Raciti David, Mao Mark, Wang Chao
Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, United States of America.
Nanotechnology. 2018 Jan 26;29(4):044001. doi: 10.1088/1361-6528/aa9bd7.
Mass transport plays an important role in CO reduction electrocatalysis. Albeit being more pronounced on nanostructured electrodes, the studies of mass transport for CO reduction have yet been limited to planar electrodes. We report here the development of a mass transport model for the electroreduction of CO on Cu nanowire electrodes. Fed with the experimental data from electrocatalytic studies, the local concentrations of CO, [Formula: see text] and OH on the nanostructured electrodes are calculated by solving the diffusion equations with spatially distributed electrochemical reaction terms incorporated. The mass transport effects on the catalytic activity and selectivity of the Cu nanowire electrocatalysts are thus discussed by using the local pH as the descriptor. The established correlations between the electrocatalytic performance and the local pH shows that, the latter does not only determine the acid-base reaction equilibrium, but also regulates the mass transport and reaction kinetics. Based on these findings, the optimal range of local pH for CO reduction is discussed in terms of a fine balance among the suppression of hydrogen evolution, improvement of C product selectivity and limitation of CO supply. Our work highlights the importance of understanding the mass transport effects in interpretation of CO reduction electrocatalysis on high-surface-area catalysts.
传质在CO还原电催化中起着重要作用。尽管在纳米结构电极上更为显著，但CO还原的传质研究仍局限于平面电极。我们在此报告了一种用于在铜纳米线电极上电还原CO的传质模型的开发。根据电催化研究的实验数据，通过求解包含空间分布电化学反应项的扩散方程，计算了纳米结构电极上CO、[公式：见原文]和OH的局部浓度。通过使用局部pH作为描述符，讨论了传质对铜纳米线电催化剂催化活性和选择性的影响。电催化性能与局部pH之间建立的相关性表明，后者不仅决定酸碱反应平衡，还调节传质和反应动力学。基于这些发现，从抑制析氢、提高C产物选择性和限制CO供应之间的精细平衡角度讨论了CO还原的局部pH最佳范围。我们的工作突出了理解传质效应在解释高表面积催化剂上CO还原电催化中的重要性。
