Fig. 4

(a) PVP-AgNPs UV–Vis spectrum from day 0 (Pink line) and after 326 days (blue line). (b,c) TGA analysis of PVP-AgNPs stability under an oxidizing atmosphere. (b) Mass loss due to water evaporation in the range of 16 °C to 140 °C. (c) Close-up of the interval between 200 and 500 °C showing the loss of mass due to degradation of PVP-AgNPs.