High-loading As single-atom catalysts harvested from wastewater towards efficient and sustainable oxygen reduction

Abstract

Arsenic (As) is a common element in groundwater contamination with similar chemical properties to nitrogen, exhibiting potential activity towards oxygen reduction reaction (ORR). However, the practical application of recovering arsenic-containing contaminants for ORR faces the formidable challenge of a trade-off between high activity and stability. Herein, we first report universal strategies to synthesize high-loading (up to 13.78 wt%) non-metal monoatoms on carbon and prepare As monoatomic catalysts as a demonstration. The dispersed zinc ions chelated by α-D-glucose significantly increase the loading of As monoatoms. Moreover, topological defects constructed by zinc evaporation enhance the intrinsic activity of adjacent As. The catalyst exhibits a much better half-wave potential (0.901 V) than 20% Pt/C (0.856 V). Re-calcination is further proposed to overcome the poor oxidation resistance of catalysts with abundant carbon defects. The catalyst treated by re-calcination demonstrates unprecedented stability, with only 9.86% deterioration in current density after 590 hours of operation in the fuel cell, outperforming the most advanced carbon-based catalysts. Our discoveries facilitate the practical application of high-loading, high-activity and high-stability non-metal catalysts originating from pollutants.