Two-dimensional self-assembled nanostructures of palladium nanosheets are created during one-step strategies at room temperature. Palladium nanosheets are synthesized in the absence and presence of surfactant (CTAB) agent with the aim of considering the surfactant effect on the morphology and electrocatalytic activity of palladium nanosheets. In both reactions, carbon monoxide and acetic acid act as reducing agent and solvent, respectively. Both palladium nanosheets serve as two-dimensional advanced supportless electrocatalysts for oxidation of formic acid, and clarify higher mass activity and durability in comparison to the palladium anchored on carbon. The exceptional performance of both palladium nanosheets is ascribed to their self-support and huge surface area characteristics. Moreover, the paper well proves that the morphology and electrocatalytic efficiency of palladium nanosheets were seriously affected by the presence of surfactant. Palladium nanosheets synthesized in the absence and presence of surfactant display the flat and stack nanosheets with thicknesses of 3.48 and 4.22 nm, respectively. In addition, comparison of both palladium nanosheets demonstrates that palladium nanosheets synthesized in the absence of surfactant reflect better catalytic efficiency and durability. The presence and bonding of surfactant to the surface of palladium nanosheets lead to the occupancy of active sites and degradation of palladium nanosheets performance. We believe that these palladium nanosheets can be applied as advanced electrocatalysts for diverse applications, especially direct formic acid fuel cells. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.