**5.2 Dry chemical methods**

The dry chemical methods are based on the same principle as the wet ones, but with the difference that these ones are performed under dry conditions. Several methodologies have been proposed as well, such as Yang *et al*. reported an electrochemical procedure for the etching of the Cu substrate to reduce the contamination in graphene [59]. Martins´ group developed a transference methodology *via* lamination into flexible substrates, using a direct transfer procedure without intermediates [60].
