Highly efficient and stable photocatalytic CO2 and H2O reduction into methanol at lower temperatures through an elaborate gas–liquid–solid interfacial system

Abstract

It is extraordinarily exigent to solve the efficiency of 6H⁺/6e⁻ photoreduction of CO₂ and H₂O into methanol as the major product, which is limited by the severe photogenerated carrier recombination, the reoxidation of methanol at high temperature, and photocorrosion of catalysts. Herein, we developed an elaborate gas–liquid–solid system assembled by using a novel multicomponent SrTiO₃ (La Cr)/Cu@Ni/SiO₂/TiN (STO/Cu@Ni/SiO₂/TiN) heterojunction, realizing a highly efficient and robust photocatalytic CO₂ reduction to methanol at low temperature. STO/Cu@Ni/SiO₂/TiN exhibits excellent light absorption and high charge carriers separation nature, and the evolution of methanol is 25.8 μmol (h g_cat.)⁻¹ roughly not only 173 folds higher than those observed compared with the STO counterpart, but also is 50 times that those of traditional gas–solid two-phase system. Of note, these improved performances are attributed to the enhancement of the local surface plasmonic resonance of Cu@Ni nanoparticles by changing the local medium dielectric constant and prolonged carrier's lifetime originating from heterostructure. Moreover, plasmonic TiN nanoparticles play an important role in remaining the triphase interfacial system temperature at 90 °C and increasing methanol production excellently. While, the ionic liquid in the gas–liquid–solid system can activate CO₂ molecules, thereby greatly improves the yield of methanol. In situ Fourier transform infrared (FTIR) spectra and ¹³C isotope labeling tests reveal the reaction path of CO₂ on the photocatalyst surface. This work may provide a new direction for the efficient photoreduction of CO₂ to methanol.