Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry
Nanomorphology-Enhanced Gas-Evolution Intensifies CO2 Reduction Electrochemistry
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DOI：
10.1021/acssuschemeng.7b00023
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发表时间：
2017-05-01
影响因子：
8.4
通讯作者：
Sinton, David
中科院分区：
文献类型：
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作者：
Burdyny, Thomas;Graham, Percival J.;Sinton, David
纳米结构的CO2还原催化剂现在以日益提高的塔菲尔斜率和低过电位实现了接近统一的反应选择性。由于具有优异的表面反应动力学，这些催化剂在电流密度约为1000 V时遇到CO2传质限制。20 mA cm（-2）。我们在这里表明，-除了影响反应速率和局部反应物浓度-纳米结构电极的形态增强远程CO2传输通过其对气体演化的影响。更尖锐的针状形态可以成核和释放小至20 μ m的气泡，导致与单独的基于纳米颗粒的催化剂相比，极限电流密度增加4倍。通过将这一观察结果扩展到解释电极表面附近气泡诱导的质量传输的扩散模型中，扩散传输可以直接与电流密度和操作条件相关联，从而确定>100 mA cm（-2）生产的有效途径。我们进一步扩展这个模型来研究质量传输的影响，同时实现高选择性和电流密度的C2还原产物，确定精确控制的本地流体环境作为一个关键步骤，生产C2的C1产品。
Nanostructured CO2 reduction catalysts now achieve near-unity reaction selectivity at increasingly improved Tafel slopes and low overpotentials. With excellent surface reaction kinetics, these catalysts encounter CO2 mass transport limitations at current densities ca. 20 mA cm(-2). We show here that- in addition to influencing reaction rates and local reactant concentration- the morphology of nanostructured electrodes enhances long-range CO2 transport via their influence on gas-evolution. Sharper needle morphologies can nucleate and release bubbles as small as 20 mu m, leading to a 4-fold increase in the limiting current density compared to a nanoparticle-based catalyst alone. By extending this observation into a diffusion model that accounts for bubble-induced mass transport near the electrode's surface, diffusive transport can be directly linked to current densities and operating conditions, identifying efficient routes to >100 mA cm(-2) production. We further extend this model to study the influence of mass transport on achieving simultaneously high selectivity and current density of C2 reduction products, identifying precise control of the local fluid environment as a crucial step necessary for producing C2 over C1 products.