Active Sites for Oxygen Reduction Reaction and the Reaction Mechanism in Carbon-Supported Hafnium Oxynitride

Chisaka, Mitsuharu; Suzuki, Yuta; Iijima, Tomohiro; Ishihara, Yuki; Inada, Ryoji; Sakurai, Yasuhisa

doi:10.1149/2.004201eel

Cited by 20 publications

(22 citation statements)

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“…[ 121 ] It is comparable to commercial Pt/C in terms of catalytic activity and outperforms Pt regarding long-term stability. Transition metal oxynitrides, including Ti, [ 168 ] Zr, [ 169 ] Hf [ 170 ] and Ta [ 171 ] monometallic oxynitrides, and bimetallic oxynitrides, have also been studied for ORR catalysis due to their high electric conductivity and corrosion resistance. Ohnishi et al [ 167 ] reported various monometallic nitrides (TaN, TiN, NbN, and Ta 3 N 5 ) wherein their ORR activities were compared via temperature-programmed desorption (TPD) spectra.…”

Section: Transition Metal Nitrides/oxynitrides/carbidesmentioning

confidence: 99%

“…They highlighted the synergistic effect of two nitrides with different characteristics. Transition metal oxynitrides, including Ti, Zr, Hf and Ta monometallic oxynitrides, and bimetallic oxynitrides, have also been studied for ORR catalysis due to their high electric conductivity and corrosion resistance . Ando et al demonstrated that active NH 3 ‐treated Co‐W/C is structurally oxynitride.…”

Section: Transition Metal Oxides/chalcogenides/nitrides/oxynitrides/cmentioning

confidence: 99%

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Non‐Pt Nanostructured Catalysts for Oxygen Reduction Reaction: Synthesis, Catalytic Activity and its Key Factors

Xia

Chen

et al. 2016

Advanced Energy Materials

168

107

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caused by electrochemical polarization, Ohmic polarization and mass transport polarization. [ 4 ] The electrochemical reaction occurring on the cathode is oxygen reduction reaction (ORR). It is kinetically much more sluggish as compared to anode reaction, thereby calling for effi cient ORR catalysts. [ 1 ] Basically for ORR catalysis there are two main pathways, i.e., direct 4e pathway (O 2 + 4H + + 4e − → 2H 2 O) and 2 by 2e pathway (O 2 + 2H + + 2e → H 2 O 2 , H 2 O 2 + 2H + + 2e → 2H 2 O), the latter of which ends up with H 2 O 2 generation in 2-electron pathway or H 2 O generation in 4-electron pathway, making the 4-electron pathway more efficient and desirable. [ 1,5 ] In the past few decades, Pt catalysts have been considered to be the best catalysts; however, typical problems facing Pt, including unsatisfactory long-term durability due to dissolution, methanol crossover and CO poisoning, are hindrances to mass application of PEMFC and make it a nontrivial issue to develop some novel cathode electrocatalysts. [ 6,7 ] Moreover, around half of the cost of PEMFC power system is the fuel cell stack cost, a large proportion of which stems from expensive Pt catalysts; unlike other stack components, Pt catalyst cost seems to be less affected by economies of sale due to the scarcity and increasing demand of Pt. [ 8 ] Many strategies have therefore been proposed to address these challenges. They can reasonably be classifi ed into two types, i.e., lowering the Pt concentration by mixing Pt with other metals to form Pt-based alloys [ 7,9 ] or Pt-skin/skeleton surface structures, [ 10,11 ] and developing non-Pt catalysts [ 12 ] or even metalfree catalysts. [ 13 ] Recently, a wide variety of non-Pt ORR catalysts have been intensively studied as substitutes for state-ofthe-art Pt or Pt-based catalysts. Monometallic catalysts such as Au, Ag with tunable particle size, morphology and preferential surface orientation have attracted growing attention due to their enhanced activities; in particular, monometallic catalysts supported on graphene or its derivatives are shown to have extraordinary catalytic performance and long-term durability since graphene, with its sp 2 -hybridized honeycomb structure, enhances mass transport and electron transfer, and the synergetic coupling between monometallic catalysts and graphene supports prevents the occurrence of particle dissolution and aggregation. [ 6,14 ] Similarly, metal chalcogenides grown on (heteroatom-doped) graphenes have noticeably higher ORR activities relative to unsupported counterparts due to the Pt-based electrocatalysts for the oxygen reduction reaction (ORR) are the topic of extensive and intensive research since a few decades. Nevertheless, the scarcity of these Pt-based electrocatalysts, their high cost and unsatisfactory durability are the primary hindrances to their further commercialization. In recent years, non-Pt electrocatalysts have garnered considerable interest as alternatives to Pt-based catalysts for the ORR. This review highlights the synthesis, catalyti...

