Zhong Xiu, Yuan Enxian, Yang Fu, Liu Yang, Lu Hao, Yang Jun, Gao Fei, Zhou Yu, Pan Jianming, Zhu Jiawei, Yu Chao, Zhu Chengzhang, Yuan Aihua, Ang Edison Huixiang
School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212100, China.
School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China.
Proc Natl Acad Sci U S A. 2023 Oct 3;120(40):e2306673120. doi: 10.1073/pnas.2306673120. Epub 2023 Sep 25.
Electrocatalytic nitrogen reduction is a challenging process that requires achieving high ammonia yield rate and reasonable faradaic efficiency. To address this issue, this study developed a catalyst by in situ anchoring interfacial intergrown ultrafine MoO nanograins on N-doped carbon fibers. By optimizing the thermal treatment conditions, an abundant number of grain boundaries were generated between MoO nanograins, which led to an increased fraction of oxygen vacancies. This, in turn, improved the transfer of electrons, resulting in the creation of highly active reactive sites and efficient nitrogen trapping. The resulting optimal catalyst, MoO/C, outperformed commercial MoO and state-of-the-art N reduction catalysts, with NH yield and Faradic efficiency of 173.7 μg h mg and 27.6%, respectively, under - 0.7 V vs. RHE in 1 M KOH electrolyte. In situ X-ray photoelectron spectroscopy characterization and density functional theory calculation validated the electronic structure effect and advantage of N adsorption over oxygen vacancy, revealing the dominant interplay of N and oxygen vacancy and generating electronic transfer between nitrogen and Mo(IV). The study also unveiled the origin of improved activity by correlating with the interfacial effect, demonstrating the big potential for practical N reduction applications as the obtained optimal catalyst exhibited appreciable catalytic stability during 60 h of continuous electrolysis. This work demonstrates the feasibility of enhancing electrocatalytic nitrogen reduction by engineering grain boundaries to promote oxygen vacancies, offering a promising avenue for efficient and sustainable ammonia production.
电催化氮还原是一个具有挑战性的过程，需要实现高氨产率和合理的法拉第效率。为了解决这个问题，本研究通过在氮掺杂碳纤维上原位锚定界面共生的超细MoO纳米颗粒来制备一种催化剂。通过优化热处理条件，在MoO纳米颗粒之间产生了大量的晶界，这导致氧空位分数增加。这反过来又改善了电子转移，从而产生了高活性的反应位点和高效的氮捕获。所得的最佳催化剂MoO/C在1 M KOH电解液中相对于可逆氢电极（RHE）为-0.7 V时，氨产率和法拉第效率分别为173.7 μg h mg和27.6%，优于商业MoO和最先进的氮还原催化剂。原位X射线光电子能谱表征和密度泛函理论计算验证了电子结构效应以及氮相对于氧空位吸附的优势，揭示了氮与氧空位之间的主要相互作用，并在氮和Mo(IV)之间产生了电子转移。该研究还通过与界面效应相关联揭示了活性提高的起源，表明了实际氮还原应用的巨大潜力，因为所获得的最佳催化剂在连续电解60小时期间表现出可观的催化稳定性。这项工作证明了通过设计晶界来促进氧空位从而增强电催化氮还原的可行性，为高效可持续的氨生产提供了一条有前景的途径。
