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The low concentration of formaldehyde (HCHO) released from decoration materials still display potential carcinogenicity due to the high toxicity of HCHO. Boron nitride nanotubes (BNNTs) as a stable material become a candidate for adsorbing HCHO. The differences in the structural stability of HCHO interacted with BNNTs with different diameters owing to the adsorption sites deserve further discussion. It provides a promising direction for the experimental preparation of appropriate diameter BNNTs. The structures, stability and electronic properties of HCHO adsorbed on the surfaces of BmNm (HCHOBmNm(s)), HCHO adsorbed at the ends of BmNm (HCHOBmNm(e)) and HCHO embedded into BmNm (HCHO@BmNm) (m = 48, 72 and 96) clusters have been investigated by using density functional theory. The results reveal that the diameter of B48N48 clusters (or (4,4) armchair single-walled BNNTs) is too small to embed HCHO while promote charge transfer between the HCHO and B48N48 clusters. The HCHOB48N48(s), HCHOB72N72(e) and HCHOB96N96(e) clusters exhibit higher chemical stability than other HCHOBmNm(s), HCHOBmNm(e) and HCHO@BmNm clusters. The results also suggest that BNNTs is an ideal material for HCHO adsorption since physisorption is helpful to recycle BNNTs. [ABSTRACT FROM AUTHOR]

The boron nitrides as the excellent sensors are used to detect certain harmful gases. The diameter of the boron nitrides is an important structural parameter to adjust the adsorption capacity. The structures, stabilities and electronic attributes of the NO2BmNm and NO2@BmNm (m = 48, 72 and 96) clusters have been investigated via first-principles. The bond angle ∠O–N–O = 134° of free NO2 molecules becomes slightly narrow (129.171°, 128.911° and 128.593°; 124.050°, 123.578° and 124.237°) of the NO2BmNm and NO2@BmNm clusters. The NO2 molecules prefer to embed in larger diameter BmNm (m = 72 and 96) clusters by the calculated binding energies per atom and HOMO–LUMO gaps. The charge amounts of the O2 fragments of the NO2BmNm clusters are almost the same while those of O2 fragments of the NO2@BmNm clusters obviously reduce. The internal charges of the O atoms of the NO2BmNm and NO2@BmNm (m = 48, 72 and 96) clusters transfer from the s to d orbitals. [ABSTRACT FROM AUTHOR]