Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced. To create cold weld between A1 and Ag, mating surfaces were specially prepared and various rolling thickness reductions were ...Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced. To create cold weld between A1 and Ag, mating surfaces were specially prepared and various rolling thickness reductions were applied. The minimum critical thickness reduction to begin cold weld was specified as 70% which equals 0.1630 critical rolling shape factors. The bimetallic strips were treated by diffusion annealing at 400 ~C and various annealing time. The A1/Ag interface of strips was observed by scanning electron microscope to investigate the formation of hard and brittle probable phases. The effect of anneal time on diffusion distance and phase transformation was also analysed by EDS analysis and line scan. A diffusion region along the interface in the Ag side was observed and its width increased with prolonging annealing time. Some 8 phases were detected close to the interface after anneal treating for 3 h and 8 phase was thicker and more continuous by increasing annealing time. The microhardness measurement showed that in spite of formation of 8 phase due to diffusion annealing, the interface hardness was reduced.展开更多
NO adsorption on Ag/Pt（110）-（1×2） bimetallic surfaces at room temperature was investigated by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy. An une...NO adsorption on Ag/Pt（110）-（1×2） bimetallic surfaces at room temperature was investigated by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy. An unexpected formation of nitrite/nitrate surface species on Ag/Pt（110）-（1 ×2） bimetallic surfaces is observed, then decompose at elevated temperatures to form N2. However, such nitrite/nitrate surface species do not form on clean Pt（110） and Ag-Pt alloy surfaces upon NO exposure at room temperature. The formation of nitrite/nitrate surface species on Ag/Pt（110）-（1×2） bimetallic surfaces is attributed to high reactivity of highly coordination-unsaturated Ag clusters and the synergetic effect between Ag clusters and Pt substrate.展开更多
Cobalt-based nanomaterials have been intensively explored as one of the most promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. However, most of their performances are still inferior to state...Cobalt-based nanomaterials have been intensively explored as one of the most promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. However, most of their performances are still inferior to state-of-the-art precious metals especially for Ru and Ir.Herein, we apply a continuous ion exchange method and further hydrothermal treatment to synthesize the flake-like Ag-CoSO4 nanohybrids beginning from Co-BTC (BTC:benzene-1,3,5-tricarboxylic acid) metal-organic frameworks precursor. The catalyst exhibits superior OER performance under the alkaline electrolyte solution (a low overpotential of 282 mV at 10 mA/cm2 in 1 mol/L KOH), which is even better than RuO2 due to the improved conductivity and rapid electrons transfer process via introducing small amount of Ag. The existence of Ag in the hybrids is beneficial for increasing the Co(IV) concentration, thus promoting the *OOH intermediate formation process. Besides, due to the very low requirement of Ag content (lower than 1 atom%), the cost of the catalyst is also limited. This work provides a new insight for designing of inexpensive OER catalysts with high performance and low cost.展开更多
文摘Aluminum and silver strips were cold welded by rolling and a bimetallic strip was produced. To create cold weld between A1 and Ag, mating surfaces were specially prepared and various rolling thickness reductions were applied. The minimum critical thickness reduction to begin cold weld was specified as 70% which equals 0.1630 critical rolling shape factors. The bimetallic strips were treated by diffusion annealing at 400 ~C and various annealing time. The A1/Ag interface of strips was observed by scanning electron microscope to investigate the formation of hard and brittle probable phases. The effect of anneal time on diffusion distance and phase transformation was also analysed by EDS analysis and line scan. A diffusion region along the interface in the Ag side was observed and its width increased with prolonging annealing time. Some 8 phases were detected close to the interface after anneal treating for 3 h and 8 phase was thicker and more continuous by increasing annealing time. The microhardness measurement showed that in spite of formation of 8 phase due to diffusion annealing, the interface hardness was reduced.
基金This work was supported by the National Natural Science Foundation of China （No.20973161 and No.11079033）, the Ministry of Science and Technology of China （No.2010CB923302）, the Fundamental Research Funds for the Central Universities, and the MPG-CAS partner group program.
文摘NO adsorption on Ag/Pt（110）-（1×2） bimetallic surfaces at room temperature was investigated by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy. An unexpected formation of nitrite/nitrate surface species on Ag/Pt（110）-（1 ×2） bimetallic surfaces is observed, then decompose at elevated temperatures to form N2. However, such nitrite/nitrate surface species do not form on clean Pt（110） and Ag-Pt alloy surfaces upon NO exposure at room temperature. The formation of nitrite/nitrate surface species on Ag/Pt（110）-（1×2） bimetallic surfaces is attributed to high reactivity of highly coordination-unsaturated Ag clusters and the synergetic effect between Ag clusters and Pt substrate.
基金supported by the National Natural Science Foundation(No.21271163,No.1232211,No.21571168)the Fundamental Research Funds for the Central Universities(WK2060140021)the CAS/SAFEA International Partnership Program for Creative Research Teams and the Hefei Science Center CAS(2016HSC-IU011)
文摘Cobalt-based nanomaterials have been intensively explored as one of the most promising noble-metal-free oxygen evolution reaction (OER) electrocatalysts. However, most of their performances are still inferior to state-of-the-art precious metals especially for Ru and Ir.Herein, we apply a continuous ion exchange method and further hydrothermal treatment to synthesize the flake-like Ag-CoSO4 nanohybrids beginning from Co-BTC (BTC:benzene-1,3,5-tricarboxylic acid) metal-organic frameworks precursor. The catalyst exhibits superior OER performance under the alkaline electrolyte solution (a low overpotential of 282 mV at 10 mA/cm2 in 1 mol/L KOH), which is even better than RuO2 due to the improved conductivity and rapid electrons transfer process via introducing small amount of Ag. The existence of Ag in the hybrids is beneficial for increasing the Co(IV) concentration, thus promoting the *OOH intermediate formation process. Besides, due to the very low requirement of Ag content (lower than 1 atom%), the cost of the catalyst is also limited. This work provides a new insight for designing of inexpensive OER catalysts with high performance and low cost.
