Nitrous oxide (N₂O) is a critical greenhouse gas and an ozone-depleting substance, with a global warming potential 298–310 times greater than that of CO₂. Mitigating N₂O emissions from soils has environmental benefits. Recent research indicates that biochar can serve as an “electron shuttle” to reduce N₂O emissions from soils. Electron shuttle is defined as organic molecules capable of reversibly receiving and donating electrons. Thus, biochar is expected to facilitate stepwise reduction of denitrification products, reducing N₂O to environmentally harmless N₂. However, it remains uncertain whether biochar’s capacity to mitigate N₂O can be enlarged by augmenting its function as an electron shuttle. Thus, this study prepared a biochar with enhanced electron shuttle potential by loading redox-active (Fe) onto biochar. The effectiveness of this biochar in mitigating soil N₂O emissions was investigated by incorporating it into the soil. The results showed that Fe-loaded biochar significantly augmented its function as an electron shuttle and dramatically reduced soil N₂O emissions by 92% compared to the original biochar. The degree of decrease in N₂O emissions was strongly associated with both the electron shuttle capacity and the concentration of redox-active Fe in the biochar. Additionally, Fe-loaded biochar significantly decreased the N₂O/(N₂O + N₂) emission ratio and increased the expression of the nosZ-II gene. Our findings suggest that redox-active Fe loading in biochar is an effective strategy to enhance its electron shuttle function. The augmented electron shuttle function of biochar can successfully facilitate N₂O mitigation emission by promoting complete denitrification.

一氧化二氮 (N ₂ O) 是一种重要的温室气体和臭氧消耗物质，其全球变暖潜力是 CO ₂的 298-310 倍。减少土壤中的 N ₂ O 排放具有环境效益。最近的研究表明，生物炭可以作为“电子穿梭机”来减少土壤中的N ₂ O 排放。电子穿梭被定义为能够可逆地接收和给予电子的有机分子。因此，生物炭有望促进反硝化产物的逐步还原，将N ₂ O还原为对环境无害的N ₂。然而，生物炭减轻N ₂ O的能力是否可以通过增强其作为电子穿梭机的功能来增强仍不确定。因此，本研究通过在生物炭上负载氧化还原活性（Fe）来制备具有增强电子穿梭电势的生物炭。通过将这种生物炭掺入土壤中，研究了其在减少土壤 N ₂ O 排放方面的有效性。结果表明，与原始生物炭相比，载铁生物炭显着增强了其作为电子穿梭的功能，并使土壤 N _{2 O 排放量显着减少了 92%。 N 2} O排放量的减少程度与生物炭中的电子穿梭能力和氧化还原活性Fe的浓度密切相关。此外，负载Fe的生物炭显着降低了N ₂ O/(N ₂ O + N _{2 )排放比并增加了}nosZ-II基因的表达。我们的研究结果表明，在生物炭中负载氧化还原活性铁是增强其电子穿梭功能的有效策略。生物炭增强的电子穿梭功能可以通过促进完全反硝化成功地促进N ₂ O减排。