Composite layers, methods for their manufacture and uses thereof
A composite layer of carbon nanotubes and metal such as copper is formed by electrodeposition. The layer has a thickness of at least 10 μm. The carbon nanotubes are distributed through the layer and are present in the layer at a volume fraction of at least 0.001 vol % and at most 65 vol %. The volume fraction is based on the total volume of the metal and carbon nanotubes and not including any pore volume. The carbon nanotubes are substantially uniformly plated with the metal. The composite layer has a density ratio satisfying Player Pmetal ≤0.35 where player is the bulk density of the composite layer of thickness of at least 10 μm, including any voids that are present in the composite layer and pmetal is the volumetric mass density material property of the metal. The composite layer is of use in evaporation-condensation apparatus, as an active material layer in an electrochemical device or in an electroforming process.
1. A process for manufacturing a composite layer of carbon nanotubes and metal, the process comprising the steps:
providing carbon nanotubes;
dispersing the carbon nanotubes in an electrolyte solution;
providing a working electrode and a counter electrode comprising the metal, each in contact with the electrolyte; and
electroplating the working electrode with the carbon nanotubes and metal to grow the composite layer at a rate of change of thickness of the composite layer of at least 10 μm/min to a thickness of at least 10 μm;
wherein, for at least a part of the process, the composite layer of thickness of at least 10 μm has a density ratio satisfying:
ρ
layer
ρ
metal
≤
0.35
where p layer is the bulk density of the composite layer of thickness of at least 10 μm, including any voids that are present in the composite layer and p metal is the volumetric mass density material property of the metal.
2. The process according to claim 1 wherein, during electroplating the working electrode with the carbon nanotubes and metal to grow the composite layer at a rate of change of thickness of the composite layer of at least 10 μm/min, the rate of change of area density is at most 0.8 kg/m 2 /min.
3. The process according to claim 1 wherein the carbon nanotubes are functionalised with at least one selected from the group consisting of:
Hydroxyl, Phenol, Carbonyl, Carboxylate, Carboxyl, Phosphate, Phosphono, Sulfonic acid, Sulfhydryl, Sulfide, Disulfide, Amino, Quaternary ammonium.
4. The process according to claim 3 wherein the degree of functionalisation of the carbon nanotubes is at least 1 wt %.
5. The process according to claim 1 wherein the electrolyte, at least at the start of deposition, contains at least 0.0001 wt % carbon nanotubes.
6. The process according to claim 1 wherein the electrolyte, at least at the start of deposition, contains not more than 0.2 wt % carbon nanotubes.
7. The process according to claim 1 wherein the electrolyte, at least at the start of deposition, has a concentration of the metal in the range 0.05-1.2 M.
8. An electroforming process comprising the steps:
carrying out a process according to claim 1 to manufacture a composite layer of carbon nanotubes and metal;
carrying out additional electroplating of a metal into the composite layer to produce an electroformed product.