Construction of ultra-low platinum-loaded metal-organic framework-on-metal-organic framework with...

MOF-on-MOF heterostructure materials integrate two or more MOFs with distinct structures to combine their advantages while creating synergistic effects. In this work, a PtCo MOF/UiO 66 composite was fabricated through hydrothermal-assisted epitaxial growth and electrodeposition. This process formed an amorphous/crystalline heterointerface with intertwined pore structures, which enhanced the surface contact area and overcame lattice mismatch. The loading of ultra-low-content Pt nanoparticles introduces abundant surface defects and microstructures, which enhance structural stability and providing additional electrochemical active sites. The interfacial electronic structure difference facilitated charge redistribution, with Co acting as an electron donor and Pt/Zr as electron acceptors, creating a built-in electric field that accelerated charge transfer and enhanced conductivity. As a result, the PtCo MOF/UiO 66 electrode delivered an outstanding specific capacity of 824.3C g^-1 at 1 A g^-1, while the assembled hybrid supercapacitor achieved a maximum energy density of 104.2 Wh kg^-1 and remarkable cycling stability (93.3 % retention after 10,000 cycles at 40 A g^-1). Additionally, when employed as a hydrogen evolution reaction electrocatalyst, the material required only 147 mV overpotential to reach 10 mA cm^-2. This work highlights the great potential of MOF-on-MOF heterostructures for dual-functional energy storage and conversion applications, offering new design strategies for advanced electrode materials.