Growth of the metal–organic framework ZIF-67 on cellulosic substrates for triboelectric nanogenerators

Abstract

Metal–organic frameworks (MOFs) are porous crystalline materials with a metal ion coordinated to a ligand molecule. Recently, MOFs are being explored extensively for energy harvesting via triboelectrification. However, the majority of MOFs are brittle and hard to grow, thus leading to poor device stability and flexibility. Herein, the growth of ZIF-67 MOF is achieved on a cellulosic filter paper (CFP) and cotton fabric (CF) separately to use as the active layer in a TENG. The grown ZIF-67 MOFs were used for the fabrication of CFP-TENG and CF-TENG in vertical contact separation mode. The CF-TENG device exhibited a high durability with no significant change in the electrical output for a period of 14 000 s. Additionally, the device generated a maximum electrical output of 60 V and 3 μA with an output power density of 5 mW m⁻² at a load resistance of 800 MΩ. The robustness of the MOF grown on cotton fabric was demonstrated by fabricating a contact separation and rotating TENG device. The rotating TENG device produced an output voltage of ∼100 V and current of 3.5 μA, thus confirming the strong adherence of MOFs on the fabric. The CF-TENG was demonstrated for powering electronics via flexible circuits and for biomechanical energy harvesting by utilising finger tapping, hand tapping, jogging and running movements.