Tuning local electronic configuration of single atomic Co catalyst via oxide toward boosting Fenton-like activity for pollutant degradation

Single-atom Co catalysts are emerging as attractive materials for Fenton-like reaction. However, they still suffer from unsatisfactory activity due to the symmetrical electronic structure and strong electronegativity around CoN4 sites. Elaborately modulating the local electronic features of CoN4 sites can substantially improve Fentonlike activity, which is still challenging. Herein, a porous Co-N-C-based aerogel with rich CoN4 and evenembedded CoOx was fabricated as a platform that enabled efficient PMS activation for pollution degradation via regulating electronic configuration and architecture. This hybrid could degrade 99 % of p-nitrophenol (PNP, 40 mg/L) in 3 min with a rate constant of 8.95 x 10(-1) min(-1). Systematic studies and theoretical calculations revealed that CoN4 acted as main active sites with optimal binding energy for PMS activation, while CoOx could significantly increase PNP adsorption with absorption energy of 1.33 eV (2.56 times higher than that of CoN4). More importantly, the engineered CoOx induced electron redistribution of CoN4 sites, leading to electron-rich central Co atom and reduced electronegativity of N atom in CoN4. This optimal electronic configuration of CoN4 could accelerate PMS activation on Co sites, simultaneously CoOx could reduce the d-band center of hybrid to optimize the desorption of reactive oxygen species (ROSs)on CoN4 for boosting degradation kinetics. This work offers an effective and simple strategy to elaborately modulate the microenvironment of single-atom Co toward elevated catalytic performance by tandem effect of oxide.