Factors determining surface oxygen vacancy formation energy in ternary spinel structure oxides with zinc

Abstract

Spinel oxides are an important class of materials for heterogeneous catalysis including photocatalysis and electrocatalysis. The surface O vacancy formation energy (EOvac) is a critical quantity on catalyst performance because...

Trends in Surface Oxygen Formation Energy in Perovskite Oxides

“…A negative correlation is found, which is consistent with d 0 and d 10 binary oxide systems 23 as well as the (100) and (110) surfaces of Zn-containing normal spinels. 25 E Ovac from the B-cation layer of ScCoO 3 (62) appears to be an extreme layer for the BG plot ( Figure 3 b) but is not in the E form plot ( Figure 4 b). The high E Ovac in titanates comes from the electronic structure; all titanates have BG values exceeding 1.5 eV, and all nontitanates except for ScCoO 3 have BG values below 1.5 eV ( Figure 4 ).…”

“…This trend was also found in binary carbide, nitride, 24 and d 0 and d 10 binary oxide systems, 23 but not in zinc-containing normal spinels. 25 On the other hand, Figure 4 shows plots of E form versus minimum E Ovac . A negative correlation is found, which is consistent with d 0 and d 10 binary oxide systems 23 as well as the (100) and (110) surfaces of Zn-containing normal spinels.…”

“…While there have been extensive computational studies of O vacancy formation energies in the bulk, ,,, studies of surface E Ovac are quite limited have been increasing recently. ,− The band gap, bulk formation energy, and electron affinity were reported to correlate well with E Ovac in d 0 and d 10 binary oxides. Removal of neutral O results in two electrons being left behind.…”

Design of need-based phosphors and scintillators by compositional modulation in the ZnGa2−xAlxO4:Cr3+ spinel: pure compound versus solid solutions

“…The unit cell volume/lattice constant of ZnAl 2 O 4 is smaller than that of ZnGa 2 O 4 with their solid solutions having intermediate values depending on the composition. The oxygen formation energies are reported to be higher in ZnAl 2 O 4 than ZnGa 2 O 4 , 30 implying that oxygen vacancies are relatively easier to be formed in ZnGa 2 O 4 compared to ZnAl 2 O 4 . Thus, the changes in the lattice dimensions as well as oxygen vacancy formation energies explain the higher positron lifetimes in ZnGa 2 O 4 than ZnAl 2 O 4 .…”

Understanding and controlling the formation of surface anion vacancies for catalytic applications

“…With this background in mind, we calculated the E Ovac values and electronic structures for the (100), (110), and (111) surfaces of ZnAl 2 O 4 , ZnGa 2 O 4 , ZnIn 2 O 4 , ZnV 2 O 4 , ZnCr 2 O 4 , ZnMn 2 O 4 , ZnFe 2 O 4 , and ZnCo 2 O 4 , which are normal zinc-based spinel oxides, as shown in Fig. 5; 55 the (100) surface was found to be most stable in each case. With the exception of ZnCo 2 O 4 , the smallest E Ovac was found to be largest on the (100) surface, and the values for the (100) and (110) surfaces were found to correlate well with the E form value for each spinel.…”