He Geping,Wang Di,HuangFu Huijun,Zhang Cunshe,Zhang Ben,Mi Yuanmei,Zheng Donghao
ZnWO 4 nanomaterials are gaining attention as a kind of multifunctional material in the field of electrochemical energy storage and photocatalysis. However, the controllable adjustment of their nanomorphology and bandgap width limit their wide application. So the nanostructured bifunctional Zn 1− x Ce x WO 4 ( x = 0.020, 0.022, 0.030) with tunable nanomorphology and bandgap width were prepared by a simple one-step hydrothermal method in this work. On the one hand, the microscopic morphology of the Zn 1− x Ce x WO 4 was changed from clusters to nanosheets with the addition of Ce 4+ . On the other hand, the doping of Ce 4+ generated oxygen vacancies and formed defect states in the ZnWO 4 semiconductor, reducing the energy bandgap width. Zn 1− x Ce x WO 4 ( x = 0.022) with the optimal doping ratio (nCe/(nCe + nZn) = 0.022) obtained a specific capacitance of 267.091 F g −1 at a current density of 1 A g −1 and an electrolyte of 6 M KOH, which is 3.7 times as great as the specific capacitance of ZnWO 4 (70.545 F g −1 ). In addition, the catalytic efficiency of Zn 1− x Ce x WO 4 ( x = 0.022) for Rhodamine B (RhB) reached 99.541% in 4.5 h. The doping of Ce 4+ can achieve the dual modulation of the morphology and bandgap width of ZnWO 4 , thus enhancing the electrochemical performance and photocatalytic degradation performance of ZnWO 4 . Graphical abstract
A series of Ce 1- x Cd x O mixed oxide catalysts prepared by co-precipitation method were tested for synthesis of glycerol carbonate (GC) from glycerol and diethyl carbonate (DEC). The microstructural and physicochemical properties of the bimetal catalysts were characterized by XRD, SEM, TEM, XPS, CO 2 -TPD, N 2 -adsorption, TG-DSC and 1 H NMR. The results show that the spherical particles of CdO were uniformly dispersed on the surface of lamellar CeO 2 . Besides, a noticeable increase was observed in the moderate basic sites concentration, because more oxygen atoms were adsorbed on the bimetal sample surface which was attributed to Ce 4+ doped into CdO lattice. The Ce 0.7 Cd 0.3 O sample annealed at 500 °C was observed with the highest catalytic activity. 96.84% of glycerol conversion and 100% selectivity to GC were obtained over this catalyst under the optimized conditions (5 wt.% catalyst of glycerol, 90 °C, 180 min, glycerol/DEC molar ratio of 1:3). Besides, it was found that the conversion of glycerol carbonate was synergistically accelerated by the moderate and strong basic sites.
The hexagonal perovskite oxide Ba7Nb4MoO20 is widely studied in chemical devices due to its oxide-ionic conductivity at high temperatures. Ce4+ doping into Ba7Nb4MoO20 was undertaken to optimize small polariton conduction and oxide ionic conductivity simultaneously. Ba7Nb4−xCexMoO20 materials were synthesized via solid phase sintering. XRD patterns indicate a single phase, SEM scans reveal increased densification with higher Ce doping concentrations, and the resistance temperature range expands from 400–900 °C to 300–1100 °C. Hall tests confirm that Ba7Nb4−xCexMoO20 carriers are electrons, indicating n-type conductivity. Nyquist plots illustrate that grain boundary resistance governs complex impedance, which shows gradual oxide ionic conductivity enhancement with rising temperature. The aging drift rate decreases to about 1%, suggesting good stability of Ba7Nb4−xCexMoO20 ceramics. These findings propose a feasible doping strategy for enhancing hexagonal perovskite oxide ceramics.
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