The modulation of crystal surface is one of the important means of photocatalyst modification. BiOBr photocatalyst with exposed (1 1 0) facets was synthesized at room temperature and pressure using CaCO 3 as a directing agent in this experiment. The addition of CaCO 3 not only promoted the exposed facets of BiOBr from (1 0 2) to (1 1 0), but also improved its ability of photocatalytic degradation of pollutants, meanwhile, changed the specific surface area of BiOBr, provided more active sites, and enhanced the adsorption capacity of BiOBr. At the same time, the effects of different alkaline earth metals on the performance of BiOBr photocatalytic materials were compared, it was determined that the degradation rate of RhB of BiOBr photocatalyst reached 97% within 60 min when adding 500 wt% CaCO 3 , and the main active group in the degradation experiment was h + . In conclusion, BiOBr with different main exposed facets was prepared in this paper, and a new idea was provided for alkaline earth metals in the field of photocatalysis.
Songlin Li,Chen Wang,Zhaohui Lei,Shanfu Sun,Jie Gao,Pengfei Cheng,Hai Wang
A deep understanding of the relationship between the properties and structure of transition metal oxide semiconductor gas sensors is essential for optimizing sensor design. Comparing and analyzing the sensing properties of nanomaterials with different morphologies and crystal facets by combining the experiment analysis and the density functional theory (DFT) calculations could identify and understand the corresponding mechanisms at the atomic or ionic level. Here, grown Co 3 O 4 nanosheet (Co 3 O 4 -NS) with exposed (1 1 1) facets, and Co 3 O 4 nanorods (Co 3 O 4 -NR) with exposed (1 1 0) facets on alumina ceramic tubes were prepared and studied in sensing ethanol. The adsorption characteristics of ethanol on the sensor surface were analyzed by DFT calculation. The results demonstrated that the sensing performance of Co 3 O 4 -NR was superior to Co 3 O 4 -NS. The adsorption of hydroxyl groups in ethanol was better than the methyl groups on the surface. The oxygen and hydrogen atoms from the hydroxyl groups in ethanol had the lowest adsorption energies (E ads = −3.44 eV) when they interact with the Co atom and the indirectly adjacent low-coordinate oxygen atoms on the (1 1 0) surface, respectively. The synergistic adsorption of target gases by exposed surface atoms induced superior sensing properties of the material.
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