Harnessing reactive hydrogen species via H2O2 photolysis for reduction of CO2 to CH3OH using CaIn2S4@ZnMOF photocatalyst

Abstract

Efficiently addressing the challenges related to the 6 H+/6e− photoreduction of CO2 into CH3OH is paramount. These challenges primarily arise from severe recombination of photogenerated carriers, reoxidation of CH3OH at high temperatures, and catalyst photo corrosion. The current study focuses on developing Zn-BTC MOF and its composites with CaIn2S4 (referred to as ZMCIS) at various concentrations of CaIn2S4 on ZnMOF (ZMCIS1, ZMCIS2, ZMCIS3, ZMCIS4, and ZMCIS5) to achieve a highly efficient and robust photocatalytic CO2 reduction to CH3OH under ambient conditions, utilizing H2O2 as the hydrogen source. Among all the composites, ZMCIS4 demonstrates excellent light absorption properties, efficient charge carrier separation, and CH3OH evolution of 49100 µmol/g.cat, with a quantum efficiency of approximately 78.41%. These values are five times higher than those observed with the pristine Zn-MOF counterpart and nine times higher than traditional CO2/H2O systems. Notably, these improved performances are attributed to the enhancement of nascent hydrogen atoms (H•) produced through the photo-splitting of H2O2 on the ZMCIS surface. The production of H• is confirmed by subjecting H• to the hydrogenation of nitrobenzene and nitrophenol, resulting in the formation of aniline and aminophenol, respectively. This study opens up a new direction for the efficient photoreduction of CO2 to CH3OH.