Synthesis and Characterization of Degradation‐Resistant Cu@CuPd Nanowire Catalysts for the Efficient Production of Formate and CO from CO 2
Synthesis and Characterization of Degradation‐Resistant Cu@CuPd Nanowire Catalysts for the Efficient Production of Formate and CO from CO 2
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DOI：
10.1002/celc.201900752
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发表时间：
2019-06
期刊：
影响因子：
4
通讯作者：
Yuhui Hou;R. Erni;R. Widmer;M. Rahaman;Huizhang Guo;R. Fasel;Pavel Moreno-García;Yucheng Zhang
中科院分区：
文献类型：
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作者：
Yuhui Hou;R. Erni;R. Widmer;M. Rahaman;Huizhang Guo;R. Fasel;Pavel Moreno-García;Yucheng Zhang
电催化剂的产品选择性和活性不仅是评价其整体性能的重要方面，而且在电催化反应过程中其稳定性和抗结构和成分降解的能力也是重要的。钯纳米颗粒(Pd-NPs)在极低过电位和中等过电位下可将二氧化碳转化为甲酸盐和一氧化碳(CO)，是一种优良的电催化剂。然而，由于Pd反应中心的不可逆CO中毒，这些催化剂存在快速降解的问题。在这里，我们报道了纳米双金属Pd45Cu55催化剂，表现出与纯Pd-NPs相似的选择性和活性，但表现出更好的降解稳定性和抗CO中毒能力。以铜纳米线(Cu-NWS)为起始原料(模板)，通过电偶置换反应合成了Pd45Cu55催化剂，在该模板上形成了表面受限的合金薄膜和相应的纳米粒子(记为Cu@CuPd-NWS)。FEForate≈80 %的法拉第效率(FE)在−为0.3 V时可达到RHE，从而清楚地证明了对于纯Pd-NPs来说，通过CO2氢化途径进行的反常CO2反应机理也可以转移到Pd基双金属体系中。在中等过电位下，产物选择性由选择性甲酸盐转变为主要的CO生成，最大法拉第效率为86 %。扩展的CO2电解液对甲酸盐和CO的生成都表现出了良好的降解稳定性，例如在20 h内，FeCO值保持在85 %±5 %。首次采用同位置高角环形暗场扫描电子显微镜结合能量色散X射线能谱和同位置扫描电子显微镜对双金属催化剂在CO2还原条件下的组成和结构稳定性进行了研究。
Not only are the product selectivity and the activity of electrocatalysts important aspects for the evaluation of their overall performance, but also their stability and resistance against structural and compositional degradation during the electrocatalytic reaction. Palladium nanoparticles (Pd‐NPs) have already been identified as superior electrocatalysts for the electrochemical conversion of CO2into formate at extremely low overpotentials and into carbon monoxide (CO) at medium overpotentials. However, these catalysts suffer from fast degradation, owing to irreversible CO poisoning of Pd reaction sites. Herein, we report on nanoparticulate bimetallic Pd45Cu55catalysts, demonstrating a similar selectivity and activity to the pure Pd‐NPs, but showing additional superior degradation stability and resistance against CO poisoning. Pd45Cu55catalysts were synthesized by means of a galvanic displacement reaction using copper nanowires (Cu‐NWs) as the starting material (template) for the galvanic displacement reaction, which leaves a surface‐confined alloy film and respective nanoparticles on the Cu‐NW template (denoted as Cu@CuPd‐NWs). A faradaic efficiency (FE) up to FEformate≈80 % can be achieved at −0.3 V vs. RHE, thus clearly proving that the ‘anomalous’ CO2reaction mechanism via the CO2hydrogenation pathway, discussed for pure Pd‐NPs, can also be transferred to Pd‐based bimetallic systems. At medium overpotentials, the product selectivity changes from selective formate to predominant CO formation with a maximum faradaic efficiency of FECO=86 %. Extended CO2electrolyses demonstrate, for both formate and CO production, superior degradation stability, for example, FECOremains at 85 %±5 % for the duration of 20 h. For the first time, identical location high‐angle annular dark‐field scanning transmission electron microscopy (IL‐HAADF‐STEM) in combination with energy‐dispersive X‐ray spectrometry and identical location scanning electron microscopy (IL‐SEM) were applied to demonstrate the compositional and structural stability of the bimetallic catalyst under CO2reduction conditions.