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Section: Transition Metal Nitrides/oxynitrides/carbidesmentioning

confidence: 99%

Section: Transition Metal Oxides/chalcogenides/nitrides/oxynitrides/cmentioning

confidence: 99%

Non‐Pt Nanostructured Catalysts for Oxygen Reduction Reaction: Synthesis, Catalytic Activity and its Key Factors

Xia

Chen

et al. 2016

Advanced Energy Materials

168

107

View full text Add to dashboard Cite

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“…[1] . 以锆 [2][3][4][5][6] 、钽 [5][6][7][8][9][10] 、铌 [6] 、钛 [5,11] 和铪 [11][12][13] 的氧化物作为阴极氧还原催化剂的研究已见报道, 合成方法也多种多样. TiO 2 是一种前景广阔、研究广泛的光催化剂, 有关其合成、形貌及晶相控制、改性及与其他材料复合方面的研究已十分深入 [14,15] .…”

Section: Discussionunclassified

“…Groups 4 and 5 metal oxide compounds have been regarded as promising candidates for polymer electrolyte fuel cell (PEFC) cathode catalysts because they are insoluble in acid media [1]. The use of oxides of zirconium [2][3][4][5][6], tantalum [5][6][7][8][9][10], niobium [6], titanium [1,5], and hafnium [11][12][13] as cathode catalysts in oxygen reduction studies has been reported, with varied synthesis methods employed. In particular, TiO2 is a promising photocatalyst that has received widespread interest [14,15].…”

Section: Introductionmentioning

confidence: 99%

Pyrolyzed titanium dioxide/polyaniline as an efficient non-noble metal electrocatalyst for oxygen reduction reaction

Zou

Cheng

Wang

et al. 2015

Chinese Journal of Catalysis

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“…Thec atalytic activity of some metallic ceramics is similar to that of some noble metals [10] and some of them were found to be active not only for HER (e.g.M o 2 C, [11] Mo 2 N [12] and Co x N [13] )o rO ER (e.g. Ni x Na nd Fe x N, [13][14][15] Co x N [1] and Mn 3 N 2 [16] ), but also for the reverse electrochemical processes such as oxygen reduction reaction (ORR), the cathode reaction in the fuel cells [17][18][19] .Insome cases,however,the material is unstable or the syntheses require toxic ammonia flow, hindering the production on al arge scale.A mong metal nitrides,H f-based nitrides are among the least explored in ca-talysis and electrocatalysis.Sofar,only HfON has been tested with promising results towards ORR [19,20] and HER, [21] but not in OER. To the best of our knowledge,nostudies on hafnium nitride (HfN) have been reported.…”

Section: Introductionmentioning

confidence: 99%

HfN Nanoparticles: An Unexplored Catalyst for the Electrocatalytic Oxygen Evolution Reaction

et al. 2019

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Water electrolysis is one of the most promising methods to produce H 2 and O 2 as high potential fuels.Comparing the two half-reactions,the oxygen evolution reaction (OER) is the more difficult to be optimizedand still relies on expensive noble metal-based catalysts such as Ru or Ir.Inthis paper,we prepared nanoparticles of HfN and Hf 2 ON 2 and tested them for the OER for the first time.The HfN sample,i np articular, showed the highest activity,requiring an overpotential of only 358 mV at 10 mA cm À2 in Fe-free electrolyte and, abovea ll, exhibiting long-term stability.T his result places this system amongst one of the most promising catalysts for OER tested to date,i nt erms of sustainability,a ctivity and stability.T he prepared nanoparticles are small (less than 15 nm in diameter), well-defined in shape and crystalline,a nd were characterised before and after electrochemical testing also via electron microscopy(EM), powder X-ray diffraction (PXRD) and X-ray photoelectron spectroscopy(XPS). Scheme 1. The two half-reactions for the water-splitting process:H 2 is produced at the cathode (HER) and O 2 at the anode (OER). [1] Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under https://doi.

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Active Sites for Oxygen Reduction Reaction and the Reaction Mechanism in Carbon-Supported Hafnium Oxynitride

Cited by 20 publications

References 0 publications

Non‐Pt Nanostructured Catalysts for Oxygen Reduction Reaction: Synthesis, Catalytic Activity and its Key Factors

Non‐Pt Nanostructured Catalysts for Oxygen Reduction Reaction: Synthesis, Catalytic Activity and its Key Factors

Pyrolyzed titanium dioxide/polyaniline as an efficient non-noble metal electrocatalyst for oxygen reduction reaction

HfN Nanoparticles: An Unexplored Catalyst for the Electrocatalytic Oxygen Evolution Reaction

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