Carbon Nitride Materials as Efficient Catalyst Supports for Proton Exchange Membrane Water Electrolyzers

Sobrido, Ana Jorge; Dedigama, Ishanka; Miller, Thomas S.; Shearing, Paul R.; Brett, Dan J. L.; McMillan, Paul F.

doi:10.3390/nano8060432

“…Graphitic carbon nitride (g-C 3 N 4 ) has been demonstrated as a promising solar-to-fuel, metal-free, polymeric photocatalyst due to its suitable band structure, highly thermal and chemical stability, low cost and convenient preparation [ 4 , 5 , 6 ]. However, there are some intrinsic drawbacks to g-C 3 N 4 , such as its low electrical conductivity, insufficient light absorption, poor surface area and rapid recombination of photogenerated charge carriers [ 7 , 8 ]. Therefore, a great many strategies have been explored to improve its photocatalytic performance, including morphology design, elemental doping, heterojunction construction, nanocomposite hybridization and photosensitizer decoration [ 9 , 10 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Sun

¹

,

Liu

²

,

Feng

³

2021

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Graphitic carbon nitride (g-C3N4) has attracted much attention because of its potential for application in solar energy conservation. However, the photocatalytic activity of g-C3N4 is limited by the rapidly photogenerated carrier recombination and insufficient solar adsorption. Herein, fluorinated g-C3N4 (F-g-CN) nanosheets are synthesized through the reaction with F2/N2 mixed gas directly. The structural characterizations and theoretical calculations reveal that fluorination introduces N vacancy defects, structural distortion and covalent C-F bonds in the interstitial space simultaneously, which lead to mesopore formation, vacancy generation and electronic structure modification. Therefore, the photocatalytic activity of F-g-CN for H2 evolution under visible irradiation is 11.6 times higher than that of pristine g-C3N4 because of the enlarged specific area, enhanced light harvesting and accelerated photogenerated charge separation after fluorination. These results show that direct treatment with F2 gas is a feasible and promising strategy for modulating the texture and configuration of g-C3N4-based semiconductors to drastically enhance the photocatalytic H2 evolution process.

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“…[51]Ir 0.7 Ru 0.3 O x 1.8Pt/C0.51801.680 V (1 A cm −2 )spraying6.25Jorge et al . [52]gCNH-IrO21.2Pt/C41801.93 V (1 A cm −2 )spraying7.07this studyIrO 2 /Co 0.2 Sn 0.8 O 2 2.5Pt/C0.51801.776 V (1 A cm −2 )spraying3.65100180…”

Section: Resultsmentioning

confidence: 99%

Mesoporous Co _x Sn _{(1–
x
)} O ₂ as an efficient oxygen evolution catalyst support for SPE water electrolyzer

Chen

¹

,

Li

²

,

Lv

³

et al. 2019

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SPE water electrolysis is a promising method of hydrogen production owing to its multiple strengths, including its high efficiency, high product purity and excellent adaptability. However, the overpotential of the oxygen evolution reaction process and consumption of Ir during charging in SPE water electrolysis will inevitably result in large energy loss and then high cost. Under these circumstances, we propose a novel 40IrO 2 /Co x Sn (1− x ) O 2 ( x = 0.1, 0.2, 0.3) anode catalyst, where the Co x Sn (1− x ) O 2 support is synthesized by a hydrothermal method and IrO 2 is synthesized by a modified Adams fusion method. After modifying the component of Co x Sn (1− x ) O 2 , the 40IrO 2 /Co x Sn (1− x ) O 2 exhibits an increased specific surface area, electrical conductivity and surface active sites. Moreover, a single cell is fabricated by Pt/C as cathode catalyst, 40IrO 2 /Co x Sn (1− x ) O 2 as anode catalyst and Nafion 117 membrane as electrolyte. The 40IrO 2 /Co 0.2 Sn 0.8 O 2 exhibits the lowest overpotential (1.748 V at 1000 mA cm −2 ), and only 0.18 mV h −1 of voltage increased for 100 h durability test at 1000 mA cm −2 . Consequently, Co x Sn (1− x ) O 2 is a promising anode electrocatalyst support for an SPE water electrolyzer.

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“…Nevertheless, the usage of C-based materials is not only limited to the anode. A recent study shows that carbon nitride (C 3 N 4 ) resist the harsh conditions at the anode side and therefore can be used as the supporting material for OER catalysts, such as IrO 2 , hence to reduce the Ir content at the anode [163].…”

Section: Carbon-based Materialsmentioning

confidence: 99%

Earth-Abundant Electrocatalysts in Proton Exchange Membrane Electrolyzers

Sun

¹

,

Xu

²

,

Fleischer

³

et al. 2018

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In order to adopt water electrolyzers as a main hydrogen production system, it is critical to develop inexpensive and earth-abundant catalysts. Currently, both half-reactions in water splitting depend heavily on noble metal catalysts. This review discusses the proton exchange membrane (PEM) water electrolysis (WE) and the progress in replacing the noble-metal catalysts with earth-abundant ones. The efforts within this field for the discovery of efficient and stable earth-abundant catalysts (EACs) have increased exponentially the last few years. The development of EACs for the oxygen evolution reaction (OER) in acidic media is particularly important, as the only stable and efficient catalysts until now are noble-metal oxides, such as IrOx and RuOx. On the hydrogen evolution reaction (HER) side, there is significant progress on EACs under acidic conditions, but there are very few reports of these EACs employed in full PEM WE cells. These two main issues are reviewed, and we conclude with prospects for innovation in EACs for the OER in acidic environments, as well as with a critical assessment of the few full PEM WE cells assembled with EACs.

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Carbon Nitride Materials as Efficient Catalyst Supports for Proton Exchange Membrane Water Electrolyzers

Cited by 19 publications

References 55 publications

Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Mesoporous Co _x Sn _{(1–
x
)} O ₂ as an efficient oxygen evolution catalyst support for SPE water electrolyzer

Earth-Abundant Electrocatalysts in Proton Exchange Membrane Electrolyzers

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Carbon Nitride Materials as Efficient Catalyst Supports for Proton Exchange Membrane Water Electrolyzers

Cited by 19 publications

References 55 publications

Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Gas-Phase Fluorination of g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Mesoporous Co x Sn (1– x ) O 2 as an efficient oxygen evolution catalyst support for SPE water electrolyzer

Earth-Abundant Electrocatalysts in Proton Exchange Membrane Electrolyzers

Contact Info

Product

Resources

About

Mesoporous Co _x Sn _{(1–
x
)} O ₂ as an efficient oxygen evolution catalyst support for SPE water electrolyzer