Designing Efficient Nitrate Reduction Electrocatalysts by Identifying and Optimizing Active Sites of Co-Based Spinels

Cobalt-based spinel oxides (i.e., Co3O4) are emerging as low-cost and selective electrocatalysts for the electrochemical nitrate reduction reaction (NO3–RR) to ammonia (NH3), although their activity is still unsatisfactory and the genuine active site is unclear. Here, we discover that the NO3–RR activity of Co3O4 is highly dependent on the geometric location of the Co site, and the NO3–RR prefers to occur at octahedral Co (CoOh) rather than tetrahedral Co (CoTd) sites. Moreover, CoOhO6 is electrochemically transformed to CoOhO5 along with the formation of O vacancies (Ov) during the process of NO3–RR. Both experimental and theoretic results reveal that in situ generated CoOhO5–Ov configuration is the genuine…

• NN
  National Natural Science Foundation of China

  Awards: 22379100, U21A20312
• SS
  Shenzhen Science and Technology Innovation Program

  Award: RCYX20200714114535052
• BA
  Basic and Applied Basic Research Foundation of Guangdong Province

  Award: 2022B1515120084