"Revealing Molecular Mechanisms in Hierarchical Nanoporous Carbon via Nuclear Magnetic Resonance"

Haiyan Mao: Jing Tang, Jun Xu,Yucan Peng, Jun Chen, Bing Wu, Yuanwen Jiang, Kaipeng Hou, Shuo Chen, Jiangyan Wang, Hye Ryoung Lee, David M. Halat, Bing Zhang, Wei Chen, Ariel Z. Plantz, Zhiyi Lu, Yi Cui, Jeffrey A. Reimer; Matter, 10/22/20.

Additional Authors: Jing Tang, Jun Xu,Yucan Peng, Jun Chen, Bing Wu, Yuanwen Jiang, Kaipeng Hou, Shuo Chen, Jiangyan Wang, Hye Ryoung Lee, David M. Halat, Bing Zhang, Wei Chen, Ariel Z. Plantz, Zhiyi Lu, Yi Cui, Jeffrey A. Reimer

Abstract:

Hierarchical nanoporous carbons (HNC) have been proven to be an effective adsorbent for the adsorption of volatile organic compounds (VOCs) and CO2. However, questions remain regarding the hierarchical structure regulation, the adsorption mechanisms of adsorbate uptake, and interactions within the HNC. We synthesize HNC from wood, using a microwave-induced heating method incorporating K2CO3 activation. Our HNC exhibit Murray’s law multiscale structures, prompting a molecular-scale study of adsorbate adsorption via nuclear magnetic resonance (NMR). NMR chemical shifts are consistent with ring-current effects from the adsorbent. Our NMR technique provides a convenient way to quantitate adsorption of adsorbate in HNC. VOC vapor adsorption results show NMR chemical-shift changes with time, suggesting initial adsorption into mesopores, followed by diffusion into micropores. Schroeder’s paradox is demonstrated by differences in observed shifts for adsorbed liquid vis-à-vis vapor phase in these HNC. These HNC show high CO2 adsorption capacity, portending applications to carbon capture.