Rational Design and Synthesis of SnOx Electrocatalysts with Coralline Structure for Highly Improved Aqueous CO2 Reduction to Formate
Rational Design and Synthesis of SnOx Electrocatalysts with Coralline Structure for Highly Improved Aqueous CO2 Reduction to Formate
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DOI：
10.1002/celc.201600290
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发表时间：
2016-10-01
期刊：
影响因子：
4
通讯作者：
Zhang, Jiujun
中科院分区：
文献类型：
--
作者：
Li, Yanan;Qiao, Jinli;Zhang, Jiujun
采用简单的水热自组装方法合成了几种具有新型珊瑚结构的氧化锡复合材料（SnOx）。然后用催化剂制备SnOx/GDL（气体扩散层）电极，用于CO2电还原在0.5m KHCO3水溶液中形成甲酸。系统研究了水热合成温度(T)/时间（δ T）和SnOx纳米催化剂中Sn的价态等因素对催化剂形貌和生成甲酸酯的法拉第效率的影响。采用SnOx(100-8)/GDL电极（即T和δ T分别为100℃和8 h）作为阴极，在-1.6 V的控制电位下获得了87.1%的最高法拉第效率，优于文献报道的所有SnOx和Sn/SnOx催化剂。通过x射线光电子能谱和x射线衍射分析发现，珊瑚状结构的SnOx由snono和SnO2组成，其中snono被1 ~ 2 nm厚的SnO2膜覆盖，这为CO2电还原的催化活性位点做出了贡献。这种珊瑚结构的SnOx具有很高的耐用性，在连续工作20小时内，催化电流密度稳定在10 mAcm（-2）左右。本研究强调了氧化锡的正确形态和价态对水溶液中CO2还原过程中甲酸形成的控制作用。
Several catalyst materials composed of tin oxide composites (SnOx) with a novel coralline structure are synthesized by using a facile hydrothermal self-assembly process. The catalysts are then used to prepare a SnOx/GDL (gas diffusion layer) electrode for CO2 electroreduction to formate in 0.5m KHCO3 aqueous solution. Influential factors, such as hydrothermal synthesis temperature (T)/time (Delta t) and the valence state of Sn in the SnOx nanocatalysts, on both catalysts' morphologies, and Faradaic efficiency for formate production are investigated systematically. By using a SnOx(100-8)/GDL electrode (i.e. T and Delta t are 100 degrees C and 8 h, respectively) as the cathode, the high maximum faradaic efficiency of 87.1% is achieved at a controlled potential of -1.6 V, which is superior to all the reported SnOx and Sn/SnOx catalysts in the literature. By combining X-ray photoelectron spectroscopy and X-ray diffraction analysis, the coralline-structured SnOx is observed to be composed of SnO and SnO2, where the SnO is covered by a SnO2 film about 1-2 nm thick, which makes a contribution to the catalytically active sites for CO2 electroreduction. This coralline-structured SnOx exhibits high durability, as evaluated by a stable catalytic current density of approximately 10 mAcm(-2) over 20 h of continuous operation. This work highlights the controlling role of the correct morphology and the valence state of tin oxide on formate formation during CO2 reduction in aqueous solution.