Replacing Pt-based electrocatalysts for the oxygen reduction reaction (ORR) with high performance and low-cost non-precious metal catalysts is crucial for the commercialization of fuel cells.Herein,we present a highly...Replacing Pt-based electrocatalysts for the oxygen reduction reaction (ORR) with high performance and low-cost non-precious metal catalysts is crucial for the commercialization of fuel cells.Herein,we present a highly efficient Fe-N-C porous ORR electrocatalyst with FeNx moieties promoted by Fe2N nanoparticles derived from Fe-doped zeolitic imidazolate framework.The best-performing Fe-N-C/HPC-NH3 catalyst exhibits a superior ORR activity with an onset (E0) and half-wave (E1/2) potential of 0.945 and 0.803 V (RHE),respectively,which is comparable to those of the commercial Pt/C in acidic media.Probing and acid-leaching experiments prove that FeNx moieties play an important role in the ORR and the Fe2N can further improve the ORR activity.Density functional theory calculation reveals a synergistic effect that the existence of Fe2N weakens the adsorption of ORR intermediates on active sites and lowers the reaction free energy of the potential limiting step,thus facilitating the ORR.Both experimental evidence and theoretical analysis for the enhancement of ORR activity by Fe2N decoration in Fe-N-C catalyst might inspire a new strategy for rational design of high performance non-precious metal catalysts.展开更多
A novel strategy was developed to fabricate FeNx-doped carbon quantum dots(Fe-N-CQDs)to detect Cu^(2+) ions selectively as a fluorescence probe.The Fe-N-CQDs were synthesized by an efficient electrolysis of a carbon c...A novel strategy was developed to fabricate FeNx-doped carbon quantum dots(Fe-N-CQDs)to detect Cu^(2+) ions selectively as a fluorescence probe.The Fe-N-CQDs were synthesized by an efficient electrolysis of a carbon cloth electrode,which was coated with monoatomic ironanchored nitrogen-doped carbon(Fe-N-C).The obtained Fe-N-CQDs emitted blue fluorescence and possessed a quantum yield(QY)of 7.5%.An extremely wide linear relationship between the Cu^(2+) concentration and the fluorescence intensity was obtained in the range from 100 nmol L^(-1) to 1000 nmol L^(-1)(R^(2)=0.997),and the detection limit was calculated as 59 nmol L^(-1).Moreover,the Fe-N-CQDs demonstrated wide range pH compatibility between 2 and 13 due to the coordination between pyridine nitrogen and Fe^(3+),which dramatically reduced the affection of the protonation and deprotonation process between H^(+) and Fe-N-CQDs.It is notable that the Fe-N-CQDs exhibited a rapid response in Cu^(2+) detection,where stable quenching can be completed in 7 s.The mechanism of excellent selective detection of Cu^(2+) was revealed by energy level simulation that the LUMO level of Fe-N-CQDs(-4.37 eV)was close to the redox potential of Cu^(2+),thus facilitating the electron transport from Fe-N-CQDs to Cu^(2+).展开更多
基金the National Key Research and Development Program of China (No.2017YFA0206500)the National Natural Science Foundation of China (Nos.21802161,21673275,and 21533005).
文摘Replacing Pt-based electrocatalysts for the oxygen reduction reaction (ORR) with high performance and low-cost non-precious metal catalysts is crucial for the commercialization of fuel cells.Herein,we present a highly efficient Fe-N-C porous ORR electrocatalyst with FeNx moieties promoted by Fe2N nanoparticles derived from Fe-doped zeolitic imidazolate framework.The best-performing Fe-N-C/HPC-NH3 catalyst exhibits a superior ORR activity with an onset (E0) and half-wave (E1/2) potential of 0.945 and 0.803 V (RHE),respectively,which is comparable to those of the commercial Pt/C in acidic media.Probing and acid-leaching experiments prove that FeNx moieties play an important role in the ORR and the Fe2N can further improve the ORR activity.Density functional theory calculation reveals a synergistic effect that the existence of Fe2N weakens the adsorption of ORR intermediates on active sites and lowers the reaction free energy of the potential limiting step,thus facilitating the ORR.Both experimental evidence and theoretical analysis for the enhancement of ORR activity by Fe2N decoration in Fe-N-C catalyst might inspire a new strategy for rational design of high performance non-precious metal catalysts.
基金the National Natural Science Foundation of China(Nos.21776302 and 21776308)the Science Foundation of China University of Petroleum,Beijing(No.2462020YXZZ033).
文摘A novel strategy was developed to fabricate FeNx-doped carbon quantum dots(Fe-N-CQDs)to detect Cu^(2+) ions selectively as a fluorescence probe.The Fe-N-CQDs were synthesized by an efficient electrolysis of a carbon cloth electrode,which was coated with monoatomic ironanchored nitrogen-doped carbon(Fe-N-C).The obtained Fe-N-CQDs emitted blue fluorescence and possessed a quantum yield(QY)of 7.5%.An extremely wide linear relationship between the Cu^(2+) concentration and the fluorescence intensity was obtained in the range from 100 nmol L^(-1) to 1000 nmol L^(-1)(R^(2)=0.997),and the detection limit was calculated as 59 nmol L^(-1).Moreover,the Fe-N-CQDs demonstrated wide range pH compatibility between 2 and 13 due to the coordination between pyridine nitrogen and Fe^(3+),which dramatically reduced the affection of the protonation and deprotonation process between H^(+) and Fe-N-CQDs.It is notable that the Fe-N-CQDs exhibited a rapid response in Cu^(2+) detection,where stable quenching can be completed in 7 s.The mechanism of excellent selective detection of Cu^(2+) was revealed by energy level simulation that the LUMO level of Fe-N-CQDs(-4.37 eV)was close to the redox potential of Cu^(2+),thus facilitating the electron transport from Fe-N-CQDs to Cu^(2+).
