苏州大学吴张雄团队报道了有序介孔碳上空间分离Cu/Ru在大电位窗下用于硝酸盐的高级氨电合成。相关研究成果于2024年8月28日发表于国际一流学术期刊《美国化学会杂志》。

废水中的硝酸盐（NO₃^-）对人类健康和生态环境构成严重威胁。电催化NO₃^-还原为氨（NH₃）反应（NO₃-RR）是一种有前景的无碳能源途径，可实现NO₃^-的去除和可持续的NH₃合成。然而，由于复杂的多电子还原过程，在宽电势窗口下实现高法拉第效率仍然是一个挑战。

该文中，研究人员设计了一种由氮掺杂的有序介孔碳载体制成的空间分离的双金属串联电催化剂，其内部包封有超小和高含量的Cu纳米颗粒，外表面分散有大和低含量的Ru纳米颗粒（表示为Ru/Cu@NOMC)。在电催化NO₃^-RR中，Cu位点可以快速将NO₃^-转化为吸附的NO₂^-（*NO₂^-），而Ru位点可以有效地产生活性氢（*H），以增强Cu位点上将*NO₂^-转化为NH₃的动力学。

由于Cu和Ru位点之间的协同效应，Ru/Cu@NOMC与可逆氢电极（RHE）相比，在0.1 V下显示出约100%的最大NH₃法拉第效率（FENH₃），在0.5 V下显示了1267 mmol gcat-1 h-1的高NH3收率。有限元法（FEM）模拟和电化学原位拉曼光谱表明，由于原位限制效应，介孔骨架可以提高中间浓度。由于铜-钌协同效应和中孔限制效应，FENH₃在Ru/Cu@NOMC催化剂上再90%以上的范围内具有约500 mV的宽电位窗口，在156小时内具有优异的NH₃生产稳定性。

附：英文原文

Title: Spatially Separated Cu/Ru on Ordered Mesoporous Carbon for Superior Ammonia Electrosynthesis from Nitrate over a Wide Potential Window

Author: Jia-Jia Zhang, Yao-Yin Lou, Zhangxiong Wu, Xiaoyang Jerry Huang, Shi-Gang Sun

Issue&Volume: August 28, 2024

Abstract: Nitrate (NO3–) in wastewater poses a serious threat to human health and the ecological environment. The electrocatalytic NO3– reduction to ammonia (NH3) reaction (NO3–RR) emerges as a promising carbon-free energy route for enabling NO3– removal and sustainable NH3 synthesis. However, it remains a challenge to achieve high Faraday efficiencies at a wide potential window due to the complex multiple-electron reduction process. Herein, spatially separated dual-metal tandem electrocatalysts made of a nitrogen-doped ordered mesoporous carbon support with ultrasmall and high-content Cu nanoparticles encapsulated inside and large and low-content Ru nanoparticles dispersed on the external surface (denoted as Ru/Cu@NOMC) are designed. In electrocatalytic NO3–RR, the Cu sites can quickly convert NO3– to adsorbed NO2– (*NO2–), while the Ru sites can efficiently produce active hydrogen (*H) to enhance the kinetics of converting *NO2– to NH3 on the Cu sites. Due to the synergistic effect between the Cu and Ru sites, Ru/Cu@NOMC exhibits a maximum NH3 Faradaic efficiency (FENH3) of approximately 100% at 0.1 V vs reversible hydrogen electrode (RHE) and a high NH3 yield rate of 1267 mmol gcat–1 h–1 at 0.5 V vs RHE. Finite element method (FEM) simulation and electrochemical in situ Raman spectroscopy revealed that the mesoporous framework can enhance the intermediate concentration due to the in situ confinement effect. Thanks to the Cu–Ru synergistic effect and the mesopore confinement effect, a wide potential window of approximately 500 mV for FENH3 over 90% and a superior stability for NH3 production over 156 h can be achieved on the Ru/Cu@NOMC catalyst.

DOI: 10.1021/jacs.4c06657

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c06657