Direct Growth of Zn–Co MOF Thin Films for High-Performance Triboelectric Energy Harvesting and Self-Powered Devices

Triboelectric nanogenerators (TENGs) are promising for harvesting low-frequency mechanical energy, yet their performance is often limited by the low charge density and modest dielectric properties of commonly used polymer triboelectric materials. Although metal–organic frameworks (MOFs)- based TENGs have been explored to enhance performance, most MOF-based TENGs use MOFs as filler materials, thereby restricting their intrinsic surface functionality and triboelectric nature. Herein, we report the direct growth of bimetallic Zn–Co MOF thin films on aluminum substrates using the hydrothermal method and use them as standalone triboelectric layers in a vertical contact–separation TENG configuration. Systematic variation of the Zn:Co molar ratio enabled modulation of surface morphology and triboelectric performance. Surface potential measurements confirmed the tribopositive nature of the Zn–Co MOF film and experimentally established its relative position in the triboelectric series. Among the investigated compositions, the Zn:Co (1:3) film exhibited optimal performance, delivering an open-circuit voltage of 490 V, a short-circuit current of 125 μA, and a peak power density of 10.42 W/m2 at 1 MΩ load resistance. The enhanced performance may be attributed to the combined effects of bimetallic composition and increased effective contact area. The best-performing TENG device powered a series-connected 480 light-emitting diodes and portable electronic devices using an energy storage element, demonstrating its practical applicability. The present work establishes a simple and scalable method for directly integrating bimetallic MOF thin films as an active triboelectric layer for high-performance triboelectric energy harvesting systems and self-powered device applications.