Ultrathin Graphitic C<sub>3</sub>N<sub>4</sub> Nanosheets/Graphene Composites: Efficient Organic Electrocatalyst for Oxygen Evolution Reaction

Tian, Jingqi; Liu, Qian; Asiri, Abdullah M.; Alamry, Khalid A.; Sun, Xuping

doi:10.1002/cssc.201402118

Cited by 236 publications

(149 citation statements)

References 80 publications

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“…This value is lower than that of OGF electrode (0.410 V), and also much lower than those of carbon fi lms reported previously, such as N, O-dual doped graphene-CNT hydrogel fi lm (NG/CNT, ≈0.484 V), [ 21 ] oxidized carbon cloth (OCC-8, 0.477 V), [ 22 ] 3D hybrid fi lm of porous N-doped graphene-NiCo 2 O 4 (PNG-NiCo,0.432 V), [ 24 ] and 3D N-doped carbon fi lm assembled by graphene and graphitic carbon nitride (G-C 3 N 4 , 0.415 V) [ 25 ] (Figure 3 F and Table S4, Supporting Information). The electrocatalytic activity of NSGF electrode is also superior to those of previously reported metal-free catalysts, including mildly oxidized multiwalled CNTs that activated by hydrothermal and electrochemical treatments (echoMWCNTs, 0.450 V), [ 17 ] N-doped graphene/single-walled CNT hybrid (NGSH, 0.400 V), [ 50 ] graphitic carbon nitride/graphene composites (g-C 3 N 4 /graphene, 0.539 V), [ 51 ] thermally reduced graphene oxide/N-doped CNTs (TRGO/NCNT, 0.505 V), [ 52 ] 3D Ni foam/porous carbon/anodized Ni electrode (3D-NF/PC/ AN, 0.520 V), [ 23 ] N-doped coaxial carbon nanocables (CNT@ NCNT, 0.527 V), [ 53 ] and even comparable to those of N-doped carbon material (N/C, 0.380 V) [ 20 ] and g-C 3 N 4 nanosheets-CNTs composite (g-C 3 N 4 NS-CNT, 0.370 V) [ 54 ] (Table S4 wileyonlinelibrary.com is a pure carbonaceous catalyst containing only C, N, O, and S nonmetallic elements, without blending other catalysts such as widely used g-C 3 N 4 , or metal species.…”

Section: The Electrocatalytic Performances For Oermentioning

confidence: 86%

Nitrogen and Sulfur Codoped Graphite Foam as a Self‐Supported Metal‐Free Electrocatalytic Electrode for Water Oxidation

Zhang

et al. 2015

Advanced Energy Materials

162

111

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positively charged. They can adsorb OH − ions with charge transfer to decrease the activation energy of OER, and support the recombination of OER intermediates (e.g., O 2− and O 2 2− ) to form oxygen gas during OER process. [ 17,21,22 ] Furthermore, the nitrogen species (e.g., pyridinic N atoms) can also participate in the electrocatalytic reaction. [ 20 ] Consequently, the carbon materials doped with N atoms or containing oxygenated groups can remarkably accelerate OER process, and they are expected to be effective substitutions of metal catalysts.Conversely, the reported OER electrocatalysts usually were powders; thus they have to be anchored onto glassy carbon electrodes or other conductive planar electrodes (e.g., carbon cloth) with polymeric binders for practical applications. Unfortunately, in these cases, the surfaces of electrocatalysts were partly inaccessible to reactants, and the 2D substrates are not suitable for desorption of O 2 bubbles, weakening the activity and restricting the recovery of active sites of OER catalysts. To overcome these problems, 3D structured electrodes with nickel foams or porous carbon hydrogel fi lms have been developed to immobilize catalysts. [ 21,[23][24][25][26] The high macroporosity of nickel foam can greatly increase the accessible specifi c surface areas of loaded catalysts, and facilitate the removal of gases. [ 23 ] However, the intrinsic instability of nickel decreased the long-term durability of these catalysts. Furthermore, the weak contacts between catalysts and nickel substrate frequently led to the releasing of catalysts during oxygen generation reaction. [ 21 ] The OER electrocatalysts with carbon hydrogel fi lms were mainly explored by Qiao's group. [ 21,[24][25][26] These 3D self-supported frameworks avoid using current collectors and polymeric binders (e.g., nafi on or polytetrafl uoroethylene), and the catalysts exhibited excellent activities. However, the hydrogel fi lms were prepared from chemical converted graphene (CCG) sheets by fi ltration. The preparation of CCG sheets usually involves a multistep complicated process, and using large amounts of acids, oxidants, and reducing agents. Moreover, the as-obtained CCG fi lms (without adding conductive additives or annealing treatment) have relatively low conductivities and brittle mechanical properties, possibly resulting in high overpotential and poor long-term stability.Commercial graphite foils (GFLs) are usually made of exfoliated graphite fl akes. They are cheap, available in large areas, fl exible, highly conductive, and thermally stable. Furthermore, they compose of nearly only carbon atoms without anyThe oxidation of water to produce oxygen gas is related to a variety of energy storage systems. Thus, the development of effi cient, cheap, durable, and scalable electrocatalysts for oxygen evolution reaction (OER) is of great importance. Here, a high-performance OER catalyst, nitrogen and sulfur codoped graphite foam (NSGF) is reported. This NSGF is prepared from commercial graphite foil and directly...

