Unraveling the Activity Trends and Design Principles of Single-Atom Catalysts for Nitrate Electrocatalytic Reduction
Haibo Yin, Dong Feng, Haiwei Su, Zechao Zhuang, Yunlong Wang, Dingsheng Wang, Yue Peng, Junhua Li
Abstract
Electrocatalytic nitrate (NO 3 – ) reduction represents one of the most promising approaches to mitigate NO 3 – pollution and yield NH 3, but it is still challenged by the atomic economy and selectivity issues of substantial active sites. Here, we describe a comprehensive investigation on a series of single-atom catalysts (SACs) using nitrogen-doped carbon as substrate (metal/NC). The essence of activity is related to the extent of the electron transfer capacity (SAs → NO 3 – ). Among these examined SACs, the Cu/NC presents good performance toward NH 3 synthesis, i.e., a maximum NH 3 Faradaic efficiency of 100% with a high NH 3 yield rate of up to 32,300 μg h –1 mg cat. –1 . X-ray absorption fine structure spectra and density functional theory calculations provide evidence that the electronic structure of Cu–N 4 coordination prohibits the formation of N 2, N 2 O, and H 2 and facilitates the orbital hybridization between the 2p orbitals of NO 3 – and 3d orbitals of Cu single-atom sites. Our study is believed to provide fundamental guidance for the future design of highly efficient electrocatalysts in NO 3 – reduction to NH 3 .