Flash joule heating synthesis of zero-valent iron and carbon vacancy dual-site catalysts for efficient singlet oxygen generation and selective organic pollutants degradation.

Singlet oxygen (1O2) exhibits strong resistance to interference and high selectivity toward electron-rich pollutants, making it highly promising for practical wastewater treatment. However, it remains challenging to generate 1O2 from activated peracetic acid (PAA) selectively. Herein, a dual-site synergistic catalyst was constructed by anchoring zero-valent iron (Fe0) onto the residual carbon matrix of coal gasification slag (FJH-Fe/CGS-1600) via flash joule heating (FJH) induced transient thermal shock. Carbon vacancies act as electron traps to enhance PAA adsorption, while Fe0 efficiently activates PAA and optimize the reaction pathway spatially, thereby promoting the generation of 1O2. Consequently, the FJH-Fe/CGS-1600 achieved 95.7% degradation of bisphenol A within 60 min and demonstrated stable degradation performance across a wide pH range (5-8) and in chemical wastewater. Furthermore, it exhibited strong resistance to common anions found in chemical wastewater, high selectivity toward electron-rich pollutants, and extremely low metal leaching (< 0.1 mg L-1). Density functional theory (DFT) calculations reveal that carbon vacancies enhance the adsorption of the terminal oxygen in PAA (adsorption energy from -1.98 to -3.20 eV) and modulate the Fe 3d electronic structure. This research establishes a strategy for regulating non-radical species by utilizing joule heating to construct dual active sites, thereby providing a sustainable pathway for the co-treatment of coal-based solid waste and wastewater.