A General Strategy to Synthesize Fluidic Single Atom Electrodes for Selective Reactive Oxygen Species Production

Fine-tuning the geometric and electronic structure of catalytic metal centers via N-coordination engineering offers an effective design for the electrocatalytic transformation of O-2 to singlet oxygen (O-1(2)). Herein, we develop a general coordination modulation strategy to synthesize fluidic single-atom electrodes for selective electrocatalytic activation of O-2 to O-1(2). Using a single Cr atom system as an example, >98% O-1(2) selectivity can be achieved from electrocatalytic O-2 activation due to the subtle engineering of Cr-N-4 sites. Both theoretical simulations and experimental results determined that end-on adsorption of O-2 onto the Cr-N-4 sites lowers the overall activation energy barrier of O-2 and promotes the breakage of Cr-OOH bonds to form (OOH)-O-center dot intermediates. In addition, the flow-through configuration (k = 0.097 min(-1)) endowed convection-enhanced mass transport and improved charge transfer imparted by spatial confinement within the lamellar electrode structure compared to that of batch reactor (k = 0.019 min(-1)). In a practical demonstration, the Cr-N-4/ MXene electrocatalytic system exhibits a high selectivity toward electron-rich micropollutants (e.g., sulfamethoxazole, bisphenol A, and sulfadimidine). The flow-through design of the fluidic electrode achieves a synergy with the molecular microenvironment that enables selective electrocatalytic O-1(2) generation, which could be used in numerous ways, including the treatment of environmental pollution.

Automated summary

Fine-tuning the geometric and electronic structure of catalytic metal centers via N-coordination engineering allows for the selective electrocatalytic activation of O-2 to O-1(2). Through a coordination modulation strategy, fluidic single-atom electrodes are synthesized, achieving >98% selectivity towards O-1(2) generation. The use of end-on adsorption of O-2 onto Cr-N-4 sites lowers the activation energy barrier, promoting the breakage of Cr-OOH bonds and the formation of (OOH)-O-center dot intermediates. The flow-through configuration of the fluidic electrode enhances mass transport and charge transfer, resulting in improved performance compared to batch reactors.