Carbon dioxide electroreduction provides a useful source of carbon monoxide, but comparatively few catalysts could be sustained at current densities of industry level. Herein, we construct a high-yield, flexible and self-supported single-atom nickel-decorated porous carbon membrane catalyst. This membrane possesses interconnected nanofibers and hierarchical pores, affording abundant effective nickel single atoms that participate in carbon dioxide reduction. Moreover, the excellent mechanical strength and well-distributed nickel atoms of this membrane combines gas-diffusion and catalyst layers into one architecture. This integrated membrane could be directly used as a gas diffusion electrode to establish an extremely stable three-phase interface for high-performance carbon dioxide electroreduction, producing carbon monoxide with a 308.4 mA cm−2 partial current density and 88% Faradaic efficiency for up to 120 h. We hope this work will provide guidance for the design and application of carbon dioxide electro-catalysts at the potential industrial scale.

Developing noble metal-free water oxidation catalysts is essential for many energy conversion/storage processes (e.g., water splitting). Herein, we report the facile synthesis of hollow Co3O4 microspheres composed of porous, ultrathin (<5 nm), single-crystal-like nanosheets via a novel "self-template" route. The successful preparation of these hollow Co3O4 nanomaterials includes three main steps: (1) the synthesis of solid cobalt alkoxide microspheres, (2) their subsequent self-template conversion into hollow cobalt hydroxide microspheres composed of ultrathin nanosheets, and finally (3) thermal treatment of hollow cobalt hydroxide microspheres into the hollow Co3O4 material. The as-obtained hollow Co3O4 nanomaterial possesses a high BET surface area (∼180 m(2) g(-1)), and can serve as an active and stable water oxidation catalyst under both electrochemical and photochemical reaction conditions, owing to its unique structural features. In the electrochemical water oxidation, this catalyst affords a current density of 10 mA cm(-2) (a value related to practical relevance) at an overpotential of ∼0.40 V. Moreover, with the assistance of a sensitizer [Ru(bpy)3](2+) (bpy = 2,2'-bipyridine), this nanomaterial can catalyze water oxidation reactions under visible light irradiation with an O2 evolution rate of ∼12 218 μmol g(-1) h(-1). Our results suggest that delicate nanostructuring can offer unique advantages for developing efficient water oxidation catalysts.

In the past two decades considerable efforts have been concentrated on the use of II-VI semiconductor nanocrystals (NCs) as luminescent materials.[1] Owing to quantum-confinement effects, the optical properties of these nanocrystals (quantum dots) can be tuned by varying the crystal size.[2]Efficient red-or green-light emitters have been prepared containing zinc (cadmium) sulfide (selenide) II-VI NCs, [3] whereas the preparation of blue-emitting NCs of these compounds has not been as successful.[4] In addition, the involvement of Cd, S, and Se in these luminescent systems may cause toxicity and pollution problems, and sulfides or selenides are intrinsically less-resistant to oxidation by the O 2 in air.As one of the group of II-VI semiconductors, ZnO has attracted increasing attention recently because it is nontoxic, less expensive, and chemically stable towards air. However, its nanoscale crystals tend to aggregate or to undergo Ostwald ripening [5] because of their high surface energy. To stabilize NCs, appropriate surface modifications are usually necessary.[6] We have reported a facile sol-gel approach for the preparation of PEGME-modified (PEGME = poly(ethylene glycol) methyl ether) ZnO NCs with size-dependent photoluminescence (PL) and a high quantum yield (QY) of about 30 % at room temperature.[7] These ZnO NCs are stable in solution, but they still undergo Ostwald ripening upon thermal treatment or aging without the protection of LiOH in the solvent-free state. Xia and co-workers recently also obtained a polymer-stabilized nano-ZnO with remarkable blue PL.[8] However, only blue-emission was observed for this luminescent system and the origin of the emission was not very clear.Further stabilization of the NCs can be achieved if they are protected by charged species, such as alkyl ammonium cations, because the charges repel each other, thereby more effectively preventing the particles from undergoing aggregation or Ostwald ripening.

Mesoporous TiO(2) spheres with a large surface area and rich surface hydroxyl groups have been prepared through a light-driven synthetic strategy, and the as-prepared mesoporous material is able to convert urea to carbon nitride efficiently under a mild condition.

No abstract