浙江大学单冰团队报道了硝酸选择性电还原制氨的导电共价网络中的分子自组装。相关研究成果于2023年9月21日发表在《美国化学会杂志》。

水介质中的电化学硝酸盐（NO₃^–）还原为氨（NH₃）的合成提供了一种有用的方法。虽然研究集中在开发催化剂上，但催化剂中心周围的局部微环境对于控制电催化性能非常重要。

该文中，研究人员证明了集成在独立导电水凝胶中的自组装分子铁催化剂能够从NO₃选择性生产NH₃，其效率接近1。使用电催化水凝胶，在一系列负偏压下，NH₃选择性始终很高，这是由聚咔唑基电极基底的疏水性增加引起的。在弱酸性介质中，水凝胶电极的电润湿抑制了质子还原，提高了NO₃还原的选择性。该电催化水凝胶能够在高电流密度下连续生产NH₃至少100小时，NH₃选择性为～89%至98%。

该结果强调了为电催化剂构建内部疏水表面在控制水性介质中的选择性方面的作用。

附：英文原文

Title: Molecular Self-Assembly in Conductive Covalent Networks for Selective Nitrate Electroreduction to Ammonia

Author: Feiqing Sun, Yifan Gao, Mengjie Li, Yingke Wen, Yanjie Fang, Thomas J. Meyer, Bing Shan

Issue&Volume: September 21, 2023

Abstract: Electrochemical nitrate (NO3–) reduction in aqueous media provides a useful approach for ammonia (NH3) synthesis. While efforts are focused on developing catalysts, the local microenvironment surrounding the catalyst centers is of great importance for controlling electrocatalytic performance. Here, we demonstrate that a self-assembled molecular iron catalyst integrated in a free-standing conductive hydrogel is capable of selective production of NH3 from NO3– at efficiencies approaching unity. With the electrocatalytic hydrogel, the NH3 selectivity is consistently high under a range of negative biases, which results from the hydrophobicity increase of the polycarbazole-based electrode substrate. In mildly acidic media, proton reduction is suppressed by electro-dewetting of the hydrogel electrode, enhancing the selectivity of NO3– reduction. The electrocatalytic hydrogel is capable of continuous production of NH3 for at least 100 h with NH3 selectivity of ～89 to 98% at high current densities. Our results highlight the role of constructing an internal hydrophobic surface for electrocatalysts in controlling selectivity in aqueous media.

DOI: 10.1021/jacs.3c07320

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.3c07320