Triboelectric nanogenerator with nanostructured metal surface using water-assisted oxidation

Highlights: • A triboelectric nanogenerator (TENG) with a micro and nanostructures at the interface is fabricated based on the water-assisted oxidation (WAO) process. • Optimal fabrication condition is determined to maximize the effective contact area of the TENG. • Practicality of the WAO-based TENGs is demonstrated by its application to a wind-based TENG. The performance of a triboelectric nanogenerator (TENG) was effectively enhanced by forming nanostructures at the contacting interface. The contacting interface usually consists of metal and polymer surface, but the formation of nanostructures have only been actively studied for the polymer so far. In this work, a simple and effective route to forming nanostructures on the metal surface is proposed, using a water-assisted oxidation (WAO) process. The one-step WAO process requires only hot water without any complicated equipment and treatment. Using the WAO process, densely packed micro and nanostructures were successfully formed on three target metal surfaces: aluminum, copper, and zinc. The output power of the TENG was enhanced after the nanostructure formation because of the increased contact area. The influence of the process conditions on the nanostructure morphology was additionally analyzed to maximize the output power. The simple and low-cost WAO process is advantageous in terms of practicality.