Spontaneous occurrence of liquid-solid contact electrification in nature: Toward a robust triboelectric nanogenerator inspired by the natural lotus leaf

The successive process of contact and detachment of aqueous liquid from the solid surface with its resultant net electrical charge generation is termed as discrete liquid-solid contact electrification, which is unobtrusively ubiquitous in our daily life. So far, the natural occurrence of discrete liquid-solid contact electrification on surfaces in nature has not been investigated and reported despite the beneficial characteristics of such surfaces. This study firstly reveals the existence of the discrete liquid-solid contact electrification phenomenon and concomitant net electrical charge generation on the natural lotus leaf surface. To advantageously utilize the generated net electrical charges, for the first time, the naturally occurring surface is directly employed to fabricate the natural lotus leaf-TENG, called the LL-TENG. The further investigation about the electricity generation is continued by altering contact material of the LL-TENG to fluoropolymer while maintaining the lotus leaf's superior surface characteristics, in a simple and cost-effective manner via thermal nanoimprinting. The artificially modified TENG not only significantly increases the amount of the generated electricity, but also shows sustained electrical output performance even after 1 month of exposure in the external dusty environment with the help of the outstanding lotus effect.