A novel synthetic strategy of mesoporous Ti4O7-coated electrode for highly efficient wastewater treatment

Abstract

Suboxidized titanium, as a promising anode for electrocatalytic oxidation reactions in wastewater treatment, presents a viable pathway to solve the challenging water pollution. However, current suboxidized titanium anodes are primarily fabricated hot pressing of by suboxidized titanium powders, further hampering their application in wastewater treatment due to high costs and complex shaping processes. To overcome these limitations, this work employs the plasma electrolytic oxidation (PEO) technology to in-situ fabricate porous TiO2 coating precursors on commercial pure titanium substrates, followed by an annealing process to carefully reduce the TiO2 coatings with hydrogen gas, and finally achieving the cost-effective production of high-purity Magnéli phase Ti4O7-coated electrode. The obtained Ti4O7-coated electrodes exhibit a highly ordered granular structure, good crystallinity, wide electrochemical window, and low interfacial charge transfer resistance. Importantly, the Ti4O7-coated electrodes also offer a simple fabrication process, lower energy consumption, and reduced costs compared to advanced boron-doped diamond (BDD) and bulk Ti4O7 electrode. The electrochemical oxidation tests also demonstrate that Ti4O7-coated electrodes can achieve the complete degradation of 100 mg/L phenol within 240 minutes, exhibiting excellent catalytic activity and potential applications in wastewater treatment.