Two-dimensional engineering of Pd nanosheets as advanced electrocatalysts toward formic acid oxidation Hamideh Saravani a,** , Majid Farsadrooh a , Mojtaba Share Mollashahi a , Maryam Hajnajafi b , Abdollatif Shafaei Douk a,* a Department of Chemistry, University of Sistan and Baluchestan, P. O. Box 98135-674, Zahedan, Iran b Department of Chemistry, Faculty of Sciences University of Guilan, P.O. Box 41335-1914 Rasht, Iran highlights graphical abstract  The one-step strategies are used to create the Pd nanosheets.  The catalytic activity and morphology of Pd nanosheets were affected by the presence of surfactant.  Pd nanosheets offer the excep- tional performance toward FAO. article info Article history: Received 23 March 2020 Received in revised form 22 April 2020 Accepted 8 May 2020 Available online xxx Keywords: Pd nanosheets Two-dimensional nanostructures Self-assembly Electrocatalyst Formic acid oxidation abstract 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 character- istics. 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, com- parison of both palladium nanosheets demonstrates that palladium nanosheets synthe- sized 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 * Corresponding author. ** Corresponding author. E-mail addresses: saravani@chem.usb.ac.ir (H. Saravani), shafaeidok7@gmail.com, shafaeidouk@pgs.usb.ac.ir (A.S. Douk). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (xxxx) xxx https://doi.org/10.1016/j.ijhydene.2020.05.072 0360-3199/© 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article as: Saravani H et al., Two-dimensional engineering of Pd nanosheets as advanced electrocatalysts toward formic acid oxidation, International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2020.05.072