  The 3D printing technology offers an innovative approach for developing
energy storage devices to create facile and low-cost customized electrodes for
modern electronics. Generating electric potential by moving a droplet of ionic
solution over two-dimensional (2D) materials is a novel method for rain energy
harvesting. This work demonstrated a liquid-solid contact electrification-based
3D printed nanogenerator where raindrop passes through the positively charged
ultrathin Gadolinium Telluride (Gd2Te3) sheets. Experimental results showed
that voltage as high as ~0.6 V could be generated by moving a droplet of ionic
solution on the decorated 3D printed nanogenerator. The output efficiency of
the nanogenerator is increased ~400% by enhancing the surface area of copious
3D printed porous structures. Density Functional Theory (DFT) calculations are
done, revealing that the high electrical conductivity of (112) surface of
Gd2Te3 is due to the p-type charge carriers. Additionally, we illustrate the
enhancement of the output performance (~0.8V) by using a graphite rod and
arbitrarily manipulating the surface charge. Therefore, this work can open up a
new avenue to advance scientific research of Blue energy harvesting and tackle
the energy crisis.
