Aniline,pyrrole and phenanthroline,which have different nitrogen compositions,are used as carbon precursors to synthesize nitrogen-doped ordered mesoporous carbons(NOMCs) by the nanocasting method.The effect of the ...Aniline,pyrrole and phenanthroline,which have different nitrogen compositions,are used as carbon precursors to synthesize nitrogen-doped ordered mesoporous carbons(NOMCs) by the nanocasting method.The effect of the precursor on the resultant NOMC is extensively investigated by nitrogen adsorption-desorption measurements,scanning electron microscopy,X-ray photoelectron spectroscopy(XPS),cyclic voltammetry and rotating ring-disk electrode measurements.Salient findings are as follows.First,the precursor has a significant influence on the specific surface area and textural properties.The NOMC materials derived from pyrrole(C-PY-900:765 m^2/) and phenanthroline(C-Phen-900:746 m^2/) exhibit higher specific surface areas than the aniline analog(C-PA-900:569 m^2/).Second,the XPS results indicate that the total nitrogen content(ca.3.1–3.3 at%) is similar for the three carbon sources,except for a slight difference in the nitrogen configuration.Furthermore,the content of the nitrogen-activated carbon atoms is found to closely depend on the precursor,which is the highest for the phenanthroline-derived carbon.Third,the electrochemical results reveal that the electrocatalytic activity follows in the order C-PA-900 C-PY-900 C-Phen-900,confirming that the nitrogen-activated carbon atoms are the active sites for the oxygen reduction reaction(ORR).In summary,the precursor has considerable influence on the composition and textural properties of the NOMC materials,of which the ORR electrocatalytic activity can be enhanced through optimization of the NOMCs.展开更多
Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is...Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is two times higher than that of 25 nm,confirming that the intrinsic activity does depend on the size of the nanoparticles.It is further found that the adsorbed ligand does yield effect on electrocatalysis,and the adsorption strength follows the order of PVP>CTAB>citrate.This work is of significance to understand the nature of the ORR’s electrocatalysis at the level of an individual entity,which makes the structure-activity correlation in a more reliable way.展开更多
Polymer electrolyte membrane fuel cells(PEMFCs), as an energy conversion technology, have attracted extensive attention due to their high conversion efficiency, low emission, high energy density,and fast fuel charging...Polymer electrolyte membrane fuel cells(PEMFCs), as an energy conversion technology, have attracted extensive attention due to their high conversion efficiency, low emission, high energy density,and fast fuel charging [1,2]. Pt-based catalysts have been acknowledged to be the most effective catalyst for the oxygen reduction reaction(ORR) [3–5]. However, both the source scarcity and high cost of Pt severely hinder the commercial application of the PEMFCs [1,6,7].展开更多
Carbon-supported PtPdRuIr, Pd@PtRuIr, PtPd@PtRuIr, and PtPdRu@PtRuIr catalysts were prepared by a colloidal method and their catalytic activities to the methanol oxidation reaction in the acidic media were extensively...Carbon-supported PtPdRuIr, Pd@PtRuIr, PtPd@PtRuIr, and PtPdRu@PtRuIr catalysts were prepared by a colloidal method and their catalytic activities to the methanol oxidation reaction in the acidic media were extensively investigated at room temperature. The catalysts were characterized by transmission electron microscopy and X-ray diffraction techniques, and their electrochemical behavior was evaluated by the cyclic voltammetry. The PtPdRu@PtRuIr/C catalyst is found to yield much higher electrocatalytic activity than the other ones and the commercial catalyst. For example, the Pt metal mass-specific activity of this PtPdRu@PtRuIr/C(Pt content 10 wt%,1.7 mAácm-2ámg-1) electrocatalyst is *3-fold higher than that of the commercial JM 40 % Pt/C(0.6 mAácm-2ámg-1)electrocatalysts, and the If/Ib ratio of PtPdRu@PtRuIr/C is1.6, which is higher than that of the JM 40 % Pt/C(0.9). The improvement may result from the high dispersion of the active metal catalyst and the synergistic effect between the PtRuIr and PtPdRu layers. It is thus concluded that the pseudo-core-shell structure could significantly improve the methanol electro-oxidation activity and CO tolerance of the electrocatalyst.展开更多
基金supported by the National Natural Science Foundation of China(21476087,21576101)the Innovation Project of Guangdong Department of Education(2014KTSCX016)+1 种基金the Science&Technology Research Project of Guangdong Province(2013B010405005,2014A010105041)the Fundamental Research Funds for the Central Universities~~
