Enhanced catalytic reduction of nitroaromatics by atomically dispersed cobalt catalyst via sulfur doping

Abstract

The catalytic reduction of 4-nitrophenol (4-NP) to the less toxic 4-aminophenol (4-AP) offers a promising strategy for the remediation of nitroaromatic-contaminated wastewater, yet its practical implementation requires cost-effective and highly efficient catalysts. Herein, we reported the synthesis of single-atom cobalt catalysts anchored on N-doped (Co-N-C) and S, N-codoped (Co-N-C-S) carbon matrices and systematically evaluated their catalytic performance toward 4-NP reduction. Benefiting from sulfur-induced electronic modulation, Co-N-C-S exhibited outstanding catalytic activity. It achieved complete reduction of 0.15 mM 4-NP within 20 s using an ultralow catalyst loading of only 0.05 mg, highlighting its potential for cost-effective and low-dosage wastewater treatment. The corresponding rate constant was 0.0361 s−1, which was 7.5 times higher than that of the sulfur-free Co-N-C counterpart (0.0048 s−1). This activity ranked among the highest values reported for state-of-the-art noble-metal catalysts. In addition, Co-N-C-S demonstrated excellent stability and durability across diverse real water matrices. Mechanistic investigations revealed that sulfur doping promoted electron migration toward isolated Co centers, thereby facilitating the reduction process. This work established heteroatom-mediated electronic regulation as an effective strategy for engineering highly active single-atom catalysts and provided new insights for the efficient treatment of nitroaromatic wastewater.