Insight into enhanced visible-light photocatalytic activity of SWCNTs/g-C3N4 nanocomposites from first principles

Single-walled carbon nanotubes (SWCNTs) modified g-C3N4 nanocomposites have attracted extensive attention due to their good photocatalytic activity for water splitting in the visible region, but the theoretical research on the enhancement mechanism is still lacking. Using first-principles hybrid density functional calculations, the potential photocatalytic enhancement mechanism of SWCNTs-modified g-C3N4 has been studied in detail. For different metal (9,0) and semiconductor (10,0) SWCNTs modified patterns, the two components are always linked by van der Waals forces without exception. Obvious structural folds in g-C3N4, large interlayer charge transfer, significantly enhanced visible light absorption, and smaller vertical bar Delta G(H*)vertical bar, these factors enhance the photocatalytic activity of SWCNTs/g-C3N4. Interestingly, (10,0) SWCNT have better coordination advantage with g-C3N4 than (9,0) SWCNT, resulting in (10,0) SWCNT/g-C3N4 nanocomposite with more visible structural folding for more stable structures, greater charge transfer, and more efficient visible light absorption spectra. Moreover, we also studied the photocatalytic performance of g-C3N4 modified by metal (6,0) and semiconductor (7,0) SWCNTs. As a result, the photocatalytic performance of the latter is significantly better than the former, which further shows that the semiconductor SWCNTs-modified g-C3N4 maybe more superior. The findings pave the way for the development of highly active g-C3N4-based photocatalysts.