The disclosed technology generally relates to preparing two-dimensional material layers, and more particularly to releasing a graphene layer from a template substrate. According to an aspect, a method of releasing a graphene layer includes providing a template substrate on which the graphene layer is provided, the method comprising: subjecting the graphene layer and the template substrate to a water treatment by soaking the graphene layer and the template substrate in water such that water is intercalated between the template substrate and the graphene layer; and subjecting the graphene layer and the template substrate to a delamination process, thereby releasing the graphene layer from the template substrate.