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使用第一原理密度泛函理论中的离散变分方法(DFT-DVM)对(PM_12O_40)~(n-)-(M=Mo,W,V),(PMo_9W_3O_40)~(3-),(PMo_9V_3O_(40)~(-6)五种Keggin结构杂多阴离子进行了电子结构计算,讨论了骨架金属原子对Keggin结构杂多阴离子的电荷分布、成键作用、热稳定性、氧化还原性等的影响.结果表明,骨架金属原子对Keggin阴离子的电荷分布和成键作用均有一定的影响,以Mo,W,V作骨架金属原子的Keggin阴离子(PM_12O_40)~(n-)的热稳定性顺序为:(PW_12O_40)~(3-)>(PMo_(12)O_(40))~(3-)>(PV_(12)O_(40))~(15-).提出了判断杂多阴离子氧化性强弱的两因素法——脱出晶格氧的难易程度和LUMO轨道电负性,并根据两因素法得到氧化性强弱顺序为:(PV_(12)O_(40))~(15-)>(PMo_(12)O_(40))~(3-)>(PW_(12)O_(40))~(3-),同时,讨论了当(PMo_(12)O_(40))~(3-)中的Mo部分被W和V取代后,即(PMo_9W_3O_(40))~(3-),(PMo_9V_3O_(40))~(6-),其中取代原子对电子结构的影响,结果表明,W取代使整个阴离子的稳定性增强,但氧化性减弱,V取代,使稳定性减弱,但氧化性增强.
(PM_12O_40) ~ (n -) - (M = Mo, W, V), (PMo_9W_3O_40) ~ (3 -) and (PMo_9V_3O_4) were measured using the DFT-DVM method in the first- (40) ~ (-6) five Keggin structure heteropolyanion electronic structures were calculated to discuss the skeletal metal atom Keggin structure of heteropolyanion charge distribution, bonding, thermal stability, redox properties and so on The results show that the skeleton metal atoms have a certain influence on the charge distribution and bond formation of Keggin anion. The thermal stability of Keggin anion (PM_12O_40) ~ (n-) with Mo, W, V as the framework metal atom is (PV_ (12) O_ (40)) to (15), a method of judging the heteropolyanion oxidation property Strength of the two-factor method - the degree of prolapse of lattice oxygen and LUMO orbital electronegativity, and according to the two-factor method to obtain the order of the oxidative strength: (PV_ (12) O_ (40)) ~ (12) O_ (40)) ~ (3-) and (PMo_ (12) O_ (40)) ~ (3)> (PW_ (12) O_ (3-), (PMo_9W_3O_ (40)) ~ (3 -), (PMo_9V_3O_ (40)) ~ (6-) were replaced by W and V. The results showed that Show that W is taken On behalf of the stability of the anion increased, but weakened oxidation, V substitution, the stability weakened, but increased oxidation.