The publication discusses the electrochemical reduction of nitrate (NO3−) to ammonia (NH3) using copper-based catalysts, focusing on the benefits of oxide-derived copper (OD-Cu) over standard copper (Cu). High nitrate concentrations, often from agricultural runoff and industrial waste, lead to environmental issues like eutrophication and pose health risks due to nitrite (NO2−) formation.
Key points include:
1.Catalyst Performance: OD-Cu demonstrates significantly better Faradaic efficiency (FE) for converting NO3− to NH3 compared to Cu, particularly in mixed feeds of NO3− and NO2−. The efficiency of OD-Cu, which can convert nitrite to ammonia without needing a co-catalyst, supports the hypothesis of distinct active sites for the two-step reduction process.
2.Mechanism and Active Sites: The publication proposes that OD-Cu has two types of active sites: one for converting NO3− to NO2− (Site A) and another for converting NO3− to NH3 (Site B). This dual-site mechanism allows for more efficient utilization of both nitrate and nitrite, leading to higher ammonia production rates when both substrates are present.
3.Experimental Results: The study involved systematically varying the composition of nitrate and nitrite in the electrolysis feed. Results indicated a "volcanic" relationship between the proportion of nitrate and ammonia production rates with OD-Cu, unlike the linear trend observed with Cu, confirming the distinct site hypothesis.
4.Spectroscopic Analysis: In-situ spectroscopy showed that OD-Cu effectively facilitates the conversion of NO2− to NH3, as indicated by stronger NH3 signals compared to NO2− signals at negative potentials, further validating the proposed mechanism.
5.Comparative Studies: The findings suggest that standard Cu catalysts predominantly generate nitrite and struggle to convert it to ammonia, potentially due to weak binding or high activation energy barriers for further reduction.
Overall, the research highlights the potential of OD-Cu catalysts for efficient nitrate reduction, offering insights into optimizing catalytic processes for environmental remediation and ammonia production.
文献链接：
https://pubs.acs.org/doi/full/10.1021/jacs.4c13219
