Ultrathin nanoporous metallic films and their integration in sensors

Nanoporous metallic films (NPMFs), featuring an extensive surface area and a network of interconnected ligaments, are making a significant impact across various fields due to their unique physical and chemical properties, which are distinct from those of dense films. We fabricate ultrathin NPMFs that have a thickness of one ligament diameter (tens of nm) and introduce a facile method to transfer these films onto an alternative substrate, including nanostructured sensing materials. The method is simple and applicable to a wide spectrum of nanoporous metallic films. Unlike other methods, we can grow ultrapure films with a large number of metals and metal compositions. We apply our growth and transfer method to enhance the sensor performance of a metal oxide gas sensor. By transferring a NPMF onto Pt we increase the sensitivity and also reduce the required operating temperatures. Further, we describe how ultrathin nanoporous films composed of reactive and alloyed metals can be obtained, and thereby indicate how ultrathin, yet highly robust, NPMFs show promise for catalytic applications and sensors.