The present disclosure provides a reference electrode for providing a reference potential during measurement of a property of a sample. The reference electrode comprising: a reference electrode layer; and a reference layer provided over at least a part of the reference electrode layer and defining a sample receiving region which is separated from the reference electrode layer by the reference layer. In one embodiment, the reference layer comprises fluorinated or silanized graphene and/or fluorinated or silanized graphene oxide. Alternatively, the graphene or graphene oxide are functionalised or doped so as to form a super-hydrophobic reference layer.