Programming Bifunctional\nMetal–Organic Frameworks\nto Integrate Multiple Triboelectric Nanogenerators for Green Electronics\ntoward Effective Self-Powered Photocatalytic System

Programming and synthesizing bifunctional materials for\nregulating\nthe output of triboelectric nanogenerators (TENGs) and their photocatalytic\nefficiency is a promising strategy for energy harvesting to build\nself-powered systems. Herein, we tackle this challenge by introducing\nmetal–organic frameworks (MOFs) as molecular catalysts and\ntriboelectric layers for self-powered photocatalytic systems. A zeolite-like\nmixed-valence MOF (<b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1</b>) and a ladder-structured\nMOF (<b>Cu</b><sup><b>II</b></sup><b>-2</b>) were\nobtained through structural transformation. Due to the excellent charge-trapping\ncapability and surface potential of <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1</b>, the\noutputs of <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1-TENG</b> (a short-circuit current\n(<i>I</i><sub>sc</sub>) of 30.4 μA and an open-circuit\nvoltage (<i>V</i><sub>oc</sub>) of 524.1 V) were significantly\nsuperior to those of <b>Cu</b><sup><b>II</b></sup><b>-2-TENG</b>. The incorporation of <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1</b> with\nethylcellulose (EC) to form <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1@EC</b> composite\nfilms greatly improved the TENG outputs, and the 10% <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1@EC-TENG</b> offered the maximum <i>I</i><sub>sc</sub> (57.2 μA) and <i>V</i><sub>oc</sub> (986.8\nV). Furthermore, multiple 10% <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1@EC-TENG</b> devices\nwere integrated in parallel to assemble multiple TENG devices (<b>M-TENG</b>) to harvest biomechanical energy, which displayed significant\npotential to continuously power blue LEDs, generating blue-light irradiation\nto trigger the photocatalytic C(sp)–H/Si–H cross-coupling\nreactions of aromatic alkyne and trimethylsilane for alkynylsilane\nover the photocatalysts <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1</b> and <b>Cu</b><sup><b>II</b></sup><b>-2</b>. The results revealed that <b>Cu</b><sup><b>I</b></sup><b>Cu</b><sup><b>II</b></sup><b>-1</b> achieved a cooperative effect on remarkable\ncatalytic selectivity and activity. This work demonstrates that bifunctional\nMOFs can serve as friction electrode materials for the large-scale\nintegration and assembly of MOF-based TENG, and photocatalysts for\nachieving self-powered photocatalytic systems.