Bhunia Subhajit, Lu Linguo, Chatterjee Suzatra, Garaga Mounesha, Mayoral Alvaro, Head Ashley R, Greenbaum Steven G, Chen Zhongfang, Wu Xiaowei, Cabrera Carlos R
Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 West University Avenue, El Paso, Texas 79968, United States.
Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, United States.
ACS Omega. 2025 Apr 28;10(18):18829-18839. doi: 10.1021/acsomega.5c00568. eCollection 2025 May 13.
Covalent organic frameworks (COFs) with a two-dimensional (2D) topology have recently emerged as promising catalyst systems for the electrosynthesis of hydrogen peroxide (HO) from oxygen (O). However, designing 2D catalysts to achieve higher HO selectivity presents a significant challenge because of the extensive layer stacking and the aggregated active sites located in the basal planes. It results in lower atom utilization, which requires attention. In this study, we present two functionally similar COFs: one with a 2D rhombus topology (2D@BT_TPA-COF) and another with a three-dimensional (3D) noninterpenetrated topology (3D@BT_TPA-COF). Both COFs were utilized for the 2e oxygen reduction reaction (2e ORR). Tunning the dimensionality from 2D to 3D resulted in an increase in HO selectivity from approximately ∼56% to approximately ∼96% (at 0.4 V) and a rise in the turnover frequency (TOF) from 0.05 to 0.08 s at 0.3 V. Nonaggregated active site distribution over 3D topology, featuring higher active site exposure, provides better access to the O/electrolyte and facilitates electron transfer leading to higher 2e ORR activity and selectivity compared to the 2D counterpart.
具有二维（2D）拓扑结构的共价有机框架（COF）最近已成为从氧气（O）电合成过氧化氢（HO）的有前景的催化剂体系。然而，由于广泛的层堆叠和位于基面的聚集活性位点，设计二维催化剂以实现更高的HO选择性面临重大挑战。这导致较低的原子利用率，这一点需要关注。在本研究中，我们展示了两种功能相似的COF：一种具有二维菱形拓扑结构（2D@BT_TPA-COF），另一种具有三维（3D）非互穿拓扑结构（3D@BT_TPA-COF）。两种COF都用于2e氧还原反应（2e ORR）。将维度从二维调整为三维导致HO选择性从约56%增加到约96%（在0.4 V时），并且在0.3 V时周转频率（TOF）从0.05增加到0.08 s⁻¹。与二维对应物相比，三维拓扑结构上非聚集的活性位点分布具有更高的活性位点暴露，提供了更好的O₂/电解质接触，并促进电子转移，从而导致更高的2e ORR活性和选择性。
