Modified bubbling transfer method for graphene delamination

Abstract

In the BB transfer, or so called electrochemical delamination process, a transfer film is firstly spray-coated on a stack formed by two graphene sandwiching a metal (Cu or Cr) foil as a protection layer. Then, direct current (dc) voltage is applied to the first stack as a cathode and an anode (from be a platinum wire, a carbon rod, or others) in an electrolyte aqueous solution. With application of the electrolysis potential, hydrogen bubbles appear at the graphene / metal foil interfaces, while oxygen bubble appear at the anode due to the reduction of water. These H2 bubbles provide a gentle but persistent force to detach the graphene film from the copper foil at its edges, and the process is aided by the permeation of the electrolyte solution into the interlayers as the edges delaminate.

Description

FIELD OF THE INVENTION[0001]The present invention relates to graphene delamination, and in particular to a modified bubbling transfer method for graphene delamination.BACKGROUND OF THE INVENTION[0002]Chemical vapor deposition (CVD) method for graphene growing provides a way for graphene industrial applications because it produces large area, flexibility, high transparency, and high electrical conductivity graphene film (referring to Li XS et al. Science; US patent: US20110091647). However, the traditional transfer method of delaminating graphene from a metal substrates usually includes using polymethylmacralate (PMMA) as a carrier material and a chemical etching step to remove the metal substrate (Li XS, et al. Nano Letters) . The PMMA film as carrier material is fragile and expensive. It is replaced with other transfer used polymer film, which could be selected from a group of materials including nitrocellulose lacquer, polyurethane, epoxy, and other ketone removable polymer coatin...

AI Technical Summary

Benefits of technology

The present invention is a modified bubbling transfer method that uses transfer cloth to drive the cathode and anode as close as they could without causing short circuit, which increases delamination speed and reduces non-uniformity caused by the bubbling process. This method has several advantages such as fastened reaction speed, high reaction efficiency, and quality preferred over prior art methods. The transferred graphene film keeps its flexibility, high transparency, and high electrical conductivity.

Problems solved by technology

The PMMA film as carrier material is fragile and expensive.

The etching step not only increases the production cost but also causes a lot of waste and extends the transfer time consumed.

Advantages of this technique are industrial scalability of the process and reusability of the Cu foil in multiple growth and delamination cycles.

However, the prior art method has some disadvantages: (1) Delaminating speed greatly decreases with increment of delamination areas.

(2) Control of the generating speed and the break force for each bubble is not easy, but they are very important for final graphene quality.

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