Arc-discharge synthesized MWCNT/g-C 3 N 4 nanohybrids for efficient visible-light photocatalysis

Abstract A visible-light-active nanohybrid photocatalyst comprising graphitic carbon nitride (g-C 3 N 4 ) and arc-discharge produced multi-walled carbon nanotubes (MWCNTs) was synthesized via thermal polycondensation of melamine in the presence of varying MWCNT loadings (0.1–1 wt%). The structural, morphological, and optical properties of the resulting nanocomposites were comprehensively characterized using XRD, SEM, TEM, BET, PL, XPS, FTIR, and UV-DRS. The photocatalytic activity was assessed through the degradation of Rhodamine B (RhB) under visible-light irradiation. Among all compositions, the g-C 3 N 4 hybrid containing 0.1 wt % MWCNTs demonstrated the highest photocatalytic efficiency, achieving 97% degradation of RhB within 90 min, surpassing that of pristine g-C 3 N 4 (88%). The enhanced performance is attributed to improved photogenerated charge separation and prolonged carrier lifetimes facilitated by the 1D/2D heterojunction architecture, along with the favourable alignment of conduction and valence band edges. These findings highlight the synergistic effect of MWCNT incorporation in optimizing charge dynamics and broadening the visible-light utilization of g-C 3 N 4 -based photocatalysts.