Platinum-Tellurium Heterojunction Nanosheet Assemblies for Efficient Direct Formic Acid Electrooxidation Catalysis.

Two-dimensional (2D) heterojunction nanomaterials offer exceptional physicochemical and catalytic properties, thanks to their special spatial electronic structure. However, synthesizing morphologically uniform 2D platinum (Pt)-based metallic nanomaterials with diverse crystalline phases remains a formidable challenge. In this study, we have achieved the successful synthesis of advanced 2D platinum-tellurium heterojunction nanosheet assemblies (Pt x -PtTe 2 HJNSAs, x = 0, 1, 2), seamlessly integrating both trigonal PtTe 2 ( t -PtTe 2 ) and cubic Pt ( c -Pt) phases. By enabling efficient electron transport and leveraging the specific electron density present at the heterojunction, the Pt 2 -PtTe 2 HJNSAs/C demonstrated exceptional formic acid oxidation reaction (FAOR) activity and stability. Specifically, the specific and mass activities reached 8.4 mA cm -2 and 6.1 A mg Pt -1 , which are 46.7 and 50.8 times higher than those of commercial Pt/C, respectively. Impressively, aberration-corrected high-angle annular dark field scanning transmission electron microscopy (AC-HAADF-STEM) revealed a closely packed arrangement of atomic layers and a coherent intergrowth heterogeneous structure. Density functional theory (DFT) calculations further indicated that rearrangement of electronic structure occurred on the surface of Pt 2 -PtTe 2 HJNSAs resulting in a more favorable dehydrogenation pathway and excellent CO tolerance, beneficial for performance improvement. This work inspires the targeted exploration of Pt-based nanomaterials through 2D heterostructure design, leading to an important impact on fuel cell catalysis and beyond.