded the direct interaction of enzyme and Rh complex confined in the pores, enabling the success coupling of core-shell nanoreactor and aldehyde ketone reductase (AKR) for chemoenzymatic reduction of acetophenone to (R)-1-phenylethan-1-ol. This work provides a strategy for the rational manipulation of multicomponent cooperation catalysis.  相似文献   
215.
Multi-walled carbon nanotubes (MWNTs) were modified by oxyfluorination treatment at several different temperatures of 20, 100, 200, and 300 °C. The changes of surface properties of oxyfluorinated MWNTs were investigated using X-ray photoelectron spectroscopy (XPS) method. As a result, it was found that surface fluorine contents were varied with changing an oxyfluorination temperature and showed a maximum value at 100 °C. By changing the treatment temperature in the process of oxyfluorination for carbon supports, the surface characteristics of MWNTs had been modified, resulting that the size and loading content of deposited Pt on the modified carbon supports could be changed. Consequently, Pt deposited MWNTs that were treated at 100 °C (Pt/100-MWNTs) showed the best electroactivity among samples. The enhanced electroactivity was dependent on the higher surface area of electrochemical reaction for metal catalyst, which was related to the particle size and the morphology of the deposited particle catalysts.  相似文献   
216.
<正>Highly active calcium chloride(CaCl_2) doped Zn-Co~Ⅲdouble metal-cyanide(Ca-DMC) catalysts were firstly reported.Ca-DMCs presented a very higher polymer yield(54 kg polymer/g catalyst) at relative low temperature(80-115℃) toward ringopening polymerization(ROP) of propylene oxide(PO) than did DMC catalysts without modification.  相似文献   
217.
<正>A novel ferrite composite using rice husk as substrate has been prepared via high temperature treatment under nitrogen atmosphere.The rice husk substrate consists of porous activated carbon and silica,where spinel ferrite particles with average diameter of 59 nm are distributed.The surface area of the composite is greater than 170 m~2 g~(-1) and the bulk density is less than 0.6 g cm~(-3).Inert atmosphere is indispensable for the synthesis of pure ferrite composites,while different preparation temperatures of above 600℃result in composites with similar structures and morphologies.Due to the presence of ferrite particles,this novel composite shows enhanced adsorption ability for acid orangeⅡ.  相似文献   
218.
合成了一种新型三元铁基合金催化剂Fe(Pd)P, 通过X射线粉末衍射(XRD)、等离子体发射(ICP)和扫描电子显微镜(SEM)等手段对催化剂进行了表征. 将其应用于催化PH_3分解的实验, 初步探讨了催化反应条件. 结果表明: 三元铁基合金催化剂Fe(Pd)P具有很好的热稳定性及很高的催化活性, 使用此催化剂在420 ℃, 磷化氢的实际分解率可高达90%以上.  相似文献   
219.
The polymeric ligand (resin) was synthesized by condensation of 2-hydroxy-4-ethoxybenzophenone with 1,2-propylene glycol in presence of polyphosphoric acid as a catalyst at 150 °C for 10 h. The resin and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, Fourier transform infrared spectroscopy (FTIR), NMR and thermogravimetric analyses. Morphological Study of resin and polychelates were carried out by scanning electron microscope (SEM). The number average molecular weight was determined using vapor pressure osmometry (VPO) method. Antimicrobial activity of polychelates and catalytic activity of selected polychelates in organic synthesis have been studied. It was observed that, polychelates were found efficient catalysts and effective antimicrobial agents.  相似文献   
220.

The oxalato complex of a polyoxomolybdovanadate, K6[Mo6V2O24(C2O4)2]·6H2O has been obtained by reaction of potassium molybdate, ammonium vanadate and tartaric or ascorbic acid. Such conversion of dicarboxylate into oxalate ions indicates the catalytic role of molybdenum. Complexes of analogous composition also were obtained in the reactions of MoO3, V2O5 and potassium oxalate, or M 2CO3 (M = Rb, Cs) and oxalic acid. The centrosymmetrical molybdovanadate anion [Mo6V2O24(C2O4)2]6- consists of six MoO6 and two VO6 edge-sharing octahedra to give the n -[Mo6O26]4- structure. All complexes were characterized by powder and single crystal X-ray analyses, ESR and IR spectra and TG and DSC measurements.  相似文献   
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