First-principles Investigation On Electronic Properties And Surface Reactions Of NaTaO₃ Adsorbed With Single-metal Atoms

Energy scarcity and environmental pollution have long been the thorny issues facing the world.The study shows that the semiconductor photocatalytic decomposition of water and the photocatalytic reduction of CO₂ can effectively solve the above problems.Because the process uses solar energy,where the photocatalytic decomposition of water produces hydrogen in a clean way and does not cause harm to the environment.Photocatalytic reduction of CO₂ can not only effectively reduce the emission of CO₂ in the atmosphere,but also convert CO₂ and H₂O in the atmosphere into hydrocarbon energy we need for our production and life.There are many methods to improve photocatalytic efficiency,including carrying cocatalysts,doping with metal or non-metallic elements,constructing semiconductor heterostructures and so on.In this work,we selected the cocatalysts to improve the reaction activity since they can act as the reaction sites and promote the separation of photogenerated carriers.We have performed detailed density functional theory calculations on the effect of adsorbing single metal atoms（M=Fe,Co,Ni,Cu,Ru,Rh,Pd,Ag,Ir,Pt and Au）on the surface structure,electronic structure,work function,charge transfer and photocatalytic reaction mechanism of NaTaO₃（001）surface.Our results reveal that the adsorption of metal atoms on Na O-terminated surface is more stable than that on Ta O₂-terminated surface.The formation of multiple new bonds and the surface reconstruction are in favor of stabilizing the studied systems.The impurity states in the forbidden gap mostly originate from the hybridized nd orbitals of the adsorbed metal atoms and Ta atoms.The adsorption energies of the metal atoms are related to the bond lengths of metal-oxygen bonds and the amounts of interfacial charge transfer.It is found that a decrease in the work function of the surface is fairly proportional to the charge gained from the metal adatom,which indicates that the work function of NaTaO₃ can be regulated by the type of the metal adatom.Loading 3d metal atoms on the surface has better performance than 4d and 5d metal atoms in enhancing the activity of hydrogen evolution reaction.The performance of Co as the oxidation cocatalyst is better than other metals since its adsorption on the surface decreases the overpotential of oxygen evolution reaction by more than 1.1 V.The adsorption of single metal atoms on NaTaO₃ surface is favorable to the activation of CO₂ due to the elongated C=O bonds and the bent configuration of CO₂ molecule.The results of the present study can be employed in synthesizing optimal photocatalysts.