Facile Templateless Fabrication of a Cobalt Oxyhydroxide Nanosheet Film with Nanoscale Porosity as an Efficient Electrocatalyst for Water Oxidation

Abstract

The development of efficient catalysts for water oxidation is widely required because the efficiency of fuel production by artificial photosynthesis is severely limited by the sluggish kinetics of water oxidation. A unique CoO(OH) nanosheet (CoO (OH)-NS) film having porosity in nanoscale dimensions has been synthesized by a facile electrochemical technique without the assistance of any template. The SEM image exhibited that the film is composed of nanosheets that are well scattered and formed uniformly by unidirectional vertical growth on the electrode surface. The TEM image showed a highly porous nanostructure with randomly oriented nanopores (with a dimension of ca. 5 nm) inside the nanosheet. The HRTEM image revealed that flat-shaped rectangular CoO(OH) nano-crystals (ca. 2-3 nm) were randomly stacked together to form the nanosheet and interspaces between the nanocrystals for the nanoporous structure. The specific surface area of the CoO (OH)-NS film was 92 m 2 g À1 , which is higher than that (43 m 2 g À1 ) of a CoO(OH) nanoparticle (CoO(OH)-NP) film that is prepared by a chemical procedure as a reference sample. A superior electrocatalytic performance for water oxidation was observed for CoO(OH)-NS electrode compared with the CoO(OH)-NP electrode. This result originates from the large accessible surface-to-volume ratio of the unique porous nanosheet structures, which provides a large number of electroactive water oxidation sites at the electrolyteÀCoO(OH) interface.[a] Dr.

Concisely Synthesized FeNiWOx Film as a Highly Efficient and Robust Catalyst for Electrochemical Water Oxidation

“…Conventionally, OER anodes have been prepared by various physical and chemical techniques, including hydrothermal, 36 electrodeposition, 39,40 electrophoresis, 41−43 spin coating, 44,45 drop-casting, 46 self-assembly, 47 dip coating, 48 screen printing, 49 chemical bath deposition, 50 photochemical formation, 51 and pulsed laser deposition. 19 However, facile and energyconserving preparation techniques of the OER anodes are absolutely needed in view of their extensive availability in a nod to current preparation methods of OER anodes using various physical and chemical techniques.…”

“…Conventionally, OER anodes have been prepared by various physical and chemical techniques, including hydrothermal, electrodeposition, , electrophoresis, − spin coating, , drop-casting, self-assembly, dip coating, screen printing, chemical bath deposition, photochemical formation, and pulsed laser deposition . However, facile and energy-conserving preparation techniques of the OER anodes are absolutely needed in view of their extensive availability in a nod to current preparation methods of OER anodes using various physical and chemical techniques. ,,− Herein, we have amazingly found that loading-controllable single- and mixed-metal oxide films adhered rigidly on various electrode substrates are easily prepared from precursor solutions or suspensions containing corresponding metal salts in methanol/1-methyl imidazole (MeIm) mixed solvents. Material hunting for superior OER anodes has been performed by preparing a variety of single- and mixed-metal oxide films using this method.…”