single iron atom doping on BiWO monolayers triggers efficient photo-fenton reaction.

Developing an efficient photocatalytic system for hydrogen peroxide (HO) activation in Fenton-like processes holds significant promise for advancing water purification technologies. However, challenges such as high carrier recombination rates, limited active sites, and suboptimal HO activation efficiency impede optimal performance. Here we show that single-iron-atom dispersed BiWO monolayers (SIAD-BWOM), designed through a facile hydrothermal approach, can offer abundant active sites for HO activation. The SIAD-BWOM catalyst demonstrates superior photo-Fenton degradation capabilities, particularly for the persistent pesticide dinotefuran (DNF), showcasing its potential in addressing recalcitrant organic pollutants. We reveal that the incorporation of iron atoms in place of tungsten within the electron-rich [WO] layers significantly facilitates electron transfer processes and boosts the Fe(II)/Fe(III) cycle efficiency. Complementary experimental investigations and theoretical analyses further elucidate how the atomically dispersed iron induces lattice strain in the BiWO monolayer, thereby modulating the d-band center of iron to improve HO adsorption and activation. Our research provides a practical framework for developing advanced photo-Fenton catalysts, which can be used to treat emerging and refractory organic pollutants more effectively.