Preparation of Oxygen Reduction Catalyst Electrodes by an Efficient Electrodeposition Method on HNO3-Activated Carbon Paper

The proton exchange membrane fuel cell (PEMFC) is a promising energy conversion technology. The synthesis route of the cathode oxygen reduction catalyst electrode is an important factor affecting the development of the battery. In traditional technology, Pt shows low utilization of oxygen reduction activity due to poor contact between catalyst nanoparticles (NP), the electrolyte, and oxygen. In this work, an effective electrochemical method for the preparation of a Pt/C catalyst electrode was proposed. The carbon paper (CP) substrate was electrochemically activated by HNO3, and then, Pt nanoparticles were prepared on CP by one-step electrodeposition. Secondly, a Density Functional Theory (DFT) investigation was carried out to elucidate that the N-doped catalyst facilitates the desorption of intermediates from the catalyst surface and promotes the oxygen reduction reaction. Thirdly, the effects of acid activation voltage were discussed. The result shows that increasing the voltage significantly increases the concentration of C–N groups and decreases the particle size of Pt. The effects of acidification concentration were investigated at an optimal activation voltage of 1.6 V. When the activation concentration was 0.1 mol, Pt0 reached an optimal value, and therefore obtained an equilibrium between the adsorption of oxygen on Pt and the desorption of the intermediates. Pt/0.1CP1.6 exhibits better performance than commercial catalysts in oxygen reduction reactions. After 5000 testing cycles, the catalyst showed a constant durability with only a 3.0 mV·dec−1 increase of the Tafel slope and just a 6.7 m2·gPt−1 decline of the ECSA.