Limits...
Novel VN/C nanocomposites as methanol-tolerant oxygen reduction electrocatalyst in alkaline electrolyte.

Huang K, Bi K, Liang C, Lin S, Zhang R, Wang WJ, Tang HL, Lei M - Sci Rep (2015)

Bottom Line: A novel VN/C nanostructure consisting of VN nanoparticles and graphite-dominant carbon layers is synthesized by nitridation of V2O5 using melamine as reductant under inert atmosphere.Moreover, the electrocatalytic performance of VN/C towards oxygen reduction reaction (ORR) in alkaline electrolyte is fascinating.The results show that VN/C has a considerable ORR activity, including a 75 percent value of the diffusion-limited current density and a 0.11 V smaller value about the onset potential with respect to Pt/C catalyst.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Information Photonics and Optical Communications &School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.

ABSTRACT
A novel VN/C nanostructure consisting of VN nanoparticles and graphite-dominant carbon layers is synthesized by nitridation of V2O5 using melamine as reductant under inert atmosphere. High crystalline VN nanoparticles are observed to be uniformly distributed in carbon layers with an average size of ca13.45 nm. Moreover, the electrocatalytic performance of VN/C towards oxygen reduction reaction (ORR) in alkaline electrolyte is fascinating. The results show that VN/C has a considerable ORR activity, including a 75 percent value of the diffusion-limited current density and a 0.11 V smaller value about the onset potential with respect to Pt/C catalyst. Moreover, the excellent methanol-tolerance performance of VN/C has also been verified with 3 M methanol. Combined with the competitive prices, this VN/C nanocomposite can serve as an appropriate non-precious methanol-tolerant ORR catalyst for alkaline fuel cells.

No MeSH data available.


Related in: MedlinePlus

XPS spectra of the surface of VN/C nanocomposite.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4477409&req=5

f7: XPS spectra of the surface of VN/C nanocomposite.

Mentions: It is because that the ORR process is a function of the consumption of oxygen at the surface of a catalyst, the surface chemical states are closely related to its activity and durability. XPS spectra of VN/C catalyst are further studied to feature the surface of VN/C nanocomposite in Fig. 7, it can be seen that the surface of VN/C mainly consists of V, N, O, and C species elements from the survey spectrum. The appearance of O species seems to be unanticipated as no O element was detected by EDS analysis, the most possible reasons are that O element is relative limited and mainly exists in the surface of VN/C sample which is overlapped by high-intensity V peak and thus beyond the detection precision of EDS42. Figure 7B shows the high-resolution XPS spectra of O 1 s and V 2p, indicating the presence of an oxide layer on the surface of VN. The peaks at 532.2 and 529.9 eV of O1s can be attributed to lattice oxygen in a metal oxide and adsorbed hydroxyl oxygen (OH−) on the surface of VN/C, respectively434445. The V (2p3/2) and V (2p1/2) peaks centered at 513.6 and 521.1 eV belong to vanadium in the VN crystalline while the other two peaks at 515.3 and 522.6 eV can be assigned to oxidation states of vanadium in surface oxynitrides VOxNy owing to the passivation of VN in air as a protective oxide layer of the surface to avoid the strong oxidation454647. Figure 7C shows the N 1 s spectrum of VN/C, the peak at 397.4 eV is the typical characteristic of metal nitride (VN in this situation) while the peak at 400.2 eV can be generally attributed to the adsorbed NH3 at the surface of VN/C deriving from the decomposition of melamine at high temperature304849. Moreover, the C1s profile is composed of a single symmetric peak as shown in Fig. 7D, which means that the C element in VN/C is just carbon and no carbides or carbonitrides exists in VN/C. Thus, the core-shell structure as well as the nanocrystallization of VN particles is believed to be favorable to enhance ORR electrocatalytic activity similar to the report by Bao and his co-workers50, while the VOxNy layer and graphitic layers on the surface of VN nanoparticles benefit the tolerance of methanol.


