Biochars containing abundant and diverse functional groups can influence soil nitrous oxide (N₂O) emissions. It remains unclear how these functional groups alter soil N₂O emissions and which specific functional groups are responsible. In this study, biochars containing differing functional group compositions were initially screened for their ability to mitigate N₂O emissions. Then, the mechanisms of the targeted functional group were assessed by loading the targeted functional group onto graphene, to exclude the potential effects of other functional groups, in order to test specific functional group effects on N₂O production and reduction in an agricultural soil and on a typical denitrifier strain (Thiobacillus denitrificans). The results showed that the abundance of the C=O (carboxyl and carbonyl functional groups) was significantly correlated (P < 0.01) with soil N₂O emissions and the N₂O/(N₂O+N₂) emission ratio, indicating that the carboxyl functional group plays a significant role in reducing the mitigation potential of biochar on soil N₂O emissions. Compared to the carboxyl-free graphene, the carboxyl-loaded graphene significantly decreased the genetic potential for N₂O reduction and increased the N₂O/(N₂O+N₂) emission ratio of the soil and the Thiobacillus denitrificans strain. The addition of an electron transfer inhibitor (N, N′-dicyclohexylcarbodiimide) eliminated the negative effect of the carboxyl functional group in terms of reducing N₂O emissions, suggesting that the inhibitory effect of the carboxyl functional group on N₂O reduction was likely caused by disruption of the electron transfer from biochar to N₂O-reducing microbes. Our results imply that the carboxyl functional group on biochar’s surface can negatively affect the potential of biochar to mitigate soil N₂O emissions.

含有丰富多样的官能团的生物炭会影响土壤一氧化二氮（N ₂ O）的排放。尚不清楚这些官能团如何改变土壤N ₂ O的排放以及哪些特定的官能团负责。在这项研究中，首先筛选了包含不同官能团组成的生物炭缓解N ₂ O排放的能力。然后，通过将目标官能团加载到石墨烯上来评估目标官能团的机制，以排除其他官能团的潜在影响，以测试特定官能团对农业土壤中N ₂ O产生和还原的影响。在典型的反硝化菌株上（反硝化硫杆菌（Thiobacillus denitrificans）。结果表明，C = O（羧基和羰基官能团）的丰度与土壤N ₂ O排放量和N ₂ O /（N ₂ O + N ₂）排放比显着相关（P <0.01），表明羧基官能团在减少生物炭对土壤N ₂ O排放的缓解潜力中起着重要作用。与不含羧基的石墨烯相比，含羧基的石墨烯显着降低了N ₂ O还原的遗传潜力，并增加了土壤和土壤中N ₂ O /（N ₂ O + N ₂）的排放比。反硝化硫杆菌。添加电子转移抑制剂（N，N'-二环己基碳二亚胺）消除了羧基官能团在减少N ₂ O排放方面的负面影响，表明羧基官能团对N ₂ O还原的抑制作用很可能这是由于电子从生物碳转移到还原N ₂ O的微生物的破坏所致。我们的结果表明，生物炭表面的羧基官能团可能会对生物炭减轻土壤N ₂ O排放的潜力产生负面影响。