Facile Synthesis of Mayenite Electride Nanoparticles Encapsulated in Graphitic Shells Like Carbon Nano Onions: Non-noble-metal Electrocatalysts for Oxygen Reduction Reaction (ORR).

Karim Khan,Qudrat Ullah Khan,Sayed Ali Khan,Muhammad Aslam,Ayesha Khan Tareen,Zhengbiao Ouyang,Han Zhang,Yupeng Zhang,Renheng Wang,Zhongyi Guo,Muhammad Rauf

doi:10.3389/fchem.2019.00934

Abstract

This manuscript presented a large scale synthesis of Graphitic Shells like carbon nano onions (GS-CNOs) by direct solution method using mayenite electride as a catalyst for synthesis of CNOs. Thermal characterization, microstructural analysis, and high resolution electron microscopy have confirmed the graphitization and revealed the resulting GS-CNOs with particle size about 15 nm, maximum BET surface area of 214 m2.g−1, and moderate conductivity of 250 S.cm−1, thus providing a new approach to synthesize GS-CNOs. The reported GS-CNOs, which acts as more active but less expensive electrocatalysts with onset potential of 1.03 V, half wave potential of 0.88 V vs. the reversible hydrogen electrode (RHE), and limited current density of 5.9 mA.cm−2, higher than that of benchmark 20% Pt/C (1.02 eV, 0.82 V, 5.2 mA.cm−2). The synthesized nano-powder acts as an origin of ORR activity via a four electron (4e−) pathway, along with significantly enhanced stability, in alkaline media. The high ORR activity is ascribed to GS-CNOs embedded sufficient metallic C12A7:e− particles, which favor faster electron movement and better adsorption of oxygen molecules on catalyst surface. Hence, we explored first time large scale synthesis of GS-CNOs with gram level and provide efficient approach to prepare novel, lowest cost, potential non-noble metals catalyst for fuel cells.

Highlights

Technologies retrospect and the advancements in the already existing technology; usually come with the development of new materials (Tahir et al, 2015; Huang et al, 2016; Jiang et al, 2016; Khan et al, 2016, 2018a,b,c,d,e, 2019a,b,c, 2020; Wang et al, 2016; Zhang et al, 2016; Ren et al, 2017; Zou et al, 2017; Li et al, 2018; Mahmood et al, 2018)
In this paper we are more interested in synthesis and applications of Graphitic Shells like carbon nano onions (GS-CNOs) for electrocatalytic applications because of their higher BET specific surface area, durability and enhanced expected stability due to addition of the C12A7:e−
In section we will discuss in detail the characterizations about well spherical shaped nanosized GS-CNOs and most importantly we will concentrate on their applications for ORR in fuel cell

Summary

Introduction

Technologies retrospect and the advancements in the already existing technology; usually come with the development of new materials (Tahir et al, 2015; Huang et al, 2016; Jiang et al, 2016; Khan et al, 2016, 2018a,b,c,d,e, 2019a,b,c, 2020; Wang et al, 2016; Zhang et al, 2016; Ren et al, 2017; Zou et al, 2017; Li et al, 2018; Mahmood et al, 2018). The CNOs has desirable an electrical conductivity and surface area, higher than CNTs make them potential electrocatalytic ORR applicants for advancement of fuel cells (Xu et al, 2006).

Results

Conclusion