Fine-Tuning Electronic Structure through Phosphorus Doping and Defect Engineering for Selective 2e^– ORR

Doping heteroatoms into carbon-based materials has emerged as an effective strategy to enhance the two-electron oxygen reduction reaction (2e– ORR) for hydrogen peroxide (H2O2) electrosynthesis. However, conventional dopants, such as nitrogen and oxygen, due to their high electronegativity, tend to strongly bind *OOH intermediates, thereby hindering their desorption and limiting 2e– ORR selectivity. To overcome this limitation, phosphorus, a heteroatom with relatively low electronegativity, was introduced into defect-rich biochar to modulate the electronic structure of ORR active sites and improve 2e– ORR performance. The intrinsic porosity and abundant defect sites of biochar facilitate high-density phosphorus doping, overcoming the challenges posed by the large atomic radius of phosphorus. Phosphorus-doped biochar enhances 2e– ORR activity, achieving a maximum H2O2 yield of 52 mM h–1 under neutral conditions. Theoretical calculations further reveal that phosphorus doping optimizes the electronic distribution at active sites. Additionally, its synergistic interaction with carbon defects enhances oxygen adsorption and reduces the desorption energy of *OOH, thereby promoting H2O2 production. These findings provide valuable insights into both the experimental and theoretical design of cost-effective, high-performance catalysts for 2e– ORR and sustainable H2O2 production.