The in situ investigation of the polyaniline-derived N-doped carbon with the interdigitated array electrodes towards the oxygen reduction reaction

Nowadays, tremendous effort has been made in searching clean, high-efficient and sustainable energy, and related energy conversion methods. Oxygen reduction reaction (ORR), as one of the fundamental reactions for energy utilization, has drawn a lot of attention. Understanding the reaction process and exploring the active sites are extremely important for designing new catalysts and improving the catalytic ability. In this paper, the interdigitated array (IDA) electrodes, which show high collection efficiency and sensitivity, are proposed to explore the catalytic ability and the reaction process. With this special tool, the in situ preparation of nitrogen-doped carbon (N/C) has been realized with the pyrolysis of polyaniline (PANI) on the IDA electrodes directly. Two things should be noticed: First, this method can be used as a simple way to obtain the N/C and be used as a potential substitution catalyst for the noble metal towards the ORR for its low cost and relatively high activity; Second, the in situ preparation of catalyst on the electrode surface largely eliminated the possible electron transfer barrier between the catalyst and the electrode surface, and the high collection efficiency of the IDA electrodes ensures the detection of species with low concentration or short lifetime, therefore, the sensitivity of detection is largely improved. It demonstrates that the polyaniline-derived N/C was successfully synthesized on the micron-sized electrode surface with precise control of boundaries. The electron transfer number and corresponding percentage yield of H2O2 were detected and calculated in real time. The catalyst prepared with 700 °C shows the highest electron transfer numbers in the reaction process and the lowest percentage yield of H2O2. The content of the pyridinic nitrogen may play a crucial role in catalyzing the ORR. The idea of in situ synthetization and investigation of reaction process with IDA electrodes can be applied to study other catalytic reactions and explore the catalytic reaction process as well.