Study On Catalytic Reduction Of CO₂ By Surface Modified Nanocrystalline Semiconductor

Under the international demand of"carbon peak and carbon neutral",the transformation and utilization of CO₂is particularly important.The conditions of photocatalytic reduction of CO₂are mild and have huge research space.In order to improve the efficiency and selectivity,high efficiency photocatalyst for CO₂conversion was designed and prepared by constructing semiconductor heterojunction,loading metal nanoparticles and introducing alkali metal ions to modify the semiconductor surface.Ui O-66 was prepared by in-situ hydrothermal synthesis on CuO surface,and Ag nanoparticles were loaded by photoreduction method.The CuO and Ui O-66 formed heterojunction and Ag nanoparticles can improve selectivity to HCOOH.The optimal ratio catalyst reduced CO₂to HCOOH at the rate of 63.00μmol·g^-1·h^-1,and the selectivity of HCOOH reached 94.91%.Through theoretical calculation,it is proved that CuO is the main active site for HCOOH generation.Ag nanoparticles have strong adsorption capacity for*H,which is favorable for the adsorption of*H and the adjacent adsorption of*OCO on CuO to form*OCOH,desorption of HCOOH molecule.The supported Cu nanoparticles were photoreduced on the surface of Ti O₂as the active site,and the Na⁺was introduced on the surface of Cu/Ti O₂as a co-catalyst by mechanical grinding method.The final catalyst was Cu nanoparticles dispersed on the homogeneous spherical Ti O₂surface,and Na⁺existed in the form of Na NO₃before the photoreduction of CO₂.Na⁺can improve the adsorption performance of the catalyst for CO₂,and the Ti-O-Cu-Na interaction between Na⁺and Cu/Ti O₂is more conducive to the activation and reduction of CO₂adsorbed on Cu.The photocatalytic reduction efficiency of CO₂to CH₃OH can reach 846.50μmol·g^-1·h^-1,which regulates catalysts loaded with0.5 wt.%Cu nanoparticles by 5 wt.%promoter Na⁺.It is 17.6 times and 1.56 times of Ti O₂and Cu（0.5%）/Ti O₂without Na⁺additives.The presence of Na⁺contributes to the stable dispersion of Cu nanoparticles.After Cu（0.5%）/Ti O₂reaction with 5 wt.%Na⁺,the dispersion of Cu on Ti O₂surface still reaches 0.667.Figure 47;Table 9;Reference 124...