Water purification of organic pollutants using photocatalytic microreactors integrating Au/TiO₂/carbon cloth under solar irradiation

Abstract

Water pollution from organic contaminants, microplastics, and cyanotoxins necessitates the development of high-efficiency and scalable purification technologies. However, conventional TiO₂-based photocatalytic systems suffer from low visible-light absorption, rapid charge recombination, and limited mass transport, reducing their practical efficiency. This study presents a novel photoelectrocatalytic (PEC) microreactor integrating Au/TiO₂ nanofibers (NFs) on carbon cloth (CC) to enhance pollutant degradation through localized surface plasmon resonance (LSPR), nonlinear electric fields, and microfluidic transport phenomena. The proposed system achieved 89 % microcystin-LR (MC-LR) degradation in 12.9 min, a reaction rate constant of 10.3 h⁻¹, which is 3 to 100 × higher than conventional TiO₂-based systems. In particular, orbitrap mass spectrometry analysis of the samples after the cyanobacterial degradation experiment confirmed that the toxic compound MC-LR was markedly removed under 1 Sun + 3 V conditions for 5 h, and that the intermediate degradation products of MC-LR were also significantly reduced compared to the control. These enhancements stem from efficient visible-light absorbance, accelerates charge separation, and promotes ion and reactant transport. The scalable modular design enables practical deployment, as validated by outdoor experiments under natural sunlight. This work introduces a high-performance PEC microreactor platform with significant potential for large-scale sustainable wastewater treatment.