84 research outputs found
Chemical Vapor Deposition of Hollow Graphitic Spheres for Improved Electrochemical Durability
The wet-chemical synthesis of hollow graphitic spheres, a highly defined model catalyst support for electrocatalytic processes, is laborious and not scalable, which hampers potential applications. Here, we present insights into the chemical vapor deposition (CVD) of ferrocene as a simple, scalable method to synthesize hollow graphitic spheres (HGScvd). During the CVD process, iron and carbon are embedded in the pores of a mesoporous silica template. In a subsequent annealing step, iron facilitates the synthesis of highly ordered graphite structures. We found that the applied temperature treatment allows for controlling of the degree of graphitization and the textural properties of HGScvd. Further, we demonstrate that platinum loaded on HGScvd is significantly more stable during electrochemical degradation protocols than catalysts based on commercial high surface area carbons. The established CVD process allows the scalable synthesis of highly defined HGS and therefore removes one obstacle for a broader application
Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction
Catalysts for oxygen reduction and evolution reactions are at the heart of
key renewable energy technologies including fuel cells and water splitting.
Despite tremendous efforts, developing oxygen electrode catalysts with high
activity at low costs remains a grand challenge. Here, we report a hybrid
material of Co3O4 nanocrystals grown on reduced graphene oxide (GO) as a
high-performance bi-functional catalyst for oxygen reduction reaction (ORR) and
oxygen evolution reaction (OER). While Co3O4 or graphene oxide alone has little
catalytic activity, their hybrid exhibits an unexpected, surprisingly high ORR
activity that is further enhanced by nitrogen-doping of graphene. The
Co3O4/N-doped graphene hybrid exhibits similar catalytic activity but superior
stability to Pt in alkaline solutions. The same hybrid is also highly active
for OER, making it a high performance non-precious metal based bi-catalyst for
both ORR and OER. The unusual catalytic activity arises from synergetic
chemical coupling effects between Co3O4 and graphene.Comment: published in Nature Material
Chemical Vapor Deposition of Hollow Graphitic Spheres for Improved Electrochemical Durability
The wet-chemical synthesis of hollow graphitic spheres, a highly defined model catalyst support for electrocatalytic processes, is laborious and not scalable, which hampers potential applications. Here, we present insights into the chemical vapor deposition (CVD) of ferrocene as a simple, scalable method to synthesize hollow graphitic spheres (HGScvd). During the CVD process, iron and carbon are embedded in the pores of a mesoporous silica template. In a subsequent annealing step, iron facilitates the synthesis of highly ordered graphite structures. We found that the applied temperature treatment allows for controlling of the degree of graphitization and the textural properties of HGScvd. Further, we demonstrate that platinum loaded on HGScvd is significantly more stable during electrochemical degradation protocols than catalysts based on commercial high surface area carbons. The established CVD process allows the scalable synthesis of highly defined HGS and therefore removes one obstacle for a broader application
Part 2—Impacts of Electrolyte and Reactant Size on Structure Sensitivity in Electrocatalysis: A Geometric Approach
Best Practices and Testing Protocols for Benchmarking ORR Activities of Fuel Cell Electrocatalysts Using Rotating Disk Electrode
Corrosion Behavior of Platinum in Aqueous H2SO4 Solution: Part 1—Influence of the Potential Scan Rate and the Dissolved Gas
The Effect of the Voltage Scan Rate on the Determination of the Oxygen Reduction Activity of Pt/C Fuel Cell Catalyst
Catalytic Duality of Platinum Surface Oxides in the Oxygen Reduction and Hydrogen Oxidation Reactions
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