Construction of high-entropy spinel/palygorskite nanocomposite for photocatalytic CO2 reduction coupled with biomass conversion

The conversion of carbon dioxide and water into fuels through artificial photosynthesis is of great significance for achieving carbon neutrality. However, this reaction faces great challenge due to the sluggish kinetics. Herein, high-entropy spinel (NiFeMnCoCu)₃O₄ nanoparticles supported on palygorskite (Pal) were synthesized using a facile sol-gel method, and the composite was employed for photocatalytic CO₂ reduction coupled with biomass-derived 5-hydroxymethylfurfural (HMF) oxidation. The hydrochloric acid-modified Pal (H-Pal) facilitated the generation of high concentrations of oxygen vacancies in (NiFeMnCoCu)₃O₄, inducing a localized surface plasmon resonance (LSPR) effect, expanding the light absorption range to the near-infrared region and releasing high-energy hot electrons, thereby enhancing the photocatalyst's photothermal conversion capability. The HMF oxidation along with dehydrogenation addressed the issue of slow kinetics while harnessing the potential of biomass resources. Moreover, the high concentration of oxygen vacancies significantly improved the separation efficiency of charge carriers, favoring the enhanced photocatalytic CO₂ reduction and HMF oxidation ability of the (NiFeMnCoCu)₃O₄/H-Pal composite. Current study provides a novel strategy for the conversion of CO₂ and the high-value utilization of biomass.