Novel VN/C nanocomposites as methanol-tolerant oxygen reduction electrocatalyst in alkaline electrolyte.

Huang K, Bi K, Liang C, Lin S, Zhang R, Wang WJ, Tang HL, Lei M - Sci Rep (2015)

XPS spectra of the surface of VN/C nanocomposite.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4477409&req=5

f7: XPS spectra of the surface of VN/C nanocomposite.
Mentions: It is because that the ORR process is a function of the consumption of oxygen at the surface of a catalyst, the surface chemical states are closely related to its activity and durability. XPS spectra of VN/C catalyst are further studied to feature the surface of VN/C nanocomposite in Fig. 7, it can be seen that the surface of VN/C mainly consists of V, N, O, and C species elements from the survey spectrum. The appearance of O species seems to be unanticipated as no O element was detected by EDS analysis, the most possible reasons are that O element is relative limited and mainly exists in the surface of VN/C sample which is overlapped by high-intensity V peak and thus beyond the detection precision of EDS42. Figure 7B shows the high-resolution XPS spectra of O 1 s and V 2p, indicating the presence of an oxide layer on the surface of VN. The peaks at 532.2 and 529.9 eV of O1s can be attributed to lattice oxygen in a metal oxide and adsorbed hydroxyl oxygen (OH−) on the surface of VN/C, respectively434445. The V (2p3/2) and V (2p1/2) peaks centered at 513.6 and 521.1 eV belong to vanadium in the VN crystalline while the other two peaks at 515.3 and 522.6 eV can be assigned to oxidation states of vanadium in surface oxynitrides VOxNy owing to the passivation of VN in air as a protective oxide layer of the surface to avoid the strong oxidation454647. Figure 7C shows the N 1 s spectrum of VN/C, the peak at 397.4 eV is the typical characteristic of metal nitride (VN in this situation) while the peak at 400.2 eV can be generally attributed to the adsorbed NH3 at the surface of VN/C deriving from the decomposition of melamine at high temperature304849. Moreover, the C1s profile is composed of a single symmetric peak as shown in Fig. 7D, which means that the C element in VN/C is just carbon and no carbides or carbonitrides exists in VN/C. Thus, the core-shell structure as well as the nanocrystallization of VN particles is believed to be favorable to enhance ORR electrocatalytic activity similar to the report by Bao and his co-workers50, while the VOxNy layer and graphitic layers on the surface of VN nanoparticles benefit the tolerance of methanol.

Bottom Line: A novel VN/C nanostructure consisting of VN nanoparticles and graphite-dominant carbon layers is synthesized by nitridation of V2O5 using melamine as reductant under inert atmosphere.Moreover, the electrocatalytic performance of VN/C towards oxygen reduction reaction (ORR) in alkaline electrolyte is fascinating.The results show that VN/C has a considerable ORR activity, including a 75 percent value of the diffusion-limited current density and a 0.11 V smaller value about the onset potential with respect to Pt/C catalyst.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Information Photonics and Optical Communications &School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China.

ABSTRACT
A novel VN/C nanostructure consisting of VN nanoparticles and graphite-dominant carbon layers is synthesized by nitridation of V2O5 using melamine as reductant under inert atmosphere. High crystalline VN nanoparticles are observed to be uniformly distributed in carbon layers with an average size of ca13.45 nm. Moreover, the electrocatalytic performance of VN/C towards oxygen reduction reaction (ORR) in alkaline electrolyte is fascinating. The results show that VN/C has a considerable ORR activity, including a 75 percent value of the diffusion-limited current density and a 0.11 V smaller value about the onset potential with respect to Pt/C catalyst. Moreover, the excellent methanol-tolerance performance of VN/C has also been verified with 3 M methanol. Combined with the competitive prices, this VN/C nanocomposite can serve as an appropriate non-precious methanol-tolerant ORR catalyst for alkaline fuel cells.

No MeSH data available.


Related in: MedlinePlus