Facile fabrication of N-doped graphene/Ti3C2Tx (Mxene) aerogel with excellent electrocatalytic activity toward oxygen reduction reaction in fuel cells and metal-air batteries

High cost, limited sources and poor durability hinder the wide use of noble metal based catalysts especially platinum (Pt) based materials for the oxygen reduction reaction (ORR). The design and fabrication of efficient non-platinum based electrocatalysts which are cost-effective and durable are pivotal steps to advances of energy conversion devices such as fuel cells and batteries. In this study, we prepared 3D porous N-doped graphene hybrid structure with two dimensional ultralight Ti3C2Tx (Mxene) nanosheets through hydrothermal method and freezdrying. The Mxene nanosheets not only perform as 2D conductive platform for charge transfer but provide large specific surface area for reactant species to interact with catalyst. The abundance of N rich catalytic sites, high degree of carbon graphitization and appropriate surface area make Mxene, N-doped graphene aerogel (Mxene/ NGA) as a favorable catalyst for ORR. It presents comparable catalytic activity (onset potential of 1.003 V vs RHE and current density (at 0.2 V vs RHE) of 5.65 mA cm(2)) with commercial 10% Pt/C (onset potential of 1.000 V vs RHE and current density (at 0.2 V) of 5.75 mA cm(2)). In addition, its durability over long operation time (40000s) is much better than that of Pt/. The Mxene/NGA also presents a noticeable Zn-air battery performance and its performance exceeds that of a 20 wt% Pt/C and IrO2 battery, rendering excellent chance for its utilization in green energy technologies.

Automated summary

The study successfully designed and prepared efficient, cost-effective, and durable non-platinum based electrocatalysts through the fabrication of a 3D porous N-doped graphene hybrid structure. These materials exhibited comparable catalytic activity to commercial platinum-based materials in the ORR, along with superior long-term stability.