Site-selective deposition of metal−organic frameworks (MOFs) on metal nanocrystals has remained challenging because of the difficult control of the nucleation and growth of MOFs. Herein we report on a facile wet-chemistry approach for the selective deposition of zeolitic imidazolate framework-8 (ZIF-8) on anisotropic Au nanobipyramids (NBPs) and nanorods. ZIF-8 is selectively deposited at the ends and waist and around the entire surface of the elongated Au nanocrystals. The NBPbased nanostructures with end-deposited ZIF-8 exhibit the best surfaceenhanced Raman scattering (SERS) performance, implying that molecules can be concentrated by ZIF-8 at the hot spots. In addition, the SERS signal exhibits good selectivity for small molecules because of the molecular sieving effect of ZIF-8. This study opens up a promising route for constructing plasmonic nanostructures with site selectively deposited ZIF-8, which hold enormous potential for molecular sensing, optical switching, and plasmonic catalysis.

The structural and electronic properties of [PW(12)O(40)](3-) (PW(12)) anion deposited on a graphene layer are investigated by using periodic density functional theory. The equilibrium geometries of graphene-PW(12) (G-PW(12)) are examined based on six different configurations. The adsorption energy and charge transfer between PW(12) and graphene are calculated and analyzed. We found that the interaction between PW(12) and graphene are noncovalent. The formation of G-PW(12) complex is theoretically predicted to be feasible from an energetic perspective with electron transfer from the PW(12) to graphene.

Water oxidation is a key half reaction in the energy conversion scheme. The reaction mechanism for the oxidation of H2O to O2 catalyzed by single-Ru-substituted polyoxometalates, [Ru(III)(H2O)XW11O39](n-) (X = Si(IV), Ge(IV)), was investigated by means of density functional calculations. The electronic structure of the pre-activation intermediates indicates that the aqua ligand is prone to accommodate the proton coupled electron transfer (PCET) process to achieve the active group [Ru(V)=Oa], and the high valent oxo-ruthenium(V) species are responsible for the O-O forming event. Three possible proton acceptors were designed for the rate-determining step (Ob, Oa, and H2O), the calculated results support that the bridge Ob atom of the polytungstate ligand will act as the most favorable proton acceptor in the O-O bond formation, with an energy barrier of 28.43 kcal mol(-1). A detailed information of the peroxidic intermediates in the oxidation process was also characterized, both the peroxo-species [Ru(IV)(OO)SiW11O39](6-) and [Ru(V)(OO)SiW11O39](5-) show the six-coordinate isomer with an open terminal geometry is more favorable than the close seven-coordinate ones. In addition, the replacement of the heteroatom in XO4(n-) can effectively tune the catalytic activity of polyoxometalates, in the order of Ge(IV) > Si(IV).

The novel dyes of organoimido-substituted hexamolybdates for positive type dye-sensitized solar cells (p-type DSSCs) have been studied on the basis of time-dependent density functional theory (TDDFT) calculations. The electronic absorption spectra, light harvesting efficiency (LHE), charge separation efficiency (CSE), and holes injecting efficiency (HJE) of designed systems have been systematically investigated. The results reveal that the long π-conjugated bridge and auxochrome play crucial roles in red-shifting the absorption bands and reinforcing the intensity of the bands. Based on [(n-C4H9)4N]2[Mo6O18(N-1-C10H6-2-CH3)], the designed systems 6 and 4 are good candidates for p-type DSSC dyes due to the strong absorption in the visible region as well as high LHE, CSE, and HJE. The maximum absorption of the one-electron-reduced system obviously red-shifts to the visible region. Therefore, the highly efficient dyes of p-type DSSC can be prepared by reducing POM-based organic–inorganic hybrids which have both long π-conjugated bridge and auxochrome.

A class of stable TMC (TM = Co, Ni, and Cu) monolayers with entirely planar pentacoordinate carbon in their ground states and their promising functional applications in spintronics, electronics, and mechanics are identified through the swarm-intelligence structure search method and first-principles calculations.