Impregnation of Cellulose Fibers with Copper Colloids and Their Processing into Electrically Conductive Paper

The use of biodegradable and nontoxic cellulose as a renewable alternative to plastic in electronics is a promising way to decrease the environmental pollution. Unfortunately, cellulose lacks one of the key properties for such applications, namely, electrical conductivity. Here, we report the complete impregnation of macroscopic cellulose fibers with copper colloids using a simple, fast, gram-scalable, electroless, and noble metal catalyst-free liquid-phase approach. By varying the stepwise addition of a precursor to the ongoing reaction, the amount of copper colloids inside the cellulose fibers and thus the electrical conductivity of the final product can be controlled. A simple vacuum filtration makes it possible to process the copper-impregnated fibers into self-supporting, paper-like membranes, whose electrical conductivity can be further improved by slight pressing. The fiber-like morphology in these papers is fully preserved after pressing, leading to a high in-plane conductivity of 10′105 ± 751 S/m. By equipping cellulose with electrical conductivity, the functional properties of this renewable material are significantly extended, making it now attractive for a wide range of emerging applications in electronics and electrocatalysis.