Fig S1 ~ Fig S7

Fig. S1 SEM images of sandpapers with 5 different grit numbers Fig. S2 PSD examples for several resentative surfaces Fig. S3 in-operando measurement of thermal gradient and triboelectricity during the TENG operation. Fig. S4 The SEM image of FTO Fig. S5 Current evolution behavior of TENGs depending on the templates. Fig. S6 The working protocols of TENG. Fig. S7 Fig. S7 KPFM images