▎ 摘　　要

NOVELTY - Metal-organic framework-based catalyst comprises metal salts, and a carbon framework doped with nitrogen, where the metal salt is bonded to a carbon atom of the framework. USE - The metal-organic framework-based catalyst is used for a composition for 3D printing. The composition is used for a 3D printed electrode for sensing oxygen (all claimed). The electrode is used for sensing gases and dissolved oxygen. The electrode is used for on-site analysis, and is used for detecting oxygen present in a wide range of concentrations in medicine, environment, and various applications. ADVANTAGE - The 3D oxygen sensing electrode is manufactured easily and rapidly at a low cost by using a trace amount of noble metal, by a polymer/graphene/nanocatalyst composition prepared by 3D printing and nanocatalyst synthesis on the basis of a metal-organic framework (MOF). The 3D oxygen sensing electrode is capable of selectively sensing gases and dissolved oxygen and exhibits long-term stability. The catalyst is inexpensive and has excellent selective catalytic reaction and stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: a composition for three-dimensional (3D) printing comprising polymer, carbon, and the metal-organic framework-based catalyst; a 3D printed electrode for sensing oxygen using the composition for 3D printing; and a metal-organic framework-based catalyst preparation method comprising preparing a carbon precursor by adding an aldehyde solution to a compound solution containing nitrogen and performing hydrothermal synthesis, calcining the carbon precursor under nitrogen condition to prepare a nitrogen-doped carbon framework (NC), and reacting the NC-containing solution and the metal solution with a microwave.