Direct ethanol fuel cells (DEFCs) are a promising technology for the generation of electricity via the direct conversion of ethanol into CO₂, showing higher thermodynamic efficiency and volumetric energy density than hydrogen fuel cells. However, implementation of DEFCs is hampered by the low CO₂ selectivity during the ethanol oxidation reaction (EOR). Comprehensive understanding of the electro-kinetics and reaction pathways of CO₂ generation via CC bond-breaking is not only a fundamental question for electro-catalysis, but also a key technological challenge since practical implementation of DEFC technology is contingent on its ability to selectively oxidize ethanol into CO₂ to achieve exceptional energy density through 12-electron transfer reaction. Here, we present comprehensive in situ potentiodynamics studies of CO₂ generation during the EOR on Pt, Pt/SnO₂ and Pt/Rh/SnO₂ catalysts using a house-made electrochemical cell equipped with a CO₂ microelectrode. Highly sensitive CO₂ measurements enable the real time detection of the partial pressure of CO₂ during linear sweep voltammetry measurements, through which electro-kinetics details of CO₂ generation can be obtained. In situ CO₂ measurements provide the mechanistic understanding of potentiodynamics of the EOR, particularly the influence of ^∗OH adsorbates on CO₂ generation rate and selectivity. Density functional theory (DFT) simulations of Pt, Pt/SnO₂, and Pt/Rh/SnO₂ surfaces clarify reaction details over these catalysts. Our results show that at low potentials, inadequate ^∗OH adsorbates impair the removal of reaction intermediates, and thus Pt/Rh/SnO₂ exhibited the best performance toward CO₂ generation, while at high potentials, Rh sites were overwhelmingly occupied (poisoned) by ^∗OH adsorbates, and thus Pt/SnO₂ exhibited the best performance toward CO₂ generation.

直接乙醇燃料电池（DEFC）是一种通过将乙醇直接转化为CO ₂来发电的有前途的技术，与氢燃料电池相比，其显示出更高的热力学效率和体积能密度。但是，在乙醇氧化反应（EOR）期间，由于CO ₂选择性低，阻碍了DEFC的实施。全面理解通过C C键断裂产生CO ₂的动力学和反应途径不仅是电催化的基本问题，而且是关键的技术挑战，因为DEFC技术的实际实施取决于其选择性地选择碳的能力。将乙醇氧化成CO ₂通过12电子转移反应实现出色的能量密度。在这里，我们介绍了使用配备有CO ₂微电极的自制电化学电池在Pt，Pt / SnO ₂和Pt / Rh / SnO ₂催化剂上进行EOR期间CO ₂生成的综合原位电动力学研究。高度敏感的CO ₂测量值可以在线性扫描伏安法测量过程中实时检测CO ₂的分压，从而可以获取产生CO _2的电动细节。原位CO ₂测量结果提供了对EOR电位动力学的机械理解，尤其是^＊ OH吸附物对CO ₂生成速率和选择性的影响。Pt，Pt / SnO ₂和Pt / Rh / SnO ₂表面的密度泛函理论（DFT）模拟阐明了这些催化剂的反应细节。我们的结果表明，在低电势下，不足的^＊ OH吸附物会阻碍反应中间体的去除，因此Pt / Rh / SnO ₂表现出最佳的CO ₂生成性能，而在高电势下，Rh位点被绝大多数占据（中毒）^* OH吸附，因此Pt / SnO ₂在产生CO _2方面表现出最好的性能。