Experimental and theoretical investigation of high-entropy-alloy/support as a catalyst for reduction reactions

Control of chemical composition and incorporation of multiple metallic elements into a single metal nanoparticle(NP)in an alloyed or a phase-segregated state hold potential scientific merit;however,developing libraries of such structures using effective strategies is challenging owing to the thermodynamic immiscibility of repelling constituent metallic elements.Herein,we present a one-pot interfacial plasma-discharge-driven(IP-D)synthesis strategy for fabricating stable high-entropy-alloy(HEA)NPs exhibiting ultrasmall size on a porous support surface.Accordingly,an electric field was applied for 120 s to enhance the incorporation of multiple metallic elements(i.e.,CuAgFe,CuAgNi,and CuAgNiFe)into ally HEA-NPs.Further,NPs were attached to a porous magnesium oxide surface via rapid cooling.With solar light as the sole energy input,the CuAgNiFe catalyst was investigated as a reusable and sustainable material exhibiting excellent catalytic performance(100%conversion and 99% selectivity within1 min for a hydrogenation reaction)and consistent activity even after 20 cycles for a reduction reaction,considerably outperforming the majority of the conventional photocatalysts.Thus,the proposed strategy establishes a novel method for designing and synthesizing highly efficient and stable catalysts for the convertion of nitroarenes to anilines via chemical reduction.

Origin of the synergistic effects of bimetallic nanoparticles coupled with a metal oxide heterostructure for accelerating catalytic performance

Precisely tuning bicomponent intimacy during reactions by traditional methods remains a formidable challenge in the fabrication of highly active and stable catalysts because of the difficulty in constructing well-defined catalytic systems and the occurrence of agglomeration during assembly.To overcome these limitations,a PtRuPNiO@TiO_(x)catalyst on a Ti plate was prepared by ultrasound-assisted low-voltage plasma electrolysis.This method involves the oxidation of pure Ti metal and co-reduction of strong metals at 3000◦C,followed by sonochemical ultrasonication under ambient conditions in an aqueous solution.The intimacy of the bimetals in PtRuPNiO@TiOx is tuned,and the metal nanoparticles are uniformly distributed on the porous titania coating via strong metal-support interactions by leveraging the instantaneous high-energy input from the plasma discharge and ultrasonic irradiation.The intimacy of PtRuPNiO@TiO_(x)increases the electron density on the Pt surface.Consequently,the paired sites exhibit a high hydrogen evolution reaction activity(an overpotential of 220 mV at a current density of 10 mA cm^(−2)and Tafel slope of 186 mV dec^(−1)),excellent activity in the hydrogenation of 4-nitrophenol with a robust stability for up to 20 cycles,and the ability to contrast stated catalysts without ultrasonication and plasma electrolysis.This study facilitates industrially important reactions through synergistic chemical interactions.

Well-defined high entropy-metal nanoparticles:Detection of the multi-element particles by deep learning

Characterizing and control the chemical compositions of multi-element particles as single metal nanoparticles(mNPs) on the surfaces of catalytic metal oxide supports is challenging.This can be attributed to the heterogeneity and large size at the nanoscale,the poorly defined catalyst nanostructure,and thermodynamic immiscibility of the strongly repelling metallic elements.To address these challenges,an ultrasonic-assisted coincident electro-oxidation-reduction-precipitation(U-SEO-P) is presented to fabricate ultra-stable PtRuAgCoCuP NPs,which produces numerous active intermediates and induces strong metal-support interactions.To sort the active high-entropy mNPs,individual NPs are described on the support surface and the role of deep learning in understanding/predicting the features of PtRuAgCoCu@TiO_(x) catalysts is explained.Notably,this deep learning approach required minimal to no human input.The as-prepared PtRuAgCoCu@TiO_(x) catalysts can be used to catalyze various important chemical reactions,such as a high reduction conversion(100% in 30 s),with no loss of catalytic activity even after 20 cycles of nitroarene and ketone/aldehyde,which is several times higher than commercial Pt@TiO_(x) owing to individual PtRuAgCoCuP NPs on TiO_(x) surface.In this study,we present the "Totally Defined Catalysis" concept,which has enormous potential for the advancement of high-activity catalysts in the reduction of organic compounds.

Counter-balancing effects of Si on C partitioning and stacking fault energy of austenite in 10Mn quenching and partitioning steel

Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize austenite.When 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free counterpart.Moreover,the suppression of carbide formation promoted C partitioning into austenite as expected.However,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of austenite.As partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility level.This was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the deformation.The resulting strengthening effect compensated for the softening caused by martensite recovery.Consequently,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.