Efficient synthesis of H2O2 via oxygen reduction over PANI driven by kinetics regulation of carbon dots

Electrocatalytic two-electron (2e- ) oxygen reduction reaction (ORR) is a promising method to realize the sus-tainable production of H2O2. However, the 4e- pathway competes with 2e- ORR, presenting a challenge to the design of highly selective, low-cost catalysts. In addition to the design of active sites, the regulation on elec-trocatalytic kinetics is another strategy to get ideal 2e- ORR route. Here, cobalt doped carbon dots (CDs-Co) were used to regulate the electron transport kinetics on polyaniline (PANI) by constructing p-n heterojunction. The electron transfer kinetics and oxygen molecular activation process on PANI/CDs-Co were studied and analyzed using the transient photo-induced voltage (TPV) and pulse voltage-induced current (PVC) technologies, respectively. These results show that CDs-Co not only reduces the over-potential of oxygen molecular activation, but also reduces the transient electron concentration on PANI, which effectively improves the selectivity and activity of H2O2 production via ORR. The obtained PANI/CDs-Co-2 shows a H2O2 selectivity nearly 100.0% higher than that of PANI (76.3%). And it exhibits a H2O2 productivity of 3.5 mol g-cat1 h-1 at 0 V vs. RHE tested by gas diffusion electrode device. This work provides new insights for the design of 2e- ORR catalysts and the study of electrocatalytic kinetics.