Tuning the Catalytic Preference of Ruthenium Catalysts for Nitrogen Reduction by Atomic Dispersion

• Published in: Advanced functional materials Vol. 30; no. 6
• Main Authors: Yu, Bing, Li, Hao, White, Jai, Donne, Scott, Yi, Jiabao, Xi, Shibo, Fu, Yang, Henkelman, Graeme, Yu, Hai, Chen, Zuliang, Ma, Tianyi
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01-02-2020
• Subjects: Ammonia; ammonia synthesis; Bulk density; Carbon nitride; Catalytic activity; Chemical reduction; Density functional theory; Electrocatalysts; g‐C3N4; hydrogen evolution; Materials science; Noble metals; Organic chemistry; Ruthenium; Selectivity; single atoms; Tuning
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201905665

Developing cost‐effective, high‐performance nitrogen reduction reaction (NRR) electrocatalysts is required for the production of green and low‐cost ammonia under ambient conditions. Here, a strategy is proposed to adjust the reaction preference of noble metals by tuning the size and local chemical environment of the active sites. This proof‐of‐concept model is realized by single ruthenium atoms distributed in a matrix of graphitic carbon nitride (Ru SAs/g‐C3N4). This model is compared, in terms of the NRR activity, to bulk Ru. The as‐synthesized Ru SAs/g‐C3N4 exhibits excellent catalytic activity and selectivity with an NH3 yield rate of 23.0 µg mgcat−1 h−1 and a Faradaic efficiency as high as 8.3% at a low overpotential (0.05 V vs the reversible hydrogen electrode), which is far better than that of the bulk Ru counterpart. Moreover, the Ru SAs/g‐C3N4 displays a high stability during five recycling tests and a 12 h potentiostatic test. Density functional theory calculations reveal that compared to bulk Ru surfaces, Ru SAs/g‐C3N4 has more facile reaction thermodynamics, and the enhanced NRR performance of Ru SAs/g‐C3N4 originates from a tuning of the d‐electron energies from that of the bulk to a single‐atom, causing an up‐shift of the d‐band center toward the Fermi level.
Ru SAs/g‐C3N4 exhibits excellent catalytic activity and selectivity, with an NH3 yield rate of 23.0 µg mgcat−1 h−1 and a Faradaic efficiency as high as 8.3% at 0.05 V versus reversible hydrogen electrode, which is far better than that of the bulk Ru counterpart. This is because Ru SAs/g‐C3N4 has stronger N2 adsorption and less H poisoning at the reactive sites.