Engineering a V2O5 on interstitial strategy of MWCNT/g-C3N4 staggered heterojunction for synergistic photocatalytic degradation of organic pollutants, electrocatalytic hydrogen evolution, and antimicrobial applications

Photocatalytic degradation of harmful dye pollutants and electrochemical hydrogen generation via water splitting show strong in addressing environmental pollution and energy scarcity. In this study, a V 2 O 5 (VO) interstitially modified g-C 3 N 4 /MWCNT Z-scheme heterostructure (VMG) was synthesized using an ultrasonication assisted wet impregnation method. The resulting photocatalyst was utilized for the degradation of mixed dyes (Rhodamine B (RhB) & Methylene blue (MB) in aqueous solution. The VMG nanocomposite, exhibited outstanding photocatalytic performance, achieving 92.0% degradation of MB and 88.0% degradation of RhB within 100 min under visible-light irradiation. The degradation efficiency remained above 87.0% and 83.0% against MB and RhB, respectively after five consecutive cycles. The XRD and SEM analyses post-reaction showed no significant structural or microstructural changes, confirming the excellent stability of the photocatalyst. Radical trapping experiments identified superoxide radicals as the dominant active species. From XPS/UPS analysis, the work functions were estimated and the Z-scheme charge transfer pathway was proposed to explain the enhanced photocatalytic activity in alignment with the proposed antibacterial mechanism. The ternary composite showed potent light-activated antibacterial activity, with complete inhibition of gram-positive M. luteus at 50 µg/mL. In addition, the electrocatalytic properties of the VMG nanocomposite were investigated for hydrogen evolution in KOH electrolyte medium. Electrochemical measurements revealed a low overpotential (71 mV), a high electrochemically active surface area (10.87 mF/cm 2 ), a low Tafel slope (140 mV/dec), and a reduced charge-transfer resistance compared to the pure VO sample. The robust interfacial interaction within the VMG heterostructure was found to significantly enhance catalytic activity and cycling stability. Overall, this work highlights the multi-functionality of the synthesized VMG nanocomposite in organic pollutant degradation, sustainable hydrogen generation, and antimicrobial applications.