Unveiling the kinetic predominance of fluoride electrosorption at S-modified defect-rich interface: Microscale disordered reconstruction induced accessible synergistic platform

[Display omitted] •BiMCS-P achieves an efficient removal capacity of 60.23 mgF− gelectrode−1.•Reconstructed mesoporous structure adjusts the electrochemical behavior.•Insufficient sulfidation creates topological and intrinsic defects.•Sulfur-modified interface induces synergistic platform for defluoridation.•Good capacity retention rate in weakly acidic solutions. Excessive hazardous fluoride (F−) have necessitated the advancement of fluoride removal electrode materials to mitigate their environmental impact. Herein, a sulfur-modified Bi-containing mesoporous synergistic platform encapsulated in a carbon shell (BiMCS-P) that provides an open nanostructured framework and high-density defects is reported. The BiMCS-P electrode removes fluoride by electrical double layer (EDL) capacitance and additional reversible redox reactions. Due to the diminished reliance of sluggish diffusion and the reduction of activation energy barrier after appropriate sulfidation, the fluoride can be further captured, as verified with high removal capacity (60.23 mg g−1 at an initial pH of 7) when processed in a 100 mg L−1F− solution, efficient energy utilization (72.8 %), and good applicability (about 80 % capacity retention at weakly acid solution). The BiMCS-P electrode can reduce the fluoride concentration from 5 mg L−1 and 2.5 mg L−1 to below the existing regulatory standards (1.5 mg L−1). The intrinsic defects optimize the electron distribution in an unsaturated coordination environment. The topological defects created during the disordered crystallographic conversion from Bi to Bi2S3 reduce the energy barrier of faradaic conversion and improves the redox activity. Moreover, the unique mesoporous framework achieves more defluoridation sites on the electrode’s surface and enables rapid ion storage behavior dominated by capacitive-controlled process at the solid–liquid interface. This study demonstrates a new strategy to improve the electrosorption performance, offering a promising advancement of defluoridation, particularly for materials that exhibit purely capacitive or purely Faradaic electrochemical characteristics.