Carbon defect induced electron transfer promotes electrocatalytic activation of molecular oxygen to selectively generate singlet oxygen for pollutants removal

This study explored the design of heterojunctions incorporating defective graphene and boron nitride (BN) to activate molecular oxygen (O₂) and degrade sulfamethoxazole (SMX) by establishing efficient electron transport channels. These heterojunction catalysts, designed using theoretical predictions, were synthesized by controlling carbon defect concentration and pyrolysis temperature. The optimized GBN cathode achieved a maximum SMX degradation rate of 0.0252 min⁻¹, with a total organic carbon (TOC) removal efficiency of 47.31 %. Singlet oxygen (¹O₂) was identified as the primary reactive oxygen species, exhibiting a generation rate of 18.66 μM min⁻¹ and contributing 93.5 % to SMX degradation. Results demonstrated that an optimal defect concentration enhances electron transfer, promoting the 2-electron reduction of O₂ to H₂O₂ and facilitating further H₂O₂ activation, thereby accelerating SMX degradation. This work advances the development of non-metallic cathodic catalysts and provides valuable insights into electrochemical degradation mechanisms for organic pollutants. [Display omitted] •Carbon defects in metal-free heterojunctions establish electron transport channels.•Electron transfer within the heterojunction promotes transformation of O2 to 1O2.•Emerging pollutant sulfamethoxazole is efficiently removed by this electrocatalysis.•Carbon defects play key role in sustainable solutions for environmental remediation.