Developing cost-efficient electrocatalysts for ambient N₂-to-NH₃ conversion and revealing the reaction mechanism are appealing yet challenging tasks. Some transition metal oxides have been recently used to catalyze the nitrogen reduction reaction (NRR), but their further applications are greatly impeded because of their questionable conductivity, poor dispersion, limited active sites, and so forth. Herein, three-dimensional Ni foam-supported urchin-like Al-doped Co₃O₄ nanospheres rich in surface oxygen vacancies (Al-Co₃O₄/NF) were prepared via a hydrothermal process and subsequent annealing treatment. It is shown that introducing Al atoms into Co₃O₄ effectively tunes the electronic properties of the catalyst, and the increased surface oxygen vacancies induced by Al doping facilitate the activation of nitrogen. What is more, this urchin-like nanostructure, demonstrating an ability to limit the coalescence of gas bubbles, enables the rapid removal of small gas bubbles and better exposure of active sites to N₂, thus yielding an impressive ammonia electrosynthesis activity (NH₃ yield rate: 6.48 × 10^–11 mol s^–1 cm^–2; Faradaic efficiency: 6.25%) in 0.1 M KOH. Electrochemical-based in situ Fourier transform infrared spectroscopy was employed to study the mechanism of NRR, indicating an associative alternating pathway.

中文翻译：

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富含表面氧空位的Urchin状Al掺杂的Co ₃ O ₄纳米球可实现高效的氨电合成

开发用于环境N _2-转化为NH _3的具有成本效益的电催化剂并揭示反应机理是吸引人的但具有挑战性的任务。最近已经将一些过渡金属氧化物用于催化氮还原反应（NRR），但由于其导电性不佳，分散性差，活性位点有限等原因，极大地阻碍了它们的进一步应用。在此，通过水热处理和随后的退火处理制备了富含表面氧空位（Al-Co ₃ O ₄ / NF）的三维Ni泡沫负载的海胆状掺Al的Co ₃ O ₄纳米球。结果表明，将Al原子引入Co ₃ O中_图4有效地调节了催化剂的电子性能，并且由Al掺杂引起的增加的表面氧空位促进了氮的活化。而且，这种具有类似海胆形状的纳米结构具有限制气泡聚结的能力，能够迅速去除小气泡，并使活性位点更好地暴露于N ₂，从而产生令人印象深刻的氨电合成活性（NH ₃收率）。速率：在0.1 M KOH中的6.48×10 ^–11 mol s ^–1 cm ^–2；法拉第效率：6.25％。基于电化学的原位傅里叶变换红外光谱用于研究NRR的机制，表明了缔合的交替途径。