Yanling Qiu,Wenbin Xu,Pengfei Yao,Qiong Zheng,Huamin Zhang,Xianfeng Li
Graphical A helping hand : Copper electrodes derived from Cu 2 O with predominant (111) facets are synthesized by cetyltrimethylammonium bromide-assisted preparation. The optimized electrode shows a high faradaic efficiency of 90 % for formic acid obtained by electrochemical reduction of CO 2 at −2.0 V (vs.SCE), which surpasses most reported Cu electrodes. The electrochemical reduction of CO 2 (ERC) to valuable chemicals has attracted extensive attention. However, the relatively low selectivity and efficiency of the reaction remain challenges. In this study, Cu electrodes derived from Cu 2 O with predominant (111) facets are synthesized by cetyltrimethylammonium bromide-assisted preparation. The optimized electrode shows a high faradaic efficiency of 90 % for HCOOH obtained by ERC at −2.0 V (vs.SCE), which surpasses most reported Cu electrodes. Based on a comprehensive analysis of the relationship between the catalytic activity and the thickness of the Cu 2 O layer, the catalytic activity of the unit active site on the Cu 2 O-derived Cu electrodes is found to be higher than that on the blank Cu electrode. DFT calculations indicate that OCHO* would be produced preferentially over *COOH in the presence of cetyltrimethylammonium bromide (CTAB). This deduction is verified by testing of the effects of CTAB and KBr addition on HCOO − selectivity.
Bi 2 O 3 /Dy 2 O 3 nanoflakes with triclinic Bi 2 O 3 and cubic Dy 2 O 3 phases were synthesized by a hexadecyl trimethyl ammonium bromide (CTAB)-assisted hydrothermal route. The Bi 2 O 3 /Dy 2 O 3 nanoflakes were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, electron microscopy and electrochemical impedance spectroscopy. The size of the Bi 2 O 3 /Dy 2 O 3 nanoflakes with curled surface is about 2 μm and thickness is about 25 nm. X-ray photoelectron spectroscopy confirms the chemical composition of the Bi 2 O 3 /Dy 2 O 3 nanoflakes. The formation process of the Bi 2 O 3 /Dy 2 O 3 nanoflakes was investigated by controlling the CTAB concentration, reaction temperature and reaction time. The formation of the Bi 2 O 3 /Dy 2 O 3 nanoflakes depends on CTAB. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy demonstrate good electro-catalytic activity of the Bi 2 O 3 /Dy 2 O 3 nanoflakes towards L-cysteine with a pair of quasi-reversible CV peaks at +0.01 V and –0.68 V, respectively. Bi 2 O 3 /Dy 2 O 3 nanoflakes modified electrode detects L-cysteine linearly over a concentration ranging from 0.001 to 2 mM with a detection limit of 0.32 μM. The proposed nanocomposites modified electrode possesses good reproducibility and stability which can be used as a promising candidate for L-cysteine detection.
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