Effects of organic ligands and photoactive substances on MOFs-derived Co3O4@MnOx hollow-sphere structure for efficient energy transfer and photothermocatalysis of acetone and NO

Abstract

A set of MOFs-derived Co₃O₄@MnO_x hollow-sphere were synthesized to develop a catalyst for the photothermal catalytic removal of NO using acetone as a reducing agent. The study systematically investigated the impact of organic ligands and photoactive substances on energy transfer and photothermocatalytic reactions involving acetone and NO under 5 vol % H₂O with the catalysts. At 240°C, sample C-5/1 (with an organic ligand added and Co/Mn molar ratio of 5/1) demonstrated 75 % NO conversion and 65 % acetone conversion. The highest catalytic performance was observed in the L-Py sample (with photoactive substance was added), achieving 80 % NO and 69 % acetone conversion at 240°C. The catalyst demonstrated low crystallinity, and the introduction structural defects through ligands adjusted the ratio of active components. Meanwhile, enhanced catalytic performance was attributed to light energy scattering in the inner space of microspheres, resulting in the efficient transfer of 2.17 eV energy with the addition of two photoactive substances. The elevated concentration of surface-active oxygen facilitated oxidation, while Mⁿ/Mⁿ⁺¹ (Mn³⁺/Mn⁴⁺ and Co²⁺/Co³⁺) redox cycling supplied surface oxygen in the photothermal low-temperature response. The proposed mechanism for the simultaneous degradation of acetone and NO was elucidated using Density Functional Theory calculations.