The present technology allows to produce thin metallic silver films/coatings (0.5 – 5 ìm thickness) with open nanopores. A silver containing ink formulation is the key part of the invention which can be applied on basically any substrate by printing, roll-coating or spraying and be transformedinto a highly conductive and highly porous silver film by a lowtemperature treatment. Such nanoporous silver films provide a high specific surface area and goodelectrical conductivity. The nanoporous silver membranes can be used as filtration membranes with a cut-off range between 50 and 200 nm andwith high solvent or temperature stability. Specifically, filtration applications are promising which require electrical charging of the filtration membrane.
Background
Nanoporous metal films are characteristic for their high specific surface area and good electrical conductivity which is desired in catalytic applications.To date the preparation of such nanoporous metal films or coatings involve complex processing steps and vacuum deposition technologies. As an additional drawback,nanoporous metal films prepared by conventional techniques usually exhibit cracks.The invention is based on composite nanoparticles containing silver andcalcium carbonate. Corresponding inks/dispersions of these particles allow the deposition of nanocomposite films on a substrate by applying and drying the ink (Fig. 1). A heat treatment for 15min at 170°C results in sintering of silver nanoparticles and finally the deposited nanocomposite layer exhibits two percolating networks of metallic silver and calcium carbonate. The formation of nanopores is facile and done by washing away the calcium carbonate. The formation of nanopores is facile and done by washing away the calcium carbonate template in a mild acidic.
Patent Status
-Patent pending
Features & Benefits
-High electrical conductivity
-High surface area
-Defect- and crack-free
-Operating temperature up to 200°C
-Variable film thickness of 0.5 – 5 μm
-Pore size adjustable between 50and 200 nm, leading to a correspondingfiltration cut-off-No vacuum deposition technologyrequired
Field of Application
Filtration applications:-Biological materials such as bacteriaand viruses down to 50 nm in size-Organic solvents-Selective filtration of charged species(e.g. proteins) by voltage assisted techniques.
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