Porous NiOx nanostructures templated by polystyrene-block-poly(2-vinylpyridine) diblock copolymer micelles

Abstract

A facile synthetic route to NiO x nanostructures using various amphiphilic polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymers as templates was investigated. The synthesis targets NiO x nanostructures with a large surface area in order to allow an efficient functionalization, e.g., through loading with dyes to enable photo-induced hole injection for use in dye-sensitized solar cells or in (photo-) catalytic systems. The complete synthetic process to NiO x contains several steps: (i) the dissolution of the diblock copolymer, (ii) the subsequent addition of Ni 2+ , followed by the formation of core-corona micelles and eventually, (iii) further addition of Ni 2+ , resulting in the formation of a macroscopic precipitate. In all cases, (iv) deposition onto different substrates and calcination yielded NiO x films. All intermediates were thoroughly investigated using scanning or transmission electron microscopy, dynamic light scattering, and UV-vis spectroscopy. In contrast to the well-established synthetic route via the commercially available Pluronic F108 triblock copolymer, in our case a variety of different morphologies was found, i.e. spherical particles, toroid structures, or networks. Furthermore, the obtained BET area of about 50 m 2 g À1 is comparable to the value for conventionally obtained NiO x surfaces. First dye sensitization experiments with coumarine 343 confirm that the dye binds to the surface, which is a prerequisite for using the material as a photo-electrode. The presented route to porous NiO x is easy and provides superior control over the morphology of the intermediates involved in nanostructure formation.

Dye-sensitized PS- b -P2VP-templated nickel oxide films for photoelectrochemical applications

“…The synthetic procedure for the preparation of templated NiO films followed that described in the literature [38]. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) was synthesized via sequential anionic polymerization using a procedure adopted from the literature [66].…”

“…Porous nanostructured NiO films were deposited onto fluorine-doped tin oxide (FTO)-coated glass substrates according to a procedure previously described for deposition on glass substrates using amphiphilic polystyrene-block-poly-(2-vinylpyridine) (PS 75 -b-P2VP 25 ) diblock copolymers-the subscripts denote the weight fraction of the corresponding block [38]. The procedure was repeated three times to obtain three-layer films with homogeneous film thicknesses of 150-200 nm as measured by scanning electron microscopy (figure 1).…”

“…Efforts have targeted the preparation of nanostructured NiO films to increase the active surface area of the electrode, and thus to optimize the loading in photocatalytic units [32][33][34][35][36][37]. A facile synthetic route to nanostructured NiO films with a Brunauer-Emmett-Teller (BET) area of about 50 m 2 g 21 has been recently described based on the use of amphiphilic polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymers as templates [38]. We report here on the sensitization of such a material with an organic pushpull dye and demonstrate the potential of templated NiO film preparation for photoelectrochemical applications.…”

Controllable self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine)

“…Dye‐sensitized PS‐ b ‐P2VP/NiO nanocomposites were prepared by depositing PS‐ b ‐P2VP‐templated NiO films onto glass coated with fluorine‐doped tin oxide to study PEC applications. The NiO films are promising for the construction of dye‐sensitized photocathodes in PEC cells …”

“…The self‐assembly of polystyrene‐ block ‐poly(2‐vinylpyridine) (PS‐ b ‐P2VP) (Fig. (a)), a binary BCP, has been widely utilized in various applications such as templates for the synthesis of inorganic materials, high density information storage media, sensors, photo‐catalysis and photosensitive electrodes …”