Theoretical investigation of the effect of phosphate doping on the aggregation of Au atoms on an Al2O3 (0001) surface

Extent of Spin Contamination Errors in DFT/Plane-wave Calculation of Surfaces: A Case of Au Atom Aggregation on a MgO Surface

“…The highest occupied molecular orbital (HOMO) is a bonding orbital, and the lowest unoccupied molecular orbital (LUMO) is an anti-bonding orbital. The frontier orbitals do not change when Au 2 is adsorbed onto metal oxides such as MgO [35,43], Al 2 O 3 [18,57], and TiO 2 [58,59,60,61]. Hence, the HOMO and LUMO of Au 2 can be described by using the 6s orbital of 1 Au (φ1) and 6s orbital of 2 Au (φ2):φHOMO=normalA(φ1+φ2) φLUMO=normalB(φ1−φ2)…”

“…The d ( 1 Au-MgO) values of HS are also longer than those of the other states because of the insignificant interaction between the Au atoms of HS. When a Au cluster is adsorbed onto metal oxides, it acquires a slight positive charge and interacts with an O 2− ion electrostatically [16,17,18,35,43,44,58,59,60,61,64,65,66,67]. Furthermore, the charge on the Au cluster consisting of two or more Au atoms is polarized, and the Au atoms closer to the surface are more positively charged [17,44,60,65,67].…”

“…For instance, dissociation of hydrogen on metal surfaces is an elementary reaction for hydrogenation by heterogeneous metal catalysts, and dimerization of nitrogen atoms and nitric monoxide (NO) molecules are regarded as elemental reactions for NO x elimination from exhaust gases. In addition, both dissociation and dimerization of metal clusters on their support surfaces are crucial for clarifying the degradation mechanism of nanosized metal catalysts, especially gold catalysts [10,13,14,15,16,17,18].…”

“…The Au/MgO system is a typical gold catalyst system [14,16,35,42,43,44], and reaction (1) is related to the sintering of Au clusters on the MgO surface, which pertains to a crucial degradation of the gold catalyst [13,14,15,16,17,18], and its suppression. The potential energy curves of the closed singlet (LS: low spin), triplet (HS: high spin), and open singlet (BS: broken symmetry, which is a common name of open-shell structures estimated by spin-polarized calculations) states were estimated, and the spin contamination error in the open singlet state was estimated by the AP scheme (AP: BS state with AP correction).…”

Tuning Thermal Catalytic Enhancement in Doped MnO2–Au Nano-Heterojunctions

“…In nanocatalysis, in addition to the metal NPs, semiconductors can be used as supports in order to avoid NP aggregation, facilitate catalyst recovery, provide additional catalytic sites due to metal–support interactions, and facilitate the interaction or activation of substrates or intermediates. − However, to our knowledge, few works mentioned the metal–semiconductor heterojunction interactions towards thermal catalysis. Similar to photocatalysis, it has been established in thermal catalysis that semiconductors can contribute to prolong the lifetimes of thermally excited carriers, and potentially boost their catalytic properties …”