Polyoxometalate-Modified g-C3N4 Composites with High Work Function for Triboelectric Nanogenerators

Designing friction materials with high electron storage capacity, high work function, low cost, and high stability is an important method to improve the output performance of a triboelectric nanogenerator (TENG). Here, we report two kinds of friction materials based on Keggin-type polyoxometalates (POMs)-modified graphite carbon nitride (g-C3N4), namely, g-C3N4@PMo12 and g-C3N4@PW12, and form TENG with commercial indium tin oxide/poly(ethylene terephthalate) (ITO/PET) electrodes. The performance test shows that the g-C3N4@PMo12 TENG device exhibits a high output voltage of about 78 V, a current of about 657 nA, and a transfer charge of about 15 nC, which is more than 3 times higher than that of unmodified TENG. This performance improvement is attributed to the fact that POM loaded on the surface of g-C3N4 can be used as a shallow electron trap to increase the electron storage capacity through electron interaction and to increase the charge density on the surface of the material by increasing the work function of the composite. This work not only broadens the choices of TENG friction materials but also offers a practical means of enhancing TENG's output performance.