Polyaniline nanoparticles magnetically coated Ti/Sb-SnO2 electrode as a flexible and efficient electrocatalyst for boosted electrooxidation of biorefractory wastewater.

In this paper, a novel electrode named 2.5D Ti/Sb-SnO2/PANI was developed by magnetically in-situ integration of adsorbent and electrocatalyst, where the green synthetic Fe3O4/polyaniline (PANI) nanoparticles with fair adsorption capability were used as auxiliary electrodes and coated on the surface of Ti/Sb-SnO2 main electrode, to enrich the pollutants in the vicinity of anode and therefore boost the electrochemical oxidation (EO) efficiency. Since the interchangeable auxiliary electrodes can endow the anode with adjustability and versatility, the effect of auxiliary electrodes on the surface structure and electrochemical properties of 2.5D Ti/Sb-SnO2/PANI were extensively investigated. Results showed that a tiny amount of Fe3O4/PANI auxiliary electrodes changed the solid-liquid interface, brought massive less acessible active sites and kept the similar electrode impedance and same EO capability of 2D Ti/Sb-SnO2. In terms of organic elimination and solution biodegradability enhancement, 2.5D Ti/Sb-SnO2/PANI showed a boosted 30%-60% EO efficiency on two typical biorefractory targets, i.e., Acid Red G and lignosulphonate. The specific effectiveness was dependent on the loading amount of magenetic PANI nanoparticles. The operating mechanism of the assembled 2.5D Ti/Sb-SnO2/PANI electrode was further proposed based on many details, as well as a design rule for developing novel electrodes with high efficient EO performance for wastewater treatment. Moreover, the assembled 2.5D electrode was proved to have good sustainability and recyclability, which shows a great potential in the practical applications.