The d-orbital coupling modulation of CuNi alloy for acetonitrile electrochemical reduction and in-situ hydrogenation behavior characterization

Electrochemical reduction of acetonitrile to ethylamine with a high selectivity is a novel approach to manufacture valuable primary amines which are important raw material in organic chemical industry. However, the poor ethylamine Faradic efficiency(FE_(ethylamine)) and catalyst stability at the high current density prohibit this method from being practically used. Herein, CuNi alloy ultrafine-nano-particles based on the d-orbital coupling modulation were synthesized through the electrodeposition and their catalytic performance towards acetonitrile reduction reaction(ACNRR) has been systematically studied. The highest FE_(ethylamine)(97%) is achieved with the current density of-114 mA cm^(-2). For practical application, the current density can reach-602.8 mA cm^(-2) with 82.8% FE_(ethylamine)maintained. With the appearance of other organics which co-exist with acetonitrile in the SOHIO process, CuNi can also hydrogenate acetonitrile in it with more than 80% FE_(ethylamine). Our in-situ spectroscopy analysis and DFT calculations towards the acetonitrile hydrogenation behavior reveal that the evenly dispersed Ni in Cu modulates the dband so as to endow CuNi with the better acetonitrile adsorption, milder binding energy with the reaction intermediates, smaller barrier for *CH_3CH_2NH_2 desorption and higher ability for H_2O dissociation to provide *H.

Acoustic Emission Monitoring and Microscopic Investigation of Cracks in ERCuNi Cladding

A corrosion resistant CuNi cladding was deposited on SM45C (equivalent to AISI1045) substrate by DC inverse arc welding. During the welding process, a three channel acoustic emission (AE) monitoring system was applied to detect the crack signals generating from both the cladding process and after cladding. Characteristics of the welding crack signal and noise signal had been analyzed systematically. Based on the record time of the signal, the solidification crack and delayed crack were distinguished. By two-dimensional AE source location, the crack position was located, and then investigated by scanning electron microscopy (SEM). Results showed that the AE system could detect the welding crack with high sensitivity and the two-dimensional source location could accurately determine the crack position. Microstructures of the cladding and heat affected zone (HAZ) were examined. Dendrites in the cladding and coarse grains in the HAZ were found.

Precisely Composition Controlled Synthesis of Cu0.5Ni0.5 Alloy with Optimum Catalytic Activity

Alloys based on non-noble metals could be the next generation of high-performance catalysts for many chemical reactions. However, precisely composition controlled synthesis of non-noble alloys remains a significant challenge. In this work, we report a simple synthesis of Cu_（0.5）Ni_（0.5） alloys without any component segregation. Its success relies on the use of Cu–Ni oxalate precursors, which are chelated in the proximity by oxalate ligands. One of the attractive features for the oxalate routes of catalyst preparation is that no classical support material is needed. The actual component ratios of the obtained Cu_（0.5）Ni_（0.5） alloy are consistent with the initial ratio. Cu_（0.5）Ni_（0.5） alloy shows a higher catalytic activity than pure Cu and Ni catalysts in the reduction of p-nitrophenol（4-NP） to p-aminophenol（4-AP） by sodium borohydride（NaBH4） in an aqueous solution, and the performance depends strongly on the strong interaction between Cu and Ni. The findings reported here are highly helpful to understand the relationship between the synergistic effects in alloys and their catalytic performance, and therefore could provide appropriate strategies to obtain desirable catalysts with improved activity in various catalytic applications.

Theoretical investigations on hydroxyl carbon precursor fueled growth of graphene on transition metal substrates

Transition metal catalyzed chemical vapor deposition (CVD) is considered as the most promising approach to synthesize highquality graphene films, and low-temperature growth of defect-free graphene films is long-term challenged because of the high energy barrier for precursor dissociation and graphitization. Reducing the growth temperature can also bring advantages on wrinkle-free graphene films owing to the minimized thermal expansion coefficient mismatch. This work focuses on density functional theory (DFT) calculations of the carbon source precursor with hydroxyl group, especially CH_(3)OH, on low-temperature CVD growth of graphene on Cu and CuNi substrate. We calculated all the possible cleavage paths for CH_(3)OH on transition metal substrates. The results show that, firstly, the cleavage barriers of CH_(3)OH on transition metal substrates are slightly lower than those of CH_(4), and once CO appears, it is difficult to break the C-O bond. Secondly, the CO promotes a better formation and retention of perfect rings in the early stage of graphene nucleation and reduces the edge growth barriers. Thirdly, these deoxidation barriers of CO are reduced after CO participates in graphene edge growth. This paper provides a strategy for the lowtemperature growth of wrinkles-free graphene on transition metal substrates using CH_(3)OH.