文摘Aniline,pyrrole and phenanthroline,which have different nitrogen compositions,are used as carbon precursors to synthesize nitrogen-doped ordered mesoporous carbons(NOMCs) by the nanocasting method.The effect of the precursor on the resultant NOMC is extensively investigated by nitrogen adsorption-desorption measurements,scanning electron microscopy,X-ray photoelectron spectroscopy(XPS),cyclic voltammetry and rotating ring-disk electrode measurements.Salient findings are as follows.First,the precursor has a significant influence on the specific surface area and textural properties.The NOMC materials derived from pyrrole(C-PY-900:765 m^2/) and phenanthroline(C-Phen-900:746 m^2/) exhibit higher specific surface areas than the aniline analog(C-PA-900:569 m^2/).Second,the XPS results indicate that the total nitrogen content(ca.3.1–3.3 at%) is similar for the three carbon sources,except for a slight difference in the nitrogen configuration.Furthermore,the content of the nitrogen-activated carbon atoms is found to closely depend on the precursor,which is the highest for the phenanthroline-derived carbon.Third,the electrochemical results reveal that the electrocatalytic activity follows in the order C-PA-900 C-PY-900 C-Phen-900,confirming that the nitrogen-activated carbon atoms are the active sites for the oxygen reduction reaction(ORR).In summary,the precursor has considerable influence on the composition and textural properties of the NOMC materials,of which the ORR electrocatalytic activity can be enhanced through optimization of the NOMCs.
基金jointly supported by the National Natural Science Foundation of China(Nos.21903026,21975081,21975079,21676106)Science and Technology Program of Guangdong Province(2017A050506015)+2 种基金Science and Technology Program of Guangzhou(201704030065)China Postdoctoral Science Foundation(2019M652877)the Fundamental Research Funds for the Central Universities。
文摘Nanocollision electrochemistry is employed to evaluate the ORR’s activity of one single Pt nanoparticle,the effect of the size and ligand is investigated.The size-normalized activity of the Pt nanoparticle of 4 nm is two times higher than that of 25 nm,confirming that the intrinsic activity does depend on the size of the nanoparticles.It is further found that the adsorbed ligand does yield effect on electrocatalysis,and the adsorption strength follows the order of PVP>CTAB>citrate.This work is of significance to understand the nature of the ORR’s electrocatalysis at the level of an individual entity,which makes the structure-activity correlation in a more reliable way.
基金supported by the National Natural Science Foundation of China (Nos. 21676106 and 21576101)Science and Technology Program of Guangzhou (201704030065)+1 种基金Science and Technology Program of Guangdong (2017A050506015)the Fundamental Research Funds for the Central Universities
文摘Polymer electrolyte membrane fuel cells(PEMFCs), as an energy conversion technology, have attracted extensive attention due to their high conversion efficiency, low emission, high energy density,and fast fuel charging [1,2]. Pt-based catalysts have been acknowledged to be the most effective catalyst for the oxygen reduction reaction(ORR) [3–5]. However, both the source scarcity and high cost of Pt severely hinder the commercial application of the PEMFCs [1,6,7].
基金financially supported by the National Natural Scientific Foundation of China (Nos. 20673040 and20876062)Guangdong Provincial Scientific Foundation (Nos. 36055 and S2012040007383)the Key Laboratory of Fuel Cell Technology of Guangdong Province (No. 201112)
文摘Carbon-supported PtPdRuIr, Pd@PtRuIr, PtPd@PtRuIr, and PtPdRu@PtRuIr catalysts were prepared by a colloidal method and their catalytic activities to the methanol oxidation reaction in the acidic media were extensively investigated at room temperature. The catalysts were characterized by transmission electron microscopy and X-ray diffraction techniques, and their electrochemical behavior was evaluated by the cyclic voltammetry. The PtPdRu@PtRuIr/C catalyst is found to yield much higher electrocatalytic activity than the other ones and the commercial catalyst. For example, the Pt metal mass-specific activity of this PtPdRu@PtRuIr/C(Pt content 10 wt%,1.7 mAácm-2ámg-1) electrocatalyst is *3-fold higher than that of the commercial JM 40 % Pt/C(0.6 mAácm-2ámg-1)electrocatalysts, and the If/Ib ratio of PtPdRu@PtRuIr/C is1.6, which is higher than that of the JM 40 % Pt/C(0.9). The improvement may result from the high dispersion of the active metal catalyst and the synergistic effect between the PtRuIr and PtPdRu layers. It is thus concluded that the pseudo-core-shell structure could significantly improve the methanol electro-oxidation activity and CO tolerance of the electrocatalyst.