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Carbon-based electrocatalysts for advanced energy conversion and storage.

Zhang J, Xia Z, Dai L - Sci Adv (2015)

Bottom Line: Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries.Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries.We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance.

View Article: PubMed Central - PubMed

Affiliation: Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.

ABSTRACT
Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance.

No MeSH data available.


Related in: MedlinePlus

Performance of rechargeable Zn-air batteries.(A) Discharge/charge cycling curves of a two-electrode rechargeable Zn-air battery at a current density of 2 mA cm−2 using the NPMC-1000 (pyrolysis at 1000°C) air electrode. Three-electrode Zn-air batteries. (B) Schematic illustration for the basic configuration of a three-electrode Zn-air battery by coupling a Zn electrode with two air electrodes to separate ORR and OER. The enlarged parts illustrate the porous structures of the air electrodes, which facilitates the gas exchange. (C) Charge and discharge polarization curves of three-electrode Zn-air batteries using the NPMC-1000, NPMC-1100, or commercial Pt/C catalyst as both of the air electrodes, along with the corresponding curve (that is, Pt/C + RuO2) for the three-electrode Zn-air battery with Pt/C and RuO2 nanoparticles as each of the air electrodes, respectively. (D) Discharge/charge cycling curves of a three-electrode Zn-air battery using NPMC-1000 as air electrodes (0.5 mg cm−2 for ORR and 1.5 mg cm−2 for OER) at a current density of 2 mA cm−2. [From J. Zhang, Z. Zhao, Z. Xia, L. Dai, A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions. Nat. Nanotechnol.10, 444–452 (2015). Reprinted with permission from the Nature Publishing Group.]
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Figure 11: Performance of rechargeable Zn-air batteries.(A) Discharge/charge cycling curves of a two-electrode rechargeable Zn-air battery at a current density of 2 mA cm−2 using the NPMC-1000 (pyrolysis at 1000°C) air electrode. Three-electrode Zn-air batteries. (B) Schematic illustration for the basic configuration of a three-electrode Zn-air battery by coupling a Zn electrode with two air electrodes to separate ORR and OER. The enlarged parts illustrate the porous structures of the air electrodes, which facilitates the gas exchange. (C) Charge and discharge polarization curves of three-electrode Zn-air batteries using the NPMC-1000, NPMC-1100, or commercial Pt/C catalyst as both of the air electrodes, along with the corresponding curve (that is, Pt/C + RuO2) for the three-electrode Zn-air battery with Pt/C and RuO2 nanoparticles as each of the air electrodes, respectively. (D) Discharge/charge cycling curves of a three-electrode Zn-air battery using NPMC-1000 as air electrodes (0.5 mg cm−2 for ORR and 1.5 mg cm−2 for OER) at a current density of 2 mA cm−2. [From J. Zhang, Z. Zhao, Z. Xia, L. Dai, A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions. Nat. Nanotechnol.10, 444–452 (2015). Reprinted with permission from the Nature Publishing Group.]

