Zhang Sai, Yi Jianjian, Liu Mengdi, Shi Lan, Chen Min, Wu Limin
Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, China.
College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China.
ACS Nano. 2024 Oct 1;18(39):26722-26732. doi: 10.1021/acsnano.4c06754. Epub 2024 Sep 18.
While electrocatalytic reduction of nitrate to ammonia presents a sustainable solution for addressing both the environmental and energy issues within the nitrogen cycle, it remains a great challenge to achieve high selectivity and activity due to undesired side reactions and sluggish reaction kinetics. Here, we fabricate a series of metal-N-C catalysts that feature hierarchically ordered porous structure and high-density atomically dispersed metals (HD M/PNC). Specifically, the as-prepared HD Fe/PNC catalyst achieves an ammonia production rate of 21.55 mol g h that is at least 1 order of magnitude enhancement compared with that of the reported metal-N-C catalysts, while maintaining a 92.5% Faradaic efficiency when run at 500 mA cm for 300 h. In addition to abundant active sites, such high performance benefits from the fact that the high-density Fe can more significantly activate the adjacent N/C sites through charge redistribution for improved water adsorption/dissociation, providing sufficient active hydrogen to Fe sites for nitrate ammoniation, compared with the low-density counterpart. This finding deepens the understanding of high-density metal-N-C materials at the atomic scale and may further be used for designing other catalysts.
虽然将硝酸盐电催化还原为氨为解决氮循环中的环境和能源问题提供了一种可持续的解决方案，但由于存在不期望的副反应和缓慢的反应动力学，实现高选择性和活性仍然是一个巨大的挑战。在此，我们制备了一系列具有分级有序多孔结构和高密度原子分散金属（HD M/PNC）的金属-N-C催化剂。具体而言，所制备的HD Fe/PNC催化剂实现了21.55 μmol g-1 h-1的氨产率，与已报道的金属-N-C催化剂相比至少提高了1个数量级，同时在500 mA cm-2下运行300 h时保持92.5%的法拉第效率。除了丰富的活性位点外，如此高的性能得益于高密度的铁能够通过电荷重新分布更显著地激活相邻的N/C位点，从而改善水的吸附/解离，与低密度对应物相比，为铁位点提供足够的活性氢用于硝酸盐氨化。这一发现加深了对高密度金属-N-C材料在原子尺度上的理解，并可能进一步用于设计其他催化剂。
