Carbon vacancies enriched carbon nitride nanotubes for Pd coordination environment optimization: Highly efficient photocatalytic hydrodechlorination and CO2 cycloaddition

The use of easily available solar energy to achieve pollutants efficient degradation and waste carbon resource CO2 utilization under mild conditions is highly desired. Herein, novel carbon vacancies enriched nanotubes graphitic carbon nitride (SCNT-500) has been successfully fabricated via melamine (MA) supramolecular hydrogen-bonded self-assembly in the presence of H2SO4. Pd NPs loaded carbon vacancies enriched carbon nitride nanotubes (Pd/SCNT-500) were used for photocatalytic chlorophenols hydrodechlorination and CO2 cycloaddition with styrene oxide. Up to 6.93 s−1 4-chlorophenol hydrodechlorination TOF and obviously improved CO2 cycloaddition efficiency could be realized with Pd/SCNT-500. The improved photocatalytic efficiency should be related to the morphology and carbon vacancies based Pd coordination environment optimization. Such as, the surface area increased nanotubes structure promoted light harvesting along with photoelectrons and holes generation; the carbon vacancies improved excited electrons capture, photoinduced carriers recombination inhibition along with substrates adsorption with electron rich Pd NPs. Mechanism studies not only demonstrated the important role of atomic hydrogen and Pd coordination environment optimization in the chlorophenols hydrodechlorination, but also confirmed the promotion ability of photogenerated electrons on CO2 cycloaddition. Carbon vacancies enriched carbon nitride nanotubes has been successfully fabricated via melamine supramolecular hydrogen-bonded self-assembly in the presence of H2SO4. Up to 6.93 s−1 4-chlorophenol hydrodechlorination TOF and obviously improved CO2 cycloaddition efficiency could be realized with Pd/SCNT-500. The improved photocatalytic efficiency was related to the morphology and carbon vacancies based Pd coordination environment optimization. [Display omitted] •Carbon vacancies enriched carbon nitride nanotubes were firstly fabricated with melamine self-assembly and H2SO4 corrosion.•Up to 6.93 s−1 4-chlorophenol HDC TOF and obviously improved CO2 cycloaddition efficiency with Pd/SCNT-500.•Pd coordination environment was optimized with nanotubes morphology and carbon vacancies.•The chlorophenols reduction pathway and important role of atomic hydrogen in HDC were confirmed.•The promotion ability of photogenerated electrons on CO2 cycloaddition was verified.