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Since the discovery of carbon nanotubes (CNTs) by Iijima in 1991, [1] extensive attention has been paid to hollow tubular nanostructures because of their particular significance and prospective applications in nanometer-scale devices, chemical and biological separations, catalysis, and biological sensors. [2][3][4][5][6] Furthermore, metal nanotubes, especially magnetic-metal nanotubes, have inspired particular interest due to their intriguing electronic, optical, and mechanical properties, magnetic characteristics, and catalytic properties. [7][8][9] To date, various methods, such as thermal decomposition of precursors, [10] hydrothermal synthesis, [11] spontaneous coalescence of nanoparticles, [12] galvanic displacement reactions, [13] and electrochemical deposition, [14] have been developed to prepare tubular nanostructures. However, there have been few reports on the fabrication of magnetic nanotubes, [15,16] and the preparation methods are limited, such as thermal decomposition of precursors and surface modification of pore walls. Among these methods, the template-mediated method, using porous anodic alumina (PAA) or polycarbonate (PC) membranes initiated by Martin and co-workers [17] has proven to be a versatile approach for the preparation of ordered arrays of nanomaterials because it provides many outstanding advantages that are superior to other approaches. The resulting uniform pore diameter and length can offer an easy way to produce intact nanostructures. Until now, despite their importance in nanotechnology, only a few examples [16,[18][19][20][21] of metal nanotube fabrication have been reported, such as nickel, [16] iron, [18] and cobalt, [18] in which the pore wall of the template was chemically modified before deposition. Our previous work [16] reported a preparation method for producing highly ordered arrays of Ni nanotubes, in which the pore wall of the alumina membrane was modified with an organoamine, methyl-c-diethylenetriaminopropyl dimethoxysilane. Because organoamines easily polymerize in a moist atmosphere, the entire fabrication process needs to be undertaken with care. A facile approach for fabricating perfectly aligned metal nanotube arrays is currently of intense interest. In this paper, we report a novel method to prepare a highly ordered array of magnetic Ni nanotubes by an electrodeposition method. The outstanding features of this method are its simplicity, convenience, and effectiveness. By adding a small amount of an amphiphilic triblock copolymer such as Pluronic P123 (EO 20 PO 70 EO 20 , EO: ethylene oxide, PO: propylene oxide, Aldrich) in an electrodeposition solution (see Experimental), highly ordered arrays of Ni nanotubes can be prepared by electrodeposition. Furthermore, by adjusting experimental parameters such as the current density and electrodeposition time, the wall thickness and length of Ni nanotubes can be effectively controlled. Figure 1a shows the transmission electron microscopy (TEM) image of a Ni nanotube after completely removing the alumina membrane with a...

Exploring high-efficiency and stable halide perovskite-based photocatalysts for the selective reduction of CO 2 to methane is a challenge because of the intrinsic photo-and chemical instability of halide perovskites. In this study, halide perovskites (Cs 3 Bi 2 Br 9 and Cs 2 AgBiBr 6 ) were grown in situ in mesoporous TiO 2 frameworks for an efficient CO 2 reduction. Benchmarked CH 4 production rates of 32.9 and 24.2 μmol g À 1 h À 1 with selectivities of 88.7 % and 84.2 %, were achieved, respectively, which are better than most reported halide perovskite photocatalysts. Focused ionbeam sliced-imaging techniques were used to directly image the hyperdispersed perovskite nanodots confined in mesopores with tunable sizes ranging from 3.8 to 9.9 nm. In situ X-ray photoelectronic spectroscopy and Kelvin probe force microscopy showed that the built-in electric field between the perovskite nanodots and mesoporous titania channels efficiently promoted photoinduced charge transfer. Density functional theory calculations indicate that the high methane selectivity was attributed to the Bi-adsorption-mediated hydrogenation of *CO to *HCO that dominates CO desorption.

Surface-modified titanium dioxides by highly dispersed NiO particles have an extended absorption in the visible light region and a reduced hole-electron pair recombination than unmodified TiO2. They have now been successfully applied as highly active heterogeneous photocatalysts in the visible light mediated direct cyclization of tertiary anilines with maleimides to give tetrahydroquinoline products in moderate to high yields at ambient temperature. In contrast with unmodified titanium dioxide catalysts that are conventionally used in a stoichiometric amount in combination with UVA light, only a catalytic amount (1 mol %) of the surface-modified TiO2 catalyst is needed along with visible light to efficiently catalyze the reaction. Compared with transition-metal complexes such as Ru(bpy)3Cl2 or Ir(ppy)2(dtbbpy)PF6, advantages of these surface-modified titanium dioxides as photocatalyst include high catalytic activity, low cost, ease of recovering, and being able to be used for at least nine times without significant decay of catalytic activity.

We for the first time report the synthesis of urchinlike BiPO 4 structure composed of nanorods and its photoluminescence properties. Scanning electron microscopy (SEM) images show urchinlike BiPO 4 structure composed of nanorods. The X-ray powder diffraction (XRD) pattern indicates that the crystal structure of the nanorod is monoclinic. The high-resolution transmission electron microscopy (HRTEM) image and Fast-Fourier-transform (FFT) pattern reveal the single-crystalline nature of the nanorod. The formation mechanism was proposed. BiPO 4 displays strong blue emission. Because of the similarities of the crystal structure and lattice constants and the suitable energy level with the rare-earth phosphate, BiPO 4 is a useful host for rare-earth ions. Ln 3+ is successfully doped in BiPO 4 and an efficient energy transfer from Bi 3+ to Ln 3+ takes place, which makes BiPO 4 :Ln (Ln ) Eu, Tb, Dy) emit strong luminescence in visible region. BiPO 4 :Ln will have promising application in high-performance luminescence devices, etc.