3D-porous electrocatalytic foam based on Pt@N-doped graphene for high performance and durable polymer electrolyte membrane fuel cells

Abstract

A new class of sustainable electrocatalysts based on Pt@N-doped graphene foam is developed for the oxygen reduction reaction of PEMFCs.

Nitrogen Functionalization of CVD Grown Three-Dimensional Graphene Foam for Hydrogen Evolution Reactions in Alkaline Media

“…The urea solution was stirred for 5 min, while ammonia was dropped until the pH reached 10. Subsequently, 2 mL of hydrated hydrazine was added as reducing agent, and afterwards the solution was introduced into the autoclave [ 14 ]. In order to prevent the graphene foam from breaking, a special Teflon support was designed for its slow diving and supporting during the hydrothermal process.…”

“…Incorporating nitrogen atoms into the graphene structure is considered a route to creating a valance band and, consequently, to change its electronic structure [ 13 ]. Thus, it is possible to tune the electrochemical properties of nitrogen-doped graphene to synthetize a stable and highly efficient non-metallic catalyst for oxygen reduction (ORR) [ 14 ], hydrogen production (HER) [ 15 , 16 ], and oxygen production (OER) reactions [ 17 ]. Li et al [ 15 ] indicated that the free-standing N-enriched carbon foam@WS 2 nanoflakes prepared by a thermal evaporation process, can be used as the working electrodes for HER in water splitting.…”

“…Nitrogen graphene functionalization can be carried out in situ by assisted chemical vapor deposition (CVD) using different nitrogen sources (e.g., ammonia, pyridine, poly-pyrrole, and acetonitrile) [ 18 ], and ex situ using thermal annealing [ 19 ], pyrolysis [ 20 ], arc-discharge [ 21 ], hydrothermal [ 14 , 22 , 23 , 24 ] and solvothermal [ 25 ] methods, plasma [ 26 ] and microwave [ 27 , 28 ] treatment, wet chemical synthesis [ 29 , 30 ], and lyophilization-assisted heat treatment [ 31 ]. Deng et al [ 25 ] performed the synthesis of N-doped graphene by the solvothermal method.…”

Recent developments of nanocarbon based supports for PEMFCs electrocatalysts

“…Therefore, there are different opinions about which N types are determinative for ORR activity. It is generally believed that pyridinic N and pyrrolic N are the main factors that improve the ORR electrocatalytic activity, forming a strong interaction with metal nanoparticles, while graphitic N has a positive effect on the improvement of the catalyst conductivity, and quaternary N can promote the adsorption and dissociation of O2 [95,96,99,100]. In contrast, different perspectives are inevitable, Zhao et al [101] and Hattig et al [102] hold the opinion that pyridinic N was the key to enhancing ORR activity.…”

N-doped graphene foam obtained by microwave-assisted exfoliation of graphite

“…Well-known methods of synthesis produce three-dimensional graphene materials effectively, but they are too expensive and require specialized equipment. The assembly of graphene flakes 25 , 26 by the hydrothermal method 27 is also popular, although not without disadvantages; self-organization of graphene sheets is the most common problem that researchers want to eliminate 28 . The microwave method 29 , 30 supports the synthesis of graphene, combining many advantages: it is fast, simple, does not require specialized equipment, and the starting material for foam production can be expanded graphite 31 or sucrose 32 .…”