Chemical activation of carbon materials for supercapacitors: Elucidating the effect of spatial characteristics of the precursors

•Effect of redox conditions on the surface wettability of a sandstone was investigated using Atomic Force Microscopy (AFM).•AFM probes functionalised with both polar (NH2 and COOH) and non-polar (CH3) crude oil components were utilised.•Adhesion forces between probes and rock surfaces decreased in the reducing fluid: NH2 (∼70 %) >COOH (∼36 %) >CH3 (∼3 %).•Sandstone morphology was affected by the reducing fluid with dissolution of mineral composition in cemented pores observed.