Molecular sieve-mediated indium oxide catalysts for enhancing photocatalytic CO2 hydrogenation

In the realm of photocatalytic CO₂ hydrogenation, the adsorption-desorption behaviors and dynamics of photogenerated carriers are pivotal determinants of the kinetic processes and overall efficiency of photocatalytic reactions. Herein, 5A molecular sieve-functionalized In₂O₃ composites (denoted as IO@5A-xwt%) were fabricated through a facile impregnation-calcination method. Among them, the IO@5A-5wt% composite, with the optimized loading amount of 5A molecular sieves, showcases outstanding performance in photocatalytic conversion of CO₂ to CO, achieving a CO production rate of 2610.55 μmol g⁻¹ h⁻¹, which is 19 times higher than that of pristine In₂O₃. Moreover, the IO@5A-5wt% composite maintains acceptable catalytic stability after a prolonged experiment lasting 45 h and total of 108 cycles. A comprehensive series of characterization techniques and performance evaluations reveal that the incorporation of 5A molecular sieves significantly modulates the adsorption-desorption behavior and hole dynamics during photocatalytic reactions. The multi-channel architecture of 5A molecular sieves, featuring suitable pore sizes, effectively enhances CO₂ adsorption. Meanwhile, the surface hydroxyl groups of 5A molecular sieves facilitate the transfer of photogenerated holes, thereby suppressing the recombination of photogenerated carriers. Additionally, the reaction product H₂O desorbs more readily from the catalyst surface. These synergistic effects collectively constitute the key mechanism underlying the enhanced photocatalytic performance of the IO@5A-5wt% composite.