From Algal Threat to Fe/N‐Rich Single‐Atom Catalyst: Engineering Iron‐Accumulating Algae for High‐Performance Fenton‐Like Chemistry and Lifecycle Sustainability

ABSTRACT This study presents a sustainable strategy to transform iron‐accumulating algae—an environmental nuisance—into high‐performance iron single‐atom catalysts (Fe‐SACs), enabling efficient Fenton‐like catalysis with full lifecycle sustainability. We selected 16 distinct polluting algal species, including eleven iron‐accumulating types with varying iron contents and five iron‐free species for comparison. Iron contents with a range of 0.022–1.56 wt.% could be achieved in the Fe‐SACs derived from iron‐accumulating algae using a tailored pyrolysis approach after urea treatment for increasing nitrogen content to coordinate with the iron atom. We found that the iron species after transferring into single‐atom iron could promote the catalytic activity based on the catalytic roles of fundamental compositions in these algae and urea‐derived nitrogen species. A certain correlation ( R 2 = 0.69) was observed between the iron contents in these iron‐accumulating catalysts and the resulting catalytic performances for pollutant degradation. A full lifecycle assessment (LCA) was further conducted to quantitatively evaluate the environmental benefits of this “waste‐to‐wealth” strategy compared to the conventional algae disposal method. Importantly, the principle established here—using naturally iron‐enriched biomass, such as iron‐accumulating plants grown in distinctive soils like the red soils of Southern China, or iron‐rich sewage sludge, as precursors—exhibits broad applicability for water purification.