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.

Spatially separating redox centers on 2D carbon nitride with cobalt single atom for photocatalytic H2O2 production.

Abstract: Redox cocatalysts play crucial roles in photosynthetic reactions, yet simultaneous loading of oxidative and reductive cocatalysts often leads to enhanced charge recombination that is detrimental to photosynthesis. This study introduces an approach to simultaneously load two redox cocatalysts, atomically dispersed cobalt for improving oxidation activity and anthraquinone for improving reduction selectivity, onto graphitic carbon nitride (C3N4) nanosheets for photocatalytic H2O2 production. Spatial separation of oxidative and reductive cocatalysts was achieved on a two-dimensional (2D) photocatalyst, by coordinating cobalt single atom above the void center of C3N4 and anchoring anthraquinone at the edges of C3N4 nanosheets. Such spatial separation, experimentally confirmed and computationally simulated, was found to be critical for enhancing surface charge separation and achieving efficient H2O2 production. This center/edge strategy for spatial separation of cocatalysts may be applied on other 2D photocatalysts that are increasingly studied in photosynthetic reactions.

Structural Chemistry of Co-Mo-Alumnina Catalysts

Abstract: The structural chemistry of Co-Mo-alumina hydrodesulfurization catalysts has been critically reviewed in this article. The location and nature of cobalt in the sulfided catalysts has been discussed. Small MoS2, crystallites (10 to 30 A) that occur on the surface of a sulfided sample are unstable due to the high, net negative charge on the sulfur ions on their edges. They incorporate cations like Co2+ at the edges of the MoS2 sheet (not intercalated between the sheets) and attain stability. It is shown that for the range of crystallito sizes of MoS, in these systems, a maximum of one Co ion can be incorporated per two Mo ions in this manner. Cobalt thus lends structural stability to the MoS2, crystallites and suppresses the excessive formation of anion vacancies at crystallite edges. Molybdenum sulfide crystallites on sulfided Mo-A12O3, lacking this stabilizing influence of cobalt, lose excess sulfur, leading to the creation of a larger concentration of multiple anion vacancies at their edges. The...

High Alcohols Synthesis via Fischer–Tropsch Reaction at Cobalt Metal/Carbide Interface

Abstract: Utilization of nonprecious transition metals for high alcohols synthesis is of a great importance in heterogeneous catalysis. We synthesized successfully cobalt metal-carbide (Co–Co2C) catalysts, which present remarkable activity and selectivity for high alpha-alcohols via the Fischer–Tropsch reaction. The formation of the stable cobalt carbide and the Co–Co2C interface are found to be essential for the observed reactivity. Density functional theory calculations show that Co2C is highly efficient for CO nondissociative adsorption, behaving as noble-metal-like, whereas the Co metal is highly active for CO dissociative adsorption and the subsequent carbon-chain growth. The interface between the cobalt metal and its carbide phase, as well as the dual sites available at the interface for facile CO insertion to hydrocarbon, could be used to rationalize the design of the nonprecious transition metal catalysts for the oxygenates in syngas conversion.