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FeOx Overcoating on Pd/C Catalyst by Atomic Layer Deposition Enhances the Catalytic Activity in Dehydrogenation of Formic Acid
路军岭
Author NameAffiliationE-mail
路军岭 University of Science and Technology of China junling@ustc.edu.cn 
Abstract:
Hydrogen generation from formic acid (FA) has received significant attention. The challenge is to obtain a highly active catalyst under mild conditions for practical applications. Here atomic layer deposition (ALD) of FeOx was performed to deposit an ultrathin oxide overcoating layer to a Pd/C catalyst, therein the FeOx coverage was precisely controlled by ALD cycles. Transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) measurements suggest that the FeOx overcoating layer improved the thermal stability of Pd nanoparticles (NPs). X-ray photoelectron spectroscopy (XPS) measurement showed that deposition of FeOx on the Pd NPs caused a positive shift of Pd 3d binding energy. In the FA dehydrogenation reaction, the ultrathin FeOx layer on the Pd/C could considerably improve the catalytic activity, and Pd/C coated with 8 cycles of FeOx showed an optimized activity turnover frequency which was about 2 times higher than the uncoated one. The improved activities were in a volcano-shape as the number of FeOx ALD cycles, indicating the coverage of FeOx is critical for the optimized activity. In summary, simultaneous improvements of activity and thermal stability of Pd/C catalyst by ultrathin FeOx overlayer suggest to be an effective way to design active catalysts for the FA dehydrogenation reaction.
Key words:  formic acid, hydrogen generation, atomic layer deposition, FeOx overcoat, Pd catalyst
FundProject:
通过原子层沉积技术沉积的FeOx包裹层可显著提高Pd/C催化剂在甲酸分解反应中的催化活性
路军岭
摘要:
甲酸分解制氢气近几年引起了人们的极大关注。该反应面临的巨大挑战是设计出具有在室温条件下的高活性催化剂。该项工作用原子层沉积技术(ALD)对Pd/C催化剂进行FeOx包裹,并通过改变ALD周期数精细控制FeOx的覆盖度。根据透射电子显微镜和粉末X射线衍射结果,我们发现FeOx包裹层在一定程度上可以提高Pd纳米颗粒的热稳定性。X-射线光电子能谱实验发现FeOx沉积到Pd颗粒表面上后,可以导致Pd 3d 电子束缚能变大,说明其与Pd颗粒有很强的相互作用。在甲酸放氢反应中,FeOx包裹后的催化剂的活性随着FeOx ALD周期数先升高后降低,呈火山型曲线。其中,经过8个ALD周期包裹的样品相对于Pd/C催化剂表现出了最佳的活性,相比未包裹的Pd/C催化剂,催化活性提高了一倍。总之,该工作提供了一种提高Pd催化剂在甲酸分解反应中活性的有效方法,为今后改性催化剂并应用于其他反应奠定了基础
关键词:  甲酸,氢气释放,原子层沉积,铁氧化物包裹,Pd催化剂
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