Nanoporous metal foam gas and fluid filters

A method of constructing a free-standing metal foam, the method comprising:

• electrochemically depositing a selected metal into one or more nanoporous templates to form metal nanowires employing a first electrolyte solution containing the selected metal;
• dissolving the one or more nanoporous templates in a selected solution;
• replacing some or all of the selected solution with water to produce a nanowire/water suspension;
• freezing the nanowire/water suspension;
• sublimating the water portion of the frozen nanowire/water suspension to produce the free-standing metal foam comprising a plurality of nanowires, wherein the density of the plurality of nanowires is increased;
• and further electrochemically depositing more of the selected metal, wherein the further electrochemically depositing comprises:
• adjusting the amount of the selected metal deposited to vary the diameter of the plurality of nanowires,
• adjusting a pH of a second electrolyte solution containing the selected metal, and
• depositing the selected metal upon and throughout the free-standing metal foam so as to coat the plurality of nanowires of the free-standing metal foam, resulting in thickening of the free-standing metal foam around individual nanowires of the plurality of nanowires, as well as at intersections of multiple nanowires of the plurality of nanowires, thereby enhancing the free-standing metal foam's mechanical stability to enable the free-standing metal foam to withstand greater compressive stress than before the further electrochemically depositing step.