Copper single-crystal reduction

Product Distribution in CO2 Reduction at a Series of Copper Single-Crystal Electrodes, Cu(S)-[w(100) x (111)] and Cu(S)-[w(lOO) X (110)]. Reprinted from Ref. 91, Copyright (2003) with Permission from Elsevier... 

Fig. 6. The decomposition of formic acid on different crystal faces of copper single crystal discs, after electropolishing and prolonged reduction of the discs in hydrogen at 400°C. The logarithm of reaction probability P is plotted as a function of 10s/T. O copper (111) face A-. copper (110) face copper (100) face. The dotted line refers to a result mentioned in Section III, A, 4. [According to A. J. Crocker and A. J. B. Robertson (37).]...

Hori, Y., I. Takahashi, O. Koga, and N. Hoshi (2002). Selective formation of C2 compounds from electrochemical reduction of CO2 at a series of copper single crystal electrodes. J. Phys. Chem. B 106, 15-17. 

At the same time, if a solid has strong initial plastic character (e.g., metal single crystal), the transition into a brittle state with reduced strength may not occur, even at low a. For example, liquid bismuth does not cause an embrittlement of copper single crystals. The grain boundaries in polycrystalline solids, while acting as a strengthening factor, can cause a reduction in plasticity due to the retardation of the dislocation movement. For this reason, for a polycrystalline solid, the reduction in 0 may be already sufficient for a transition to the brittle state to take place. Indeed, liquid bismuth is known to cause an anbrittlement of polycrystalline copper. 

Several reactions proceed competitively at copper electrodes, and the electrocatalytic activity for the individual reactions depends on the atomic configuration of the electrode surface. Thus fundamental study using single cry stal electrodes is relevant to reveal the unique electrocatalytic naUires of copper metal. Frese reported that CH4 formation in the electrochemical reduction of CO2 is favored in the order of Cu(lll). Cu(llO) and Cu(lOO). Later Hori et al. extensively studied the reaction with various series of Cu single crystal electrodes. ... 

FIG. 17 SECM chronoamperometric transients for the reduction of Cu2+ with a 25 /im diameter Pt UME positioned at distances of 2 (upper curve), 5, 10 /rm (lowest curve) from the (100) face of a copper sulfate pentahydrate single crystal. The initial solution conditions were 3.6 mol dm-3 H2S04 and saturated copper sulfate. In each case the potential was stepped from —0.2 to —0.65 V versus AgQRE. 

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