Synergistic electrochemical oxidation and electrosorption for enhanced arsenic removal using a modified Magnéli phase Ti₄O₇@nanodiamond electrocatalyst

Herein, we present an advanced electrochemical oxidation-electrosorption system to address the persistent global challenge of arsenic contamination in aqueous environments with minimal environmental impact. Our approach integrates a suite of high-performance anode electrocatalysts including Magnéli phase Ti₄O₇@nanodiamond (ND)-ACC (activated carbon cloth), TiO₂@ND-ACC, and pristine-ND-ACC to synergistically enhance the oxidation and electrosorption efficiency of arsenic, facilitating the transformation of the highly toxic arsenite (As(III)) to the less toxic arsenate (As(V)). Among the modified anode electrocatalysts, the Magnéli phase Ti₄O₇@ND material exhibited an arsenic removal performance that was several orders of magnitude higher, significantly surpassing the pristine-ND catalyst. This outstanding performance was achieved through a combination of efficient electrochemical oxidation, adsorption, and desorption processes. The remarkable enhancement in the performance is attributed to the unique electronic structure and surface properties of Magnéli phase Ti₄O₇@ND, which facilitate superior charge transfer and stronger interactions with arsenic species. Comprehensive analysis, including repeated batch experiments, electrochemical characterizations (using CV and Mott-Schottky plots), and electronic structure calculations, provided valuable insights into the critical roles of Magnéli phase Ti₄O₇ and ND in arsenic oxidation and electrosorption, reinforcing the practical applicability of this material for the sustainable remediation of arsenic contaminated water systems.