Ag Nanoparticle-Enabled Electroless Deposition of Ni on Mine-Formaldehyde Sponges for Oil–Water Separation, Piezoresistive Sensing, and Electromagnetic Shielding

Porous materials have attracted great attention in recent years, and a variety of surface modification techniques have been developed. Herein, a layer of non-noble metal nickel was deposited onto mine-formaldehyde sponges by an electroless depositing process which uses poly(4-vinylpyridine) as an assisted functional layer and Ag nanoparticles as catalytic seeds for the metal growth. The hydrophobic metallized sponges can selectively adsorb oils from oil–water mixtures and achieve dynamic oil–water separation. The as-made metallized sponges also feature good mechanical stability, flexibility, and conductivity. A piezoresistive sensor based on the metallized sponges is fabricated, which exhibits excellent sensing performance with sensitivity of 212.9 kPa–1 in the range of less than 2 kPa. The sensors can be further applied to monitor dynamic postures of human body. Moreover, the metallized sponges show great potential as electromagnetic interference shielding and thermal conductive materials. This work provides a facile and efficient way to introduce a non-noble metal to porous materials toward multifunctional applications in fields of oil–water separation, wearable electronics, and electromagnetic shielding equipment.