Mentions: Bifunctional catalysts, which have the ability to catalyze both ORR and OER in aqueous media, are highly desirable for rechargeable Zn-air batteries. Noble metal and nonprecious metal catalysts, such as metal oxides supported by carbon, have long been investigated in aqueous electrolytes as bifunctional catalysts to facilitate ORR and OER (163–165). In contrast, carbon-based metal-free bifunctional catalysts are a recent development (15, 30, 156, 166). Through polymerization of aniline in the presence of phytic acid to produce polyaniline (PANi) aerogels (167) and subsequent pyrolysis, we have recently produced 3D N and P co-doped mesoporous nanocarbon (NPMC) foams that have a surface area of up to ~1663 m2 g−1 and good electrocatalytic properties for both ORR and OER (30). When used as air electrodes for primary batteries, the NPMC-based Zn-air batteries showed an open circuit potential of 1.48 V, a specific capacity of 735 mAh gZn−1 (corresponding to an energy density of 835 Wh kgZn−1), and a peak power density of 55 mW cm−2, and could sustain stable operation for 240 hours after mechanical recharging (30). In addition, two-electrode rechargeable batteries based on the NPMC-1000 (pyrolysis temperature: 1000°C) air electrode could be stably cycled for 180 cycles at 2 mA cm−2 (Fig. 11A). Although NPMC-1000 accelerates both ORR and OER, a certain degree of irreversibility is unavoidable because of the different catalytic activities of the same catalyst toward ORR and OER reactions. Consequently, a deteriorating performance was observed for the two-electrode rechargeable Zn-air battery during a long-term cycling test. Therefore, to further improve the NPMC battery performance, we have also constructed a three-electrode rechargeable Zn-air battery (Fig. 11B), in which the NPMC bifunctional catalysts are prevented from being contacted with the oxidative (or reductive) potential during ORR (or OER), to study the electrocatalytic activities of the NPMC foam for both OER and ORR independently. In this case, the activities toward ORR and OER could be independently regulated by adjusting the catalyst mass loading on each of the two air electrodes, and a balanced reversible transfer between oxygen reduction and evolution was readily achieved. Figure 11C shows the discharge and charge polarization curves for the three-electrode batteries with various air electrodes. The three-electrode rechargeable Zn-air battery using NPMC-1000 as air electrodes showed no obvious voltage change over 600 discharge/charge cycles (for 100 hours, Fig. 11D), comparable to that of a three-electrode Zn-air battery using the state-of-the-art Pt/C and RuO2 as the ORR and OER catalysts, respectively (30). The Zn-air battery based on the NPMC air electrodes is comparable to, or even better than, most of the recently reported rechargeable Zn-air batteries based on metal/metal oxide electrodes (165, 168–170). To gain insights into the ORR and OER catalytic mechanisms of the NPMC metal-free bifunctional catalysts, we performed the first-principles calculations using the DFT methods to determine the electronic structures and catalytic reactions for the N, P co-doped carbon structures. Our calculations revealed that the N, P co-doping and the graphene edge effect are crucial for the bifunctional electrocatalytic activities of our NPMC materials (30).


Carbon-based electrocatalysts for advanced energy conversion and storage.

Zhang J, Xia Z, Dai L - Sci Adv (2015)

