In situ construction of Fe substituted palygorskite/FeS2 heterostructure for full-spectrum photocatalytic nitrogen fixation

•Cost-effective photocatalyst constructed by 1-D natural palygorskite.•Fe substitution reduced the band gap of Pal with structure unchanged.•In situ precipitated FeS2 harvested the near infrared light.•Sulfur vacancies and Fe species contributed to activation of nitrogen.•Z-scheme FeS2/Fe-Pal preserved high charge potential for N2 reduction. The innovation of cost-effective ammonia synthesis under mild condition to replace traditional Haber-Bosch process remains a grand challenge. In this work, partial cations in one-dimensional clay palygorskite (Pal) were substituted by Fe ions to achieve lattice reconstruction, followed by in situ precipitation of FeS2 nanoparticles using a microwave hydrothermal method. The band gap of Fe-modified Pal was largely reduced with the perseverance of its original crystal structure. As the Fe content exceeded 20 wt%, excess Fe ions on the surface of Fe-Pal reacted with sulfide ions to form iron sulfide (FeS2), which owned narrow bandgap (1.3 eV) responsive in near infrared (NIR) light. The presence of abundant sulfur vacancies (Sv) as well as Fe species served as nitrogen adsorption and activation center, which promoted the adsorption of N2 and weakened the NN triple bond. A Z-scheme heterostructure can be formed between Fe-Pal and FeS2 intermediated by Sv, improving the adsorption range of solar light and enhancing the redox potential for N2 reduction. The optimized 40 wt% Fe-Pal exhibited remarkable N2 fixation ability in a wide spectrum, providing a new perspective for cost-effective photocatalytic nitrogen fixation.