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CuInS2 (CIS) thin films with petal-like nanostructures were synthesized in situ on copper substrates through a facile, one-step solvothermal method using InCl3 and thioacetamide ethylene glycol solution. In order to reveal the growth mechanism of CIS petal-like nanostructures, we synthesized CIS thin films with different morphologies at various reaction times. CIS thin films had a petal-like nanostructure. The petal possesses the preferentially exposed (222) facet, which becomes bigger and thicker as the increase of the reaction time. CIS petal-like nanostructures exhibited excellent light absorption properties. The average light absorption value of CIS synthesized at a reaction time of 4 h reached to 96.5%, and the minimum light absorption value even reached to 92% for that synthesized at a reaction time of 10 h. The CIS petal-like nanostructures synthesized at a reaction time of 4 h exhibit a band gap of 1.58 eV, which is much larger than that of the corresponding bulk material (1.04 eV). Furthermore, the band gap of CIS petal-like nanostructure decreases with increasing reaction time due to the increased "petal" thickness. All these results showed that the light absorption properties and band gap of CIS petal-like nanostructures can be adjusted by controlling the reaction time, which also indicated the application advantages of CIS petal-like nanostructures in photovoltaic and photocatalysis. [ABSTRACT FROM AUTHOR]

The morphology, stability and electronic properties of Pd and Au monolayers supported by MoS2 substrate have been investigated by using the first principles calculations based on periodic density functional theory (DFT). The results demonstrated that the most stable site is top of Mo top of S ( T S ) for the adsorption of Pd and Au monolayers on MoS2. We found that Pd/MoS2 with lower adsorption energy of − 0.54 eV is energetically more stable than Au/MoS2. Due to the emergence of impurities state in the bandgap of MoS2, Pd/MoS2 and Au/MoS2 display metallic character upon coating of metal monolayers. We demonstrated that the Pd monolayer strongly hybrids with underlying Mo and S around the Fermi level, which is achieved by the intermediate Pd–S–Mo hybridized chains. On the contrary, intensity of impurities states around the fermi level is much weaker for Au/MoS2, which can be explained by weak hybridizations between sp state of Au and 4 d state of nearest neighboring Mo. The calculated results demonstrated that work functions are markedly modulated to 4.99 and 6.23 eV after coating of Pd and Au monolayer, respectively, which can be qualitatively explained by the fact that Pd (as accepter) received charge from the MoS2 host, while Au donated charge to the host. These findings promise potential applications in the fields of nanoelectronics in future, such as it's helpful to choose suitable electrode materials for MoS2-based nanodevices. [ABSTRACT FROM AUTHOR]

First-principles calculations based on periodic density functional theory (DFT) have been used to investigate the geometries, electronic structures, magnetic properties and diffusion behaviors of different noble metal adatoms (Pd, Pt, Cu, Ag and Au) on MoS2 monolayers. The results demonstrate that these adatoms can chemically adsorb on MoS2 monolayers. The band gaps of MoS2 monolayers with a Pd or Pt atom adsorbed are reduced owing to impurity states that emerge simultaneously within the gap region of the pristine MoS2 monolayer. The unpaired electrons in MoS2 monolayers with a Cu, Ag or Au atom adsorbed are spin polarized, resulting in total magnetic moments of 1.0 μB per supercell, which is caused by the strong hybridization between the metal adatoms and surrounding Mo or S atoms. Long-range antiferromagnetic (AFM) coupling has been observed between group IB metal adatoms. Due to charge transfer between adatoms and the MoS2 host, the work functions were modulated upon adsorption of noble metals. In addition, the diffusion behaviors of noble metal adatoms on the MoS2 monolayer suggest that Cu, Pd and Pt atoms favor the formation of a metal nanotemplate on the MoS2 monolayer, and Ag and Au are likely to form isolated particles in the initial growth stage. These findings may provide useful guidance to extend the potential applications of MoS2 in low-dimensional nanoelectronic and spintronic devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] Silver nanosphere with good homogeneity and dispersity was synthetized. [•] The enhancement ratio was relative to the thickness of dye-doped silica layer. [•] The strongest fluorescence signal obtained as dye-SiO2 layer tuned to 10 nm. [•] An 11-fold enhancement was realized, compared with the sample without silver core. [ABSTRACT FROM AUTHOR]