Tin-assisted fully exposed Pt clusters are fabricated on the core–shell nanodiamond@graphene (ND@G) hybrid support (a-PtSn/ND@G). The obtained atomically dispersed Pt clusters, with an average Pt atom number of 3, were anchored over the ND@G support by the assistance of Sn atoms as a partition agent and through the Pt–C bond between Pt clusters and defect-rich graphene nanoshell. The atomically dispersed Pt clusters guaranteed a full metal availability to the reactants, a high thermal stability, and an optimized adsorption/desorption behavior. It inhibits the side reactions and enhances catalytic performance in direct dehydrogenation of n-butane at a low temperature of 450 °C, leading to >98% selectivity toward olefin products, and the turnover frequency (TOF) of a-PtSn/ND@G is ∼3.9 times higher than that of the traditional Pt3Sn alloy catalyst supported on Al2O3 (Pt3Sn/Al2O3).
In the present work, a novel Sn-assisted synthetic protocol is developed to control the growth and the optical performance of all-inorganic perovskite nanocrystals (NCs). We systematically elucidate the roles that the Sn4+ (i.e., SnBr4 and SnCl4) and Sn2+ (i.e., SnBr2, SnCl2 and Sn(OAc)2) species played in tuning the morphologies and optical properties of the resulting NCs in open air or under Ar atmosphere, respectively. Interestingly, the Sn4+ cations restrain the growth of the perovskite NCs along a specific plane and consequently lead to the generation of nanoplatelets (NPLs) with thicknesses of a few perovskite unit cell layers, exhibiting the quantum confinement effect. The co-existence of two populations of NCs with different thicknesses contributes to the formation of two well-defined optical absorption bands and photoluminescence (PL) emissions. The unusual disproportionation growth of the perovskite NCs was further confirmed by comparison of NCs grown in open air and under Ar atmosphere, respectively. Perovskite NCs fabricated under Ar atmosphere in the presence of either SnBr2 or SnCl2 showed a single PL emission. However, when the reactions were carried out in the open air, dual optical absorbance and PL emissions were observed. Moreover, by adjusting the input of Sn salts in the precursors, the band structure and PL properties can be precisely tuned. The present strategy can be extended to other tetravalent ions such as Ti4+. We finally employed freshly made dual-emissive CsPbBr3 perovskite NCs to fabricate a prototype white light-emitting diode (WLED) with a commercially available 365 nm GaN chip.
危险品化学品经营许可证（带存储）