title: A metal-free bifunctional electrocatalyst for oxygen reduction and oxygen evolution reactions.
abstract: The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are traditionally carried out with noble metals (such as Pt) and metal oxides (such as RuO₂ and MnO₂) as catalysts, respectively. However, these metal-based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. Here, we describe a mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area of ∼1,663 m(2) g(-1) and good electrocatalytic properties for both ORR and OER. This material was fabricated using a scalable, one-step process involving the pyrolysis of a polyaniline aerogel synthesized in the presence of phytic acid. We then tested the suitability of this N,P-doped carbon foam as an air electrode for primary and rechargeable Zn-air batteries. Primary batteries demonstrated 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)), a peak power density of 55 mW cm(-2), and stable operation for 240 h after mechanical recharging. Two-electrode rechargeable batteries could be cycled stably for 180 cycles at 2 mA cm(-2). We also examine the activity of our carbon foam for both OER and ORR independently, in a three-electrode configuration, and discuss ways in which the Zn-air battery can be further improved. Finally, our density functional theory calculations reveal that the N,P co-doping and graphene edge effects are essential for the bifunctional electrocatalytic activity of our material.
authors: Center of Advanced Science and Engineering for Carbon (Case4carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
authors: Jintao
authors: J
authors: Zhang
authors: Department of Materials Science and Engineering, Department of Chemistry, University of North Texas, Denton, Texas 76203, USA.
authors: Zhenghang
authors: Z
authors: Zhao
authors: Department of Materials Science and Engineering, Department of Chemistry, University of North Texas, Denton, Texas 76203, USA.
authors: Zhenhai
authors: Z
authors: Xia
authors: Center of Advanced Science and Engineering for Carbon (Case4carbon), Department of Macromolecular Science and Engineering, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
authors: Liming
authors: L
authors: Dai