Application feasibility of palladium-decorated reduced graphene oxide as a CH4 gas nano-sensor from the perspective of the van der Waals corrected DFT computations

Abstract

In this paper, ab initio simulation of structural, electronic and methane (CH 4 ) adsorption properties of palladium (Pd)-decorated reduced graphene oxide (rGO) has been performed using dispersion-corrected density functional theory. The stable adsorption geometry, adsorption energy, charge transfer, charge density difference, band structure, electronic density of states and work function are calculated to give further insight into the adsorption process. The stable rGO surface is composed of some local structural motifs from combinations of oxygen-containing functional groups (hydroxyl and epoxide groups). Our calculations indicate that, owing to the hybridization of palladium d-orbitals and oxygen p-orbitals, the Pd atom binds strongly to the epoxide group with the adsorption energies of −1.47 eV and −2.70 eV for the same side (GOOH(I)) and opposite sides (GOOH(II)) coadsorption of functional groups, respectively. Our results show that CH 4 molecules act as electron dopants for rGO and thus slightly change its conductivity. We also observe that, upon the introduction of Pd atoms, the CH 4 adsorption energies of GOOH(I) and GOOH(II) significantly modifies from −0.1 eV to −0.45 eV and −0.06 eV to −0.33 eV, respectively. Moreover, the charge transfer can be magnified from −0.01 e (−0.01 e) to −0.02 e (-0.03 e) by introducing Pd atoms into GOOH(I) (GOOH(II)) in the presence of CH 4 . Additionally, CH 4 adsorption changes the carrier mobility of Pd-decorated rGO. In light of these results, the Pd-decorated rGO can be a prominent candidate for CH 4 gas sensor application. • Using DFT calculations, adsorption of CH 4 on the Pd-decorated rGO is investigated. • CH 4 molecule is physisorbed on Pd-decorated rGO with reasonable adsorption energy. • Charge transfer is magnified by introducing Pd atom into rGO in the presence of CH 4 . • The direction of charge transfer is from the CH 4 molecule to the Pd-decorated rGO. • Carrier mobility and electron conductivity of Pd-decorated rGO changed after CH 4 adsorption.