The rational design and synthesis of hierarchically hollow nanostructures with controlled spatial architecture and composition are significant in electrocatalysis owing to their abundant active sites and the expedited electron/mass transfer. Electrocatalytic nitrate reduction to ammonia is of great interest from the points of environmental protection and energy saving. However, the development of this technology is hindered by the lack of efficient nitrate-to-ammonia electrocatalysts and the kinetically sluggish oxygen evolution reaction at the anode. Herein, a novel self-template conversion method was developed for the synthesis of Co₃ O₄@NiO hierarchical nanotubes (Co₃O₄@NiO HNTs) with NiO porous nanosheets assembled on Co₃O₄ nanotubes. The as-obtained Co₃O₄@NiO HNTs exhibited an outstanding performance for both the cathodic nitrate electroreduction to ammonia reaction and the anodic tetrahydroisoquinolines (THIQs) semi-dehydrogenation to dihydroisoquinolines (DHIQs). Importantly, a two-electrode system of Co₃O₄@NiO HNTs ∥ Co₃O₄@NiO HNTs was constructed for the simultaneous synthesis of ammonia and DHIQs with high selectivity and robust stability.

由于其丰富的活性位点和加速的电子/质量转移，具有可控空间结构和组成的分级空心纳米结构的合理设计和合成在电催化中具有重要意义。从环境保护和节能的角度出发，将电催化硝酸盐还原为氨非常重要。但是，由于缺乏有效的硝酸盐转化为氨的电催化剂以及阳极上动力学缓慢的氧释放反应，阻碍了该技术的发展。在这里，开发了一种新颖的自模板转换方法，用于合成Co ₃ O ₄ @NiO分层纳米管（Co ₃ O ₄ @NiO HNTs），并在Co上组装了NiO多孔纳米片。₃ O ₄纳米管。如此获得的Co ₃ O ₄ @NiO HNTs在硝酸盐阴极电还原成氨反应和阳极四氢异喹啉（THIQs）半脱氢成二氢异喹啉（DHIQs）方面均表现出优异的性能。重要的是，钴的双电极系统₃ ö ₄ @NiO HNTS∥钴₃ ö _4个@NiO HNTS构建了用于氨和DHIQs的以高选择性和鲁棒稳定性的同时合成。