Synthesis of Au nanoparticle-decorated carbon nitride nanorods with plasmon-enhanced photoabsorption and photocatalytic activity for removing various pollutants from water

Highlights: • The in-situ growth of Au nanoparticles on CN nanorods has been realized. • Au-CN exhibits a broad photoabsorption from UV to NIR with an edge at ∼790 nm. • Au-CN has stronger photocurrent (∼8.0 μA/cm²) than g-C₃N₄ (∼2.9 μA/cm²) and CN nanorods (∼4.5 μA/cm²). • Au-CN exhibits higher photocatalytic activity than g-C₃N₄ and CN nanorods for removing various pollutants from water. • The improved performances of Au-CN result from the plasmon effect of Au compared with those of CN nanorods. - Abstract: Herein we have developed Au nanoparticle-decorated carbon nitride (Au-CN) nanorods as novel and efficient photocatalysts. Au-CN with different Au/CN precursor molar ratios (0.5%, 1% and 2%) have been prepared by a solvothermal-hydrothermal two-step method, where CN nanorods have diameters of 20–30 nm and length of 0.5–1 μm while Au nanoparticle have diameter of ∼13 nm. Au-CN nanorods exhibit a broad photoabsorption from ultraviolet to near-infrared with edge at ∼790 nm, revealing an obvious red-shift compared with g-C₃N₄ bulk (∼460 nm), CN nanorods (∼715 nm). Under visible-light irradiation, 1%Au-CN nanorods exhibit the highest photocatalytic activity, and they can degrade 98.2% rhodamine B (RhB), 77.2% 4-chlorophenol (4-CP), 83.9% tetracycline (TC) and reduce 43.6% hexavalent chromium (Cr(VI)) in 120 min, higher than those by pure CN nanorods (70.3% RhB, 36.6% 4-CP, 54.6% TC, 23.1% Cr(VI)) and g-C₃N₄ bulk (31.5% RhB, 17.2% 4-CP, 36.9% TC, 11.8% Cr(VI)). Compared with CN nanorods, the obvious improvement of photocatalytic activity of 1%Au-CN nanorods should be attributed to the plasmon-enhanced photoabsorption and efficient separation of hole-electron pairs due to the introduction of Au nanoparticles.