Synthesis of nickel-containing metal-polymer nanocomposites and their use as a humidity sensor

In recent years, the synthesis of new gas-sensitive materials for resistive humidity sensors has attracted significant interest. In the present paper, nickel-containing metal-polymer nanocomposites were obtained by thermolysis of nickel itaconate (I) and its complexes with 2,2′-dipyridyl (II), 1,10-phenanthroline (III) and 4′-phenyl-2,2′:6′,2''-terpyridine (IV). The formed nanocomposites were characterized by FTIR, elemental analysis, EDX, SEM, TEM and XRD studies. The most common particle sizes are 28, 12.8, 10.7 and 12.3 nm for the thermolysis products of compounds I–IV respectively. The manufactured sensor samples have good sensitivity to air relative humidity (RH) of 3.24 %/%RH, 4.72 %/%RH, 2.18 %/%RH and 4.37 %/%RH for thermolysis products of compounds I–IV with the polymer binder polyacrylamide, respectively. The average initial resistance of the sensors is 4.54, 15.33, 20.8 and 35.75 MΩ, respectively. Due to the high porosity and moisture absorption of the film, the maximum sensitivity was about 0.003 MΩ/%RH, which indicates a fairly effective behavior of the film with respect to humidity. The response times were 27, 25, 33, 30 s, and the recovery time 47, 44, 51, 49 s, respectively, and repeating the experiment resulted in 87–92 % reproducible results. The fabricated sensors have great potential for use as a humidity sensing element in sensors that can be used for humidity monitoring.