Yan Jianyue, Liu Peng, Li Jiawen, Huang Hao, Song Wenbo
College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
Department of Microsystems, University of South-Eastern Norway, Borre, 3184, Norway.
Small. 2024 Apr;20(14):e2308617. doi: 10.1002/smll.202308617. Epub 2023 Nov 20.
Cobalt spinel oxides, which consist of tetrahedral site (AO) and octahedral site (BO), are a potential group of transition metal oxides (TMO) for electrocatalytic nitrate reduction reactions to ammonia (NRA). Identifying the true active site in spinel oxides is crucial to designing advanced catalysts. This work reveals that the CoO site is the dominant site for NRA through the site substitution strategy. The suitable electronic configuration of Co at the octahedral site leads to a stronger interaction between the Co d-orbital and the O p-orbital in O-containing intermediates, resulting in a high-efficiency nitrate-to-ammonia reduction. Furthermore, the substitution of metallic elements at the AO site can affect the charge density at the BO site via the structure of A-O-B. Thereafter, Ni and Cu are introduced to replace the tetrahedral site in spinel oxides and optimize the electronic structure of CoO. As a result, NiCoO exhibits the best activity for NRA with an outstanding yield of NH (15.49 mg cm h) and FE (99.89%). This study introduces a novel paradigm for identifying the active site and proposes an approach for constructing high-efficiency electrocatalysts for NRA.
由四面体位置（AO）和八面体位置（BO）组成的钴尖晶石氧化物是用于电催化硝酸盐还原制氨（NRA）的一类潜在的过渡金属氧化物（TMO）。确定尖晶石氧化物中的真正活性位点对于设计先进催化剂至关重要。这项工作通过位点取代策略揭示了CoO位点是NRA的主要位点。八面体位置的Co具有合适的电子构型，导致Co d轨道与含O中间体中的O p轨道之间的相互作用更强，从而实现了高效的硝酸盐到氨的还原。此外，AO位点的金属元素取代可以通过A - O - B结构影响BO位点的电荷密度。此后，引入Ni和Cu来取代尖晶石氧化物中的四面体位置并优化CoO的电子结构。结果，NiCoO对NRA表现出最佳活性，NH₃产率出色（15.49 mg cm⁻² h⁻¹），法拉第效率（FE）为99.89%。本研究引入了一种识别活性位点的新范式，并提出了一种构建用于NRA的高效电催化剂的方法。
