In this study, we have investigated the size effects of palladium (Pd) doped single-vacancy defective graphene (SDG) surface to the adsorption of AsH3 and its dehydrogenated products on Pd using density functional theory calculations. Here, Pd cluster binding study revealed that Pd-6 nanocluster bound strongest to the SDG surface, while adsorption of As1-1, (x=0-3) on the most stable Pd-n, doped SDG showed that dehydrogenated arsine compounds adsorbed onto the surface stronger than the pristine AsH3 molecule. Charge analysis revealed that considerable amount of charge migration from Pd to dehydrogenated arsine molecules after adsorption may constitute strong adsorption for dehydrogenated arsine. In addition, study of thermodynamic pathways of AsH3 dehydrogenation on Pd,, doped SDG adsorbents indicated that Pd cluster doping on SDG adsorbent tends to be thermodynamically favorable for AsH3 decomposition than the single-Pd atom doped SDG. Hence, our study has indicated that Pd-6 clusters doped SDG is more advantageous as adsorbent material for AsH3 removal. (C) 2016 Elsevier B.V. All rights reserved.