Performance of rechargeable Zn-air batteries.(A) Discharge/charge cycling curves of a two-electrode rechargeable Zn-air battery at a current density of 2 mA cm−2 using the NPMC-1000 (pyrolysis at 1000°C) air electrode. Three-electrode Zn-air batteries. (B) Schematic illustration for the basic configuration of a three-electrode Zn-air battery by coupling a Zn electrode with two air electrodes to separate ORR and OER. The enlarged parts illustrate the porous structures of the air electrodes, which facilitates the gas exchange. (C) Charge and discharge polarization curves of three-electrode Zn-air batteries using the NPMC-1000, NPMC-1100, or commercial Pt/C catalyst as both of the air electrodes, along with the corresponding curve (that is, Pt/C + RuO2) for the three-electrode Zn-air battery with Pt/C and RuO2 nanoparticles as each of the air electrodes, respectively. (D) Discharge/charge cycling curves of a three-electrode Zn-air battery using NPMC-1000 as air electrodes (0.5 mg cm−2 for ORR and 1.5 mg cm−2 for OER) at a current density of 2 mA cm−2. [From J. Zhang, Z. Zhao, Z. Xia, L. Dai, A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions. Nat. Nanotechnol.10, 444–452 (2015). Reprinted with permission from the Nature Publishing Group.]
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
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Figure 11: Performance of rechargeable Zn-air batteries.(A) Discharge/charge cycling curves of a two-electrode rechargeable Zn-air battery at a current density of 2 mA cm−2 using the NPMC-1000 (pyrolysis at 1000°C) air electrode. Three-electrode Zn-air batteries. (B) Schematic illustration for the basic configuration of a three-electrode Zn-air battery by coupling a Zn electrode with two air electrodes to separate ORR and OER. The enlarged parts illustrate the porous structures of the air electrodes, which facilitates the gas exchange. (C) Charge and discharge polarization curves of three-electrode Zn-air batteries using the NPMC-1000, NPMC-1100, or commercial Pt/C catalyst as both of the air electrodes, along with the corresponding curve (that is, Pt/C + RuO2) for the three-electrode Zn-air battery with Pt/C and RuO2 nanoparticles as each of the air electrodes, respectively. (D) Discharge/charge cycling curves of a three-electrode Zn-air battery using NPMC-1000 as air electrodes (0.5 mg cm−2 for ORR and 1.5 mg cm−2 for OER) at a current density of 2 mA cm−2. [From J. Zhang, Z. Zhao, Z. Xia, L. Dai, A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions. Nat. Nanotechnol.10, 444–452 (2015). Reprinted with permission from the Nature Publishing Group.]
Mentions: Bifunctional catalysts, which have the ability to catalyze both ORR and OER in aqueous media, are highly desirable for rechargeable Zn-air batteries. Noble metal and nonprecious metal catalysts, such as metal oxides supported by carbon, have long been investigated in aqueous electrolytes as bifunctional catalysts to facilitate ORR and OER (163–165). In contrast, carbon-based metal-free bifunctional catalysts are a recent development (15, 30, 156, 166). Through polymerization of aniline in the presence of phytic acid to produce polyaniline (PANi) aerogels (167) and subsequent pyrolysis, we have recently produced 3D N and P co-doped mesoporous nanocarbon (NPMC) foams that have a surface area of up to ~1663 m2 g−1 and good electrocatalytic properties for both ORR and OER (30). When used as air electrodes for primary batteries, the NPMC-based Zn-air batteries showed an open circuit potential of 1.48 V, a specific capacity of 735 mAh gZn−1 (corresponding to an energy density of 835 Wh kgZn−1), and a peak power density of 55 mW cm−2, and could sustain stable operation for 240 hours after mechanical recharging (30). In addition, two-electrode rechargeable batteries based on the NPMC-1000 (pyrolysis temperature: 1000°C) air electrode could be stably cycled for 180 cycles at 2 mA cm−2 (Fig. 11A). Although NPMC-1000 accelerates both ORR and OER, a certain degree of irreversibility is unavoidable because of the different catalytic activities of the same catalyst toward ORR and OER reactions. Consequently, a deteriorating performance was observed for the two-electrode rechargeable Zn-air battery during a long-term cycling test. Therefore, to further improve the NPMC battery performance, we have also constructed a three-electrode rechargeable Zn-air battery (Fig. 11B), in which the NPMC bifunctional catalysts are prevented from being contacted with the oxidative (or reductive) potential during ORR (or OER), to study the electrocatalytic activities of the NPMC foam for both OER and ORR independently. In this case, the activities toward ORR and OER could be independently regulated by adjusting the catalyst mass loading on each of the two air electrodes, and a balanced reversible transfer between oxygen reduction and evolution was readily achieved. Figure 11C shows the discharge and charge polarization curves for the three-electrode batteries with various air electrodes. The three-electrode rechargeable Zn-air battery using NPMC-1000 as air electrodes showed no obvious voltage change over 600 discharge/charge cycles (for 100 hours, Fig. 11D), comparable to that of a three-electrode Zn-air battery using the state-of-the-art Pt/C and RuO2 as the ORR and OER catalysts, respectively (30). The Zn-air battery based on the NPMC air electrodes is comparable to, or even better than, most of the recently reported rechargeable Zn-air batteries based on metal/metal oxide electrodes (165, 168–170). To gain insights into the ORR and OER catalytic mechanisms of the NPMC metal-free bifunctional catalysts, we performed the first-principles calculations using the DFT methods to determine the electronic structures and catalytic reactions for the N, P co-doped carbon structures. Our calculations revealed that the N, P co-doping and the graphene edge effect are crucial for the bifunctional electrocatalytic activities of our NPMC materials (30).

Bottom Line: Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries.Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries.We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance.

View Article: PubMed Central - PubMed

Affiliation: Center of Advanced Science and Engineering for Carbon (Case4Carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.

ABSTRACT
Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance.

No MeSH data available.


Related in: MedlinePlus