The geometric stabilities, electronic structures and catalytic properties of tetrahedral Pt4 clusters anchored on graphene substrates are investigated using the first-principles methods. It is found that the small Pt4 clusters adsorbed on pristine graphene substrates easily interconvert between structural isomers by the small energy barriers, while the structural interconversion of Pt4 clusters on the defective graphene and oxygen-doped graphene (O-graphene) have the large energy barriers. Compared to other graphene substrates, the Pt4 clusters supported on the O-graphene substrate (Pt4/O-graphene) have the least geometrical distortion and the high symmetry of the Pt4 cluster can enhance the sensitivity of reactive gases. Moreover, the sequential reactions of CO oxidation on Pt4/O-graphene are investigated for comparison. Compared with the coadsorption reaction of CO and O2 molecules, the dissociative adsorption of O2 as a starting step has a small energy barrier (0.07 eV) and is followed through the Eley–Rideal reaction with an energy barrier of 0.42 eV (CO + Oads → CO2). The results provide valuable guidance for fabricating graphene-based catalysts as anode materials, and explore the microscopic mechanism of the CO oxidation reaction on atomic-scale catalysts.

•The atomic S atom is strongly bound on the Pt-graphene surfaces than that of the SH and H2S.•The adsorbed S, SH and H2S can regulate electronic and magnetic properties of Pt-graphene systems.•The dissociation of H2S or H2 with the preadsorbed SH has relatively large energy barriers.•The deposited S atom with the presence of H atoms can be converted into the SH and H2S.The adsorption and dissociation reactions of hydrogen sulfide (H2S) on the Pt atom anchored graphene (Pt-graphene) surfaces were investigated by first-principles calculations. It is found that the atomic S has stronger interaction with the Pt atom, while the SH and H2S species are weakly bound on the Pt-graphene surfaces. The adsorption of S-based species can regulate the electronic structure and magnetic properties of Pt-graphene systems. Besides, the calculated results show that the formation of SH and H from the H2S (H2S → SH + H) is rather easy and further the hydrogenation reaction generates the hydrogen molecular (H2), as well as leaving the SH anchors on the Pt atom (SH + H + H → SH + H2). Moreover, the preadsorbed S atom with the presence of H atoms can be converted into other species (SH or H2S) and thus inhibit the sulfur deposition on the Pt-graphene surfaces, which is expected to prevent the sulfur poisoning on graphene-based anode materials and boost the efficiency of fuel cells.

The atomic structures of indium (In) on silicon (Si) (1 0 0)-(2 × 1) surface are investigated by the local density approximation using first-principles pseudopotentials. Total energy optimizations show that the energetically favored structure is the parallel ad-dimer model. The adsorption energy of In on ideal Si(1 0 0)-(1 × 1) surface is significantly higher than that on reconstructed Si(1 0 0)-(2 × 1) surface, suggesting that In adsorption does not break the Si–Si dimer bond of the substrate. When Si surface contains single dimer vacancy defects, In chain will be interrupted, leading to disconnected In nanowires. Displacive adsorption of In on Si(1 0 0) is also considered, and the calculation suggests that interdiffusion of In into Si substrate will not be favorable under equilibrium conditions.

The geometric stabilities, electronic structures and catalytic properties of tetrahedral Pt4 clusters anchored on graphene substrates are investigated using the first-principles methods. It is found that the small Pt4 clusters adsorbed on pristine graphene substrates easily interconvert between structural isomers by the small energy barriers, while the structural interconversion of Pt4 clusters on the defective graphene and oxygen-doped graphene (O-graphene) have the large energy barriers. Compared to other graphene substrates, the Pt4 clusters supported on the O-graphene substrate (Pt4/O-graphene) have the least geometrical distortion and the high symmetry of the Pt4 cluster can enhance the sensitivity of reactive gases. Moreover, the sequential reactions of CO oxidation on Pt4/O-graphene are investigated for comparison. Compared with the coadsorption reaction of CO and O2 molecules, the dissociative adsorption of O2 as a starting step has a small energy barrier (0.07 eV) and is followed through the Eley–Rideal reaction with an energy barrier of 0.42 eV (CO + Oads → CO2). The results provide valuable guidance for fabricating graphene-based catalysts as anode materials, and explore the microscopic mechanism of the CO oxidation reaction on atomic-scale catalysts.