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Section: The Electrocatalytic Performances For Oermentioning

confidence: 86%

Nitrogen and Sulfur Codoped Graphite Foam as a Self‐Supported Metal‐Free Electrocatalytic Electrode for Water Oxidation

Zhang

et al. 2015

Advanced Energy Materials

162

111

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“…In particular, due to many advantages of easy operation, low-cost, environmental benignity, and no reason for interfacial defects, liquid-phase exfoliation, usually in conjunction with ultrasonic treatment has been intensively explored for producing ultrathin GCNNs by delaminating bulk GCN [28,31,32]. However, the obtained GCNNs usually have a thickness larger than 2 nm (> 5 layers) [30,33].…”

Section: Introductionmentioning

confidence: 99%

Reduced-sized monolayer carbon nitride nanosheets for highly improved photoresponse for cell imaging and photocatalysis

Liang

Bai

et al. 2016

Sci. China Mater.

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Two-dimensional graphitic carbon nitride (g-C3N4) nanosheets (GCNNs) have been considered as an attractive metal-free semiconductor because of their superior catalytic, optical, and electronic properties. However, it is still challenging to prepare monolayer GCNNs with a reduced lateral size in nanoscale. Herein, a highly efficient ultrasonic technique was used to prepare nanosized monolayer graphitic carbon nitride nanosheets (NMGCNs) with a thickness of around 0.6 nm and an average lateral size of about 55 nm. With a reduced lateral size yet monolayer thickness, NMGCNs show unique photo-responsive properties as compared to both large-sized GCNNs and GCN quantum dots. A dispersion of NMGCNs in water has good stability and exhibits strong blue fluorescence with a high quantum yield of 32%, showing good biocompatibility for cell imaging. Besides, compared to the multilayer GCNNs, NMGCNs show a highly improved photocatalysis under visible light irradiation. Overall, NMGCNs, characterized with monolayer and nanosized lateral dimension, fill the gap between large size (very high aspect ratio) and quantum dot-like counterparts, and show great potential applications as sensors, photo-related and electronic devices.

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“…[11][12][13][14][15] It is also well-known that the electrocatalytic performance is determined by catalyst structure and accessibility of active sites. It is of significant importance to maximize the electrochemical surface area to better facilitate the transport of reactants (OH − and O 2 ), and therefore enhance catalytic activity.…”

mentioning

confidence: 99%

Surface‐Modified Porous Carbon Nitride Composites as Highly Efficient Electrocatalyst for Zn‐Air Batteries

