A three-dimensional in-situ self-electrolysis system based on Ni3(HITP)2/graphene-based composite aerogel particle electrodes for efficient deep removal of phenol from coking wastewater

Herein, a Ni3(HITP)2/graphene-based composite aerogel (Ni3(HITP)2/GA) particle electrode is developed for the oxidation removal of phenol with three-dimensional electrode technology. The as-constructed three-dimensional electrode system possesses high in-situ self-electrolysis capacity and achieves highly efficient degradation of phenol, completely removed within 15 min with a decomposition rate constant of 0.3283 min−1. Ni3(HITP)2 in Ni3(HITP)2/GA and the tetradentate Ni–N2O2 coordination bond generated at the composite interface produce H2O2 highly selectively via the 2e- ORR pathway. The graphene layer converts H2O2 into •OH by using the 1e- of Ni3(HITP)2 excitation and the microelectrode action of the particle electrode. Furthermore, the simultaneous generation of •OH and O2•- in the system greatly reduces the dependence on acidic environment and broadens the scope of utilization. The present work provides a new strategy for the efficient construction of particle electrodes in 3D electrode systems, which allows their potential application in the purification of coking wastewater.