Electrochemical nitrate reduction(eNO_(3)RR)and nitric oxide reduction(eNORR)to ammonia have emerged as promising and sustainable alternatives to the traditional Haber-Bosch method for ammonia production,particularly ...Electrochemical nitrate reduction(eNO_(3)RR)and nitric oxide reduction(eNORR)to ammonia have emerged as promising and sustainable alternatives to the traditional Haber-Bosch method for ammonia production,particularly within the recently proposed reverse artificial nitrogen cycle route:N_(2)→NO_(x)→NH_(3).Notably,experimental studies have demonstrated that eNORR exhibits superior performance over eNO_(3)RR on Cu6Sn5 catalysts.However,the fundamental mechanisms underlying this difference remain poorly understood.Herein,we performed systematic theoretical calculations to explore the reaction pathways,electronic structure effects,and potential-dependent Faradic efficiency associated with ammonia production via these two distinct electrochemical pathways(eNORR and eNO_(3)RR)on Cu6Sn5.By implementing an advanced‘adaptive electric field controlled constant potential(EFC-CP)’methodology combined with microkinetic modeling,we successfully reproduced the experimental observations and identified the key factors affecting ammonia production in both reaction pathways.It was found that eNORR outperforms eNO_(3)RR because it circumvents the ^(*)NO_(2) dissociation and ^(*)NO_(2) desorption steps,leading to distinct surface coverage of key intermediates between the two pathways.Furthermore,the reaction rates were found to exhibit a pronounced dependence on the surface coverage of ^(*)NO in eNORR and ^(*)NO_(2) in eNO_(3)RR.Specifically,the facile desorption of ^(*)NO_(2) on the Cu6Sn5 surface in eNO_(3)RR limits the attainable surface coverage of ^(*)NO,thereby impeding its performance.In contrast,the eNORR can maintain a high surface coverage of adsorbed ^(*)NO species,contributing to its enhanced ammonia production performance.These fundamental insights provide valuable guidance for the rational design of catalysts and the optimization of reaction routes,facilitating the development of more efficient,sustainable,and scalable techniques for ammonia production.展开更多
文摘Electrochemical nitrate reduction(eNO_(3)RR)and nitric oxide reduction(eNORR)to ammonia have emerged as promising and sustainable alternatives to the traditional Haber-Bosch method for ammonia production,particularly within the recently proposed reverse artificial nitrogen cycle route:N_(2)→NO_(x)→NH_(3).Notably,experimental studies have demonstrated that eNORR exhibits superior performance over eNO_(3)RR on Cu6Sn5 catalysts.However,the fundamental mechanisms underlying this difference remain poorly understood.Herein,we performed systematic theoretical calculations to explore the reaction pathways,electronic structure effects,and potential-dependent Faradic efficiency associated with ammonia production via these two distinct electrochemical pathways(eNORR and eNO_(3)RR)on Cu6Sn5.By implementing an advanced‘adaptive electric field controlled constant potential(EFC-CP)’methodology combined with microkinetic modeling,we successfully reproduced the experimental observations and identified the key factors affecting ammonia production in both reaction pathways.It was found that eNORR outperforms eNO_(3)RR because it circumvents the ^(*)NO_(2) dissociation and ^(*)NO_(2) desorption steps,leading to distinct surface coverage of key intermediates between the two pathways.Furthermore,the reaction rates were found to exhibit a pronounced dependence on the surface coverage of ^(*)NO in eNORR and ^(*)NO_(2) in eNO_(3)RR.Specifically,the facile desorption of ^(*)NO_(2) on the Cu6Sn5 surface in eNO_(3)RR limits the attainable surface coverage of ^(*)NO,thereby impeding its performance.In contrast,the eNORR can maintain a high surface coverage of adsorbed ^(*)NO species,contributing to its enhanced ammonia production performance.These fundamental insights provide valuable guidance for the rational design of catalysts and the optimization of reaction routes,facilitating the development of more efficient,sustainable,and scalable techniques for ammonia production.
