Titanium Nitride Nanoparticle Electrocatalysts for Oxygen Reduction Reaction in Alkaline Solution

Abstract

KAUST RepositoryMonodispersed TiN nanoparticles with a narrow size distribution (7-23 nm) were synthesized using mesoporous graphitic (mpg)-C 3 N 4 templates with different pore sizes. The nano-materials were examined as electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The TiN nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 sorption, transmission electron microscopy (TEM), and C-H-N elemental analysis. The ORR current increased as the TiN particle size decreased, and hence the surface area of TiN nanoparticles reactive to ORR increased. Rotating ring disk electrode (RRDE) measurements revealed that the ORR on TiN surfaces proceeded mainly via a two-electron pathway, producing H 2 O 2 as the main product. The oxygen reduction reaction (ORR) is one of the important electrocatalytic reactions for energy conversion in both acidic and alkaline media. [1][2][3][4][5][6] In polymer electrolyte fuel cells (PEFCs), the performance of the cathode for ORR is still the primary limitation on overall PEFC efficiency. An improved understanding of ORR electrocatalysis has paved the way for the development of cathodes for metal-air batteries.1,2 In particular, the lithium-air battery, one of the most promising among high-power secondary batteries, is expected to be commercialized in next-generation devices.12 At the cathodes of the current standard configuration, ORR takes place in an alkaline environment. Thus, ORR experiments are worth examining in both acidic and alkaline media.We have demonstrated that oxynitrides of group IV and V transition metals, when synthesized at the nanometer scale, show high electrocatalytic performance for ORR and high stability in acidic media. [13][14][15][16][17] One of advantages of group IV and V transition metals is their abundance on the earth rather than platinum group metals. Among these catalysts, titanium nitride (TiN) nanoparticles prepared using mesoporous graphitic (mpg)-C 3 N 4 templates have been found to be active. [15][16][17] Our studies have led us to conclude that TiN surfaces are at least partially oxidized once they are exposed to air and that the active sites could be oxygen vacancies or defect sites, which presumably facilitate the adsorption of molecular oxygen. 17In this study, we prepared mono-dispersed TiN nanoparticles of varying size by utilizing the varied pore size of mpg-C 3 N 4 , which reflects the original colloidal silica particle size. The TiN nanoparticles were tested for ORR in an alkaline medium. It was found that TiN nanoparticles showed a relatively high performance for ORR but led to two-electron pathways, generating H 2 O 2 as the primary product, which behaves similarly to a carbon electrode. ExperimentalCatalyst synthesis.-TiN nanoparticles were prepared using mpg-C 3 N 4 templates, by a process described elsewhere.15-20 Nanoparticles of varying size were obtained through the use of mpg-C 3 N 4 with different pore sizes. Three kinds of aqueous silica solutions, viz. LU-DOX ...

Effect of nano‐titanium nitride on thermal insulating and flame‐retardant performances of phenolic foam

“…Remarkably, there are five peaks at 36.88, 42.88, 62.18, 74.38, and 78.28 appeared in the PFTNs' spectra, which are attributed to the characteristic diffraction peaks of TiN. 42,43 Moreover, the peaks' intensities increase with the increasing content of TiN nanoparticles, confirming that TiN nanoparticles have completely incorporated into the PR matrix. Additionally, by introducing the TiN nanoparticles, the color of the PFTNs appears as light black and it gradually turns darker as the content of the nanoparticles increased.…”

Electrodeposited Ultrafine TaOx/CB Catalysts for PEFC Cathode Application: Their Oxygen Reduction Reaction Kinetics

“…The disk electrode (4.0 mm diameter) was cathodically swept at a scan rate of 5 mV s À1 , and a constant potential of 1.2 V RHE was applied on the Pt ring electrode (5.0 mm inner diameter; 7.0 mm outer diameter). The H 2 O 2 production was determined by the following equation [26]:…”

Preparation of fibrous titania oxynitride – carbon catalyst and oxygen reduction reaction analysis in both acidic and alkaline media

“…In Fig. 4, the solid [28], and found an onset potential of 0.85 V vs. RHE for the prepared TiN nanoparticles, although commercial TiN (>100 nm in size) did not exhibit activity. To the best of our knowledge, the number of ORR studies for titania analogs in alkaline versus acidic media is limited, and studies concerned with kinetics and mechanism are especially rare.…”