The "4+1" strategy fabrication of iron single- atom catalysts with selective high- valent iron-oxo species generation

Single - atom catalysts (SACs) with atomic dispersion active sites have exhibited huge potentials in peroxymonosulfate (PMS) - based Fentonlike chemistry in water purification. However, four - N coordination metal (MN 4 ) moieties often suffer from such problems as low selectivity and narrow workable pH. How to construct SACs in a controllable strategy with optimized electronic structures is of great challenge. Herein, an innovative strategy (i.e., the "4 + 1" fabrication) was devised to precisely modulate the first - shell coordinated microenvironment of FeN 4 SAC using an additional N (SA - FeN 5 ). This leads to almost 100% selective formation of high - valent iron - oxo [Fe(IV) = O] (steady - state concentration: 2.00 x 10 -8 M) in the SA - FeN 5 /PMS system. In - depth theoretical calculations unveil that FeN 5 configuration optimizes the electron distribution of monatomic Fe sites, which thus fosters PMS adsorption and reduces the energy barrier for Fe(IV) = O generation. SA - FeN 5 was then attached to polyvinylidene difluoride membrane for a continuous flow device, showing long - term abatement of the microcontaminant. This work furnishes a general strategy for effective PMS activation and selective high - valent metal - oxo species generation by high N - coordination number regulation in SACs, which would provide guidance in the rational design of superior environmental catalysts for water purification.