posted on 2021-12-15, 01:03authored byHuihui Li, Estefanny Quispe-Cardenas, Shasha Yang, Lifeng Yin, Yang Yang
Hydrogen peroxide
(HP) production via electrochemical oxygen reduction
reaction (ORR-HP) is a critical reaction for energy storage and environmental
remediation. The onsite production of high-concentration H2O2 using gas diffusion electrodes (GDEs) fed by air is
especially attractive. However, many studies indicate that the air–GDE
combination could not produce concentrated H2O2, as the [H2O2] leveled off or even decreased
with the increasing reaction time. This study proves that the limiting
factors are not the oxygen concentration in the air but the anodic
and cathodic depletion of the as-formed H2O2. We proved that the anodic depletion could be excluded by adopting
a divided electrolytic cell. Furthermore, we demonstrated that applying
poly(tetrafluoroethylene) (PTFE) as an overcoating rather than a catalyst
binder could effectively mitigate the cathodic decomposition pathways.
Beyond that, we further developed a composite electrospun PTFE (E-PTFE)/carbon
black (CB)/GDE electrode featuring the electrospun PTFE (E-PTFE) nanofibrous
overcoating. The E-PTFE coating provides abundant triphase active
sites and excludes the cathodic depletion reaction, enabling the production
of >20 g/L H2O2 at a current efficiency of
86.6%.
Finally, we demonstrated the efficacy of the ORR-HP device in lake
water remediation. Cyanobacteria and microcystin-LR were readily removed
along with the onsite production of H2O2.