Niu

Marcus

et al. 2017

Advanced Energy Materials

137

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efficient and earth-abundant catalysts have been successfully developed including nitrogen-doped carbon materials that possess promising electrocatalytic performance for ORR and OER. [6][7][8][9][10] However, it remains challenging for nitrogen-doped carbon materials to achieve competitive performance to precious metal catalysts due to low nitrogen concentration.Graphitic carbon nitrides (g-C 3 N 4 ) have shown promising performance to replace nitrogen-doped carbon as a highly efficient catalyst, owing to its ultrahigh nitrogen content (theoretically estimated to be ≈60%) and easily tailored structure. [11][12][13][14][15] It is also well-known that the electrocatalytic performance is determined by catalyst structure and accessibility of active sites. It is of significant importance to maximize the electrochemical surface area to better facilitate the transport of reactants (OH − and O 2 ), and therefore enhance catalytic activity. [16][17][18] For this aim, various methods have been reported in preparation of porous g-C 3 N 4 . Conventionally, rigid templates (SiO 2 , Al 2 O 3 , and ZnO) are used to fabricate porous g-C 3 N 4 , [19,20] which can effectively improve accessibility and catalytic activity of g-C 3 N 4 . However, these rigid template-based synthesis methods are complicated, involving several steps such as template formation, template dispersion, template removal, and catalyst purification. These time-consuming processes increase the fabrication cost and can even damage the g-C 3 N 4 active sites during template removal by the use of strong acidic or basic etching. Addressing these challenges will require facile and strategic developments to synthesize porous g-C 3 N 4 without using templates.Herein, we developed a top-down and template-free strategy for the fabrication of porous g-C 3 N 4 (PCN) by controlled pyrolysis of Co 2+ /melamine networks in O 2 atmosphere. After mixing PCN with graphene oxide (GO) and thermal treating in sulfur atmosphere, CoS x @PCN/rGO catalyst was synthesized. The developed CoS x @PCN/rGO catalyst exhibited outstanding electrocatalytic activity and stability toward both OER and ORR. The CoS x @PCN/rGO also showed long cyclability as an air electrode in a zinc-air battery system, outperforming Pt and other precious metal electrocatalysts. The remarkable electrocatalytic performance of CoS x @PCN/rGO is attributed to the internally accessible nitrogen sites and the facilitated transport of intermediates in the porous structure.A typical synthesis route of PCN is schematically depicted in Figure 1a: First, cobalt(II) nitrate hexahydrate was mixed with Porous carbon nitride (PCN) composites are fabricated using a top-down strategy, followed by additions of graphene and CoS x nanoparticles. This subsequently enhances conductivity and catalytic activity of PCN (abbreviated as CoS x @PCN/rGO) and is achieved by one-step sulfuration of PCN/ graphene oxides (GO) composite materials. As a result, the as-prepared CoS x @PCN/rGO catalysts display excellent activity and stability towa...

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Ultrathin Graphitic C₃N₄ Nanosheets/Graphene Composites: Efficient Organic Electrocatalyst for Oxygen Evolution Reaction

Cited by 236 publications

References 80 publications

Nitrogen and Sulfur Codoped Graphite Foam as a Self‐Supported Metal‐Free Electrocatalytic Electrode for Water Oxidation

Nitrogen and Sulfur Codoped Graphite Foam as a Self‐Supported Metal‐Free Electrocatalytic Electrode for Water Oxidation

Reduced-sized monolayer carbon nitride nanosheets for highly improved photoresponse for cell imaging and photocatalysis

Surface‐Modified Porous Carbon Nitride Composites as Highly Efficient Electrocatalyst for Zn‐Air Batteries

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Ultrathin Graphitic C3N4 Nanosheets/Graphene Composites: Efficient Organic Electrocatalyst for Oxygen Evolution Reaction

Cited by 236 publications

References 80 publications

Nitrogen and Sulfur Codoped Graphite Foam as a Self‐Supported Metal‐Free Electrocatalytic Electrode for Water Oxidation

Nitrogen and Sulfur Codoped Graphite Foam as a Self‐Supported Metal‐Free Electrocatalytic Electrode for Water Oxidation

Reduced-sized monolayer carbon nitride nanosheets for highly improved photoresponse for cell imaging and photocatalysis

Surface‐Modified Porous Carbon Nitride Composites as Highly Efficient Electrocatalyst for Zn‐Air Batteries

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Ultrathin Graphitic C₃N₄ Nanosheets/Graphene Composites: Efficient Organic Electrocatalyst for Oxygen Evolution Reaction