Topic
Cobalt
About: Cobalt is a research topic. Over the lifetime, 69899 publications have been published within this topic receiving 1242058 citations. The topic is also known as: Co & Element 27.
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TL;DR: In this article, high-resolution X-ray photoemission of CoO and Co3O4 has been studied and the properties of the Co 2p 3 2, 2p 1 2, and 3s regions, their band shapes and widths, the associated shake-up structure, and the O(1s) and O(2s) BE's were examined.
811 citations
TL;DR: In this paper, magnetic nanoparticles of cobalt ferrite have been synthesized by wet chemical method using stable ferric and cobalt salts with oleic acid as the surfactant.
784 citations
TL;DR: This work represents the first mechanistic study of amorphous phases of binary and ternary metal oxides for use as water oxidation catalysts, and provides the foundation for the broad exploration of other mixed-metal oxide combinations.
Abstract: Photochemical metal–organic deposition (PMOD) was used to prepare amorphous metal oxide films containing specific concentrations of iron, cobalt, and nickel to study how metal composition affects heterogeneous electrocatalytic water oxidation. Characterization of the films by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy confirmed excellent stoichiometric control of each of the 21 complex metal oxide films investigated. In studying the electrochemical oxidation of water catalyzed by the respective films, it was found that small concentrations of iron produced a significant improvement in Tafel slopes and that cobalt or nickel were critical in lowering the voltage at which catalysis commences. The best catalytic parameters of the series were obtained for the film of composition a-Fe20Ni80. An extrapolation of the electrochemical and XPS data indicates the optimal behavior of this binary film to be a manifestation of iron stabilizing nickel in a higher oxidation level. This work ...
784 citations
TL;DR: In this paper, different supports (e.g. Al2O3, TiO2, SiO2 and ZrO2 modified SiO 2 or Al2 O3) and a variety of promoters, including noble metals and metal cations, were examined.
Abstract: Temperature programmed reduction (TPR) and hydrogen chemisorption combined with reoxidation measurements were used to define the reducibility of supported cobalt catalysts. Different supports (e.g. Al2O3, TiO2, SiO2, and ZrO2 modified SiO2 or Al2O3) and a variety of promoters, including noble metals and metal cations, were examined. Significant support interactions on the reduction of cobalt oxide species were observed in the order Al2O3>TiO2>SiO2. Addition of Ru and Pt exhibited a similar catalytic effect by decreasing the reduction temperature of cobalt oxide species, and for Co species where a significant surface interaction with the support was present, while Re impacted mainly the reduction of Co species interacting with the support. For catalysts reduced at the same temperature, a slight decrease in cluster size was observed in H2 chemisorption/pulse reoxidation with noble metal promotion, indicating that the promoter aided in reducing smaller Co species that interacted with the support. On the other hand, addition of non-reducible metal oxides such as B, La, Zr, and K was found to cause the reduction temperature of Co species to shift to higher temperatures, resulting in a decrease in the percentage reduction. For both Al2O3 and SiO2, modifying the support with Zr was found to enhance the dispersion. Increasing the cobalt loading, and therefore the average Co cluster size, resulted in improvements to the percentage reduction. Finally, a slurry phase impregnation method led to improvements in the reduction profile of Co/Al2O3.
770 citations
TL;DR: It is reported that cobalt-phosphorous-derived films (Co-P) can act as bifunctional catalysts for overall water splitting with 100% Faradaic efficiency, rivalling the integrated performance of Pt and IrO2.
Abstract: One of the challenges to realize large-scale water splitting is the lack of active and low-cost electrocatalysts for its two half reactions: H2 and O2 evolution reactions (HER and OER). Herein, we report that cobalt-phosphorous-derived films (Co-P) can act as bifunctional catalysts for overall water splitting. The as-prepared Co-P films exhibited remarkable catalytic performance for both HER and OER in alkaline media, with a current density of 10 mA cm−2 at overpotentials of −94 mV for HER and 345 mV for OER and Tafel slopes of 42 and 47 mV/dec, respectively. They can be employed as catalysts on both anode and cathode for overall water splitting with 100 % Faradaic efficiency, rivalling the integrated performance of Pt and IrO2. The major composition of the as-prepared and post-HER films are metallic cobalt and cobalt phosphide, which partially evolved to cobalt oxide during OER.
759 citations