Synchronous reduction-oxidation of 2,4,6-tribromophenol using bifunctional AgPd@CDs in a three dimensional electrochemical reactor

[Display omitted] •AgPd@CDs were prepared as bifunctional suspended catalyst in 3DER system.•Tribromophenol abatement, toxicity and energy consumption were studied.•Catalytic activity of Pd sites was enhanced by Ag-Pd alloying effect.•Synchronous reduction-oxidation was realized due to specific properties of CDs.•Tribromophenol abatement mechanism in 3DER with AgPd@CDs was proposed. Seeking bifunctional suspended catalyst for halogenated organics dehalogenation and mineralization is urgent. Herein, a novel suspended catalyst, AgPd nanoparticles supported on cyclodextrin polymers (AgPd@CDs), was designed for synchronous reduction-oxidation of 2,4,6-tribromophenol in a three-dimensional electrochemical reactor (3DER). In this 3DER, AgPd@CDs presented 100.0% 2,4,6-tribromophenol removal efficiency under the optimized condition. The superior catalytic activity of AgPd@CDs was due to monodispersion of AgPd nanoparticles on CDs matrix and electron density modulation for Pd hollow sites' activity via electron transfer from Ag to Pd. Scavenger experiments and EPR results revealed that •OH and H• were responsible for synchronous 2,4,6-tribromophenol abatement. Moreover, CDs matrix not only promoted interfacial affinity between 2,4,6-tribromophenol and catalyst, but also inhibited reduction of O2 by H2 due to hydrophilic surface property and confined space effect in cavity, thus facilitating 2,4,6-tribromophenol enrichment and synchronous oxidation-reduction on AgPd@CDs. These findings provide conceptual insights into catalyst design for advanced wastewater treatment.