Platinum Nanoparticle Inclusion into a Carbonized Polymer of Intrinsic Microporosity: Electrochemical Characteristics of a Catalyst for Electroless Hydrogen Peroxide Production

• Published in: Nanomaterials (Basel, Switzerland) Switzerland), 2018-07, Vol.8 (7), p.542
• Main Authors: Adamik, Robert K, Hernández-Ibáñez, Naiara, Iniesta, Jesus, Edwards, Jennifer K, Howe, Alexander G R, Armstrong, Robert D, Taylor, Stuart H, Roldan, Alberto, Rong, Yuanyang, Malpass-Evans, Richard, Carta, Mariolino, McKeown, Neil B, He, Daping, Marken, Frank
• Format: Article
• Language: English
• Subjects: Acids; bifunctional catalysis; Carbon; Carbonization; Catalysis; Catalysts; Chemical synthesis; Chemistry; Composite materials; Electrochemistry; Fuel cells; heterocarbon; Hydrogen peroxide; Membranes; Microporosity; Molecular structure; Nanoparticles; Nitrogen; Oxidation; Oxygen; peroxide; Platinum; Polymers; Powder injection molding; Reduction; Surface area; Vacuum; voltammetry; Water purification
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano8070542

The one-step vacuum carbonization synthesis of a platinum nano-catalyst embedded in a microporous heterocarbon (Pt@cPIM) is demonstrated. A nitrogen-rich polymer of an intrinsic microporosity (PIM) precursor is impregnated with PtCl₆ to give (after vacuum carbonization at 700 °C) a nitrogen-containing heterocarbon with embedded Pt nanoparticles of typically 1⁻4 nm diameter (with some particles up to 20 nm diameter). The Brunauer-Emmett-Teller (BET) surface area of this hybrid material is 518 m² g (with a cumulative pore volume of 1.1 cm³ g ) consistent with the surface area of the corresponding platinum-free heterocarbon. In electrochemical experiments, the heterocarbon-embedded nano-platinum is observed as reactive towards hydrogen oxidation, but essentially non-reactive towards bigger molecules during methanol oxidation or during oxygen reduction. Therefore, oxygen reduction under electrochemical conditions is suggested to occur mainly via a 2-electron pathway on the outer carbon shell to give H₂O₂. Kinetic selectivity is confirmed in exploratory catalysis experiments in the presence of H₂ gas (which is oxidized on Pt) and O₂ gas (which is reduced on the heterocarbon surface) to result in the direct formation of H₂O₂.