Loading of redox-active metal Fe largely enhances the capacity of biochar to mitigate soil N2O emissions by promoting complete denitrification

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