Synergistic Effect of Nitrogen Doping and MWCNT Intercalation for the Graphene Hybrid Support for Pt Nanoparticles with Exemplary Oxygen Reduction Reaction Performance.

Kang Fu,Shenglin Yang,Ying Qian,Junhong Jin,Guang Li,Yang Wang,Linchang Mao

doi:10.3390/ma11040642

Abstract

The potential of graphene–multi-walled-carbon nanotube (G-M) hybrids prepared by the one-pot modified Hummers method followed by thermal annealing has been demonstrated by employing one as an electrocatalyst support for oxygen reduction reaction (ORR). N doping effectively modified the electronic structure of the G-M hybrid support, which was beneficial for the uniform distribution of Pt nanoparticles, and ORR activities were further improved. The newly prepared Pt/N-G-M catalyst demonstrated higher electrochemical activity than Pt/G-M and Pt/G catalysts. Even compared with commercial 20 wt % Pt/C (JM20), Pt/N-G-M delivered a better half-wave potential and mass activity. In terms of the durability test, Pt/N-G-M maintained 72.7% of its initial electrochemical active surface area (ECSA) after 2000 repeated potential cycles between 0 and 1.2 V in acidic media in relation to the 44.4% retention for JM20. Moreover, the half-wave potential for Pt/N-G-M showed only a minimal change, significantly superior to the 139 mV of loss for JM20. It is expected that Pt/N-G-M can be the potential candidate as a highly efficient and durable catalyst if utilized in proton exchange membrane fuel cells (PEMFCs).

Highlights

In the context of increasing worldwide energy demand and environmental pollution, fuel cells are an eye-catching arena owing to their exciting performance for power generation with low emission [1,2]
Successful preparation of graphene–multi-walled-carbon nanotube (G-M) and N-modification of the G-M (N-G-M) hybrid supports was confirmed by SEM, TEM, and XRD
In the synthesis of hybrid supports, the functionalization of multi-walled carbon nanotube (MWCNT) by strong oxidants to form various hydrophilic moieties accompanied by partial unzipping and peeling (Figure S1) enables its incorporation with graphene oxide (GO)

Summary

Introduction

In the context of increasing worldwide energy demand and environmental pollution, fuel cells are an eye-catching arena owing to their exciting performance for power generation with low emission [1,2]. Challenging issues including the high cost, insufficient oxygen reduction reaction (ORR) activity, and durability of the cathode catalysts are critical obstacles that hinder their practical commercial viability [4,5] Precious metals such as Pt or Pt-based alloys are routinely utilized as cathode catalysts due to their high catalytic performance towards ORR [6]. The effective and facile methods to prevent the restacking of graphene sheets are still underway It is well-recognized that introducing heteroatom N into the graphitic carbon structure contributes to tailoring the underlying catalyst–support interactions to boost the electrocatalytic activity and stability [27]. There have been extensive reports on nitrogen-doped graphene-supported catalysts, the results of which all demonstrate improved ORR activity and durability, or higher membrane electrode assembly (MEA) performance [28,29,30,31,32]. Pt nanoparticles were deposited on different supports via a facile ethylene glycol reduction technique, and the electrocatalytic performance was investigated and is discussed here in detail

Material Synthesis

Structural

Results and Discussion

Conclusions