Evolutionary trends and photothermal catalytic reduction performance of carbon dioxide by MOF-derived MnOx

Metal oxide catalysts derived from MOFs can inherit the excellent performance from their parent MOFs, possess abundant surface defects and high stability, and have attracted widespread interest in multiphase catalysis. In this study, we used Mn-MOF as a precursor and systematically investigated the evolution of MnOx catalysts by setting different calcination temperatures and times. XRD, SEM, TEM, Fourier transform infrared spectroscopy (FTIR), N2 adsorption–desorption analysis, XPS, H2-TPR, CO2-TPD, electrochemical characterization, and other methods were used to investigate the structural characteristics, microstructure, surface properties, and photoelectric properties of the catalysts. The catalytic performance of the catalysts was also investigated through photocatalytic carbon dioxide hydrogenation reduction tests. Research has shown that calcination temperature and time have a significant impact on the phase structure and surface properties of MnOx, and the physicochemical properties of derived MnOx can be controlled by controlling calcination temperature and time. Among them, MnOx-500 has a wider light absorption range, better electron transfer performance, richer oxygen vacancies, and excellent separation performance of photo generated charge carriers, resulting in higher photocatalytic CO2 hydrogenation and reduction performance. Its CO yield and selectivity reached 7420 μmol/g/h and above 99 %, respectively. This study provides valuable references for the preparation, optimization, and utilization in CO2 photothermal catalytic conversion of MnOx catalysts derived from MOFs.