Xu Xuefei, Deng Qingming, Chen Hsiao-Chien, Humayun Muhammad, Duan Delong, Zhang Xia, Sun Huachuan, Ao Xiang, Xue Xinying, Nikiforov Anton, Huo Kaifu, Wang Chundong, Xiong Yujie
School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics, Optics Valley Laboratory, Huazhong University of Science and Technology, Wuhan 430074, China.
Physics Department and Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, Huaiyin Normal University, Huaian 223300, China.
Research (Wash D C). 2022 Jun 27;2022:9837109. doi: 10.34133/2022/9837109. eCollection 2022.
Electrocatalytic urea oxidation reaction (UOR) is regarded as an effective yet challenging approach for the degradation of urea in wastewater into harmless N and CO. To overcome the sluggish kinetics, catalytically active sites should be rationally designed to maneuver the multiple key steps of intermediate adsorption and desorption. Herein, we demonstrate that metal-organic frameworks (MOFs) can provide an ideal platform for tailoring binary active sites to facilitate the rate-determining steps, achieving remarkable electrocatalytic activity toward UOR. Specifically, the MOF (namely, NiMn-BDC) based on Ni/Mn sites and terephthalic acid (BDC) ligands exhibits a low voltage of 1.317 V to deliver a current density of 10 mA cm. As a result, a high turnover frequency (TOF) of 0.15 s is achieved at a voltage of 1.4 V, which enables a urea degradation rate of 81.87% in 0.33 M urea solution. The combination of experimental characterization with theoretical calculation reveals that the Ni and Mn sites play synergistic roles in maneuvering the evolution of urea molecules and key reaction intermediates during the UOR, while the binary Ni/Mn sites in MOF offer the tunability for electronic structure and -band center impacting on the intermediate evolution. This work provides important insights into active site design by leveraging MOF platform and represents a solid step toward highly efficient UOR with MOF-based electrocatalysts.
电催化尿素氧化反应（UOR）被认为是一种将废水中的尿素降解为无害的氮和一氧化碳的有效但具有挑战性的方法。为了克服缓慢的动力学，应合理设计催化活性位点以操控中间吸附和解吸的多个关键步骤。在此，我们证明金属有机框架（MOF）可以提供一个理想的平台来定制二元活性位点，以促进速率决定步骤，实现对UOR的显著电催化活性。具体而言，基于镍/锰位点和对苯二甲酸（BDC）配体的MOF（即NiMn-BDC）在1.317 V的低电压下可提供10 mA cm的电流密度。结果，在1.4 V的电压下实现了0.15 s的高周转频率（TOF），这使得在0.33 M尿素溶液中的尿素降解率达到81.87%。实验表征与理论计算相结合表明，镍和锰位点在UOR过程中操控尿素分子和关键反应中间体的演化中发挥协同作用，而MOF中的二元镍/锰位点为电子结构和能带中心提供了可调性，影响中间产物的演化。这项工作通过利用MOF平台为活性位点设计提供了重要见解，并代表了迈向基于MOF的电催化剂实现高效UOR的坚实一步。
