Designs,Synthesis And Properties Of Carbon Dioxide Photoreduction Catalysts Based On Porous Materials

The scarcity of fossil fuels and the greenhouse effect pose significant challenges to humanity.Photocatalytic CO₂ reduction,which involves converting CO₂ into valuable products such as CO,CH₄,HCOOH,and others using light as an energy source,holds immense promise.This process harnesses clean and renewable solar energy to generate valuable chemicals or fuels while reducing CO₂ emissions.Consequently,it has garnered substantial attention as a potential solution to address the energy crisis and the greenhouse effect.The designs and synthesis of highly efficient CO₂ reduction photocatalysts,characterized by high catalytic activity,long-term durability,excellent selectivity,and cost-effectiveness,have emerged as a critical research area.In recent years,although many catalysts have been developed in photocatalytic CO₂ reduction,catalysts that meet the needs of practical applications have yet to be developed.Porous materials,especially Metal-Organic Frameworks（MOFs）,Metal-Organic Polyhedra（MOPs）,and Porous-Organic Polymers（POPs）,exhibit remarkable designability and porosity.The design ability enables researchers to select secondary building units with catalytic capabilities,facilitating the construction of highly tailored porous structures.Moreover,their inherent porosity provides an abundance of catalytically active sites,further enhancing their potential for use in photocatalytic CO₂ reduction applications.As a result,these porous materials hold great promise for advancing photocatalytic CO₂reduction.In this paper,porous materials are the main research object,aiming at the problem of developing high-efficiency CO₂ reduction reaction catalysts;three kinds of excellent CO₂ photoreduction catalysts have been developed.Yielding the following key research findings:1.An excellent CO₂ photoreduction catalyst BTN-Re was synthesized according to the prior design.The catalyst integrates the classic small-molecule CO₂ reduction catalyst Re（bpy）（CO）₃Cl into the POPs material composed of triazine and bipyridine units.In the skeleton,a large number of Re（bpy）（CO）₃Cl functional units endow BTN-Re with superior CO₂ photoreduction ability;simultaneously,the pore structure and numerous Lewis base sites are conducive to BTN-Re adsorbing CO₂,thus benefiting its photocatalytic reaction.Moreover,as demonstrated by control experiments and photoluminescence spectroscopy,the assembly of Re（bpy）（CO）₃Cl on the skeleton improves the recyclability of BTN-Re and reduces detrimental electron-hole recombination.Under visible light,BTN-Re shows high efficiency for CO₂ into CO conversion(500.7μmol g^-1 h^-1).2.Presented the metal clusters of MOFs as catalysts for CO₂ photoreduction and systematically studied the CO₂ photoreduction activity of five Fe clusters and their comparison with the corresponding MOFs.The Fe₂Mn cluster exhibited the best catalytic activity,with an average rate of up to 140.9μmol h^-1 after six hours.The catalytic activity of MOFs was weaker than that of Fe₃ clusters in both the case of extra PS-assisted Fe₃ cluster-based MOFs and integrated PS into Fe₃ cluster-based MOFs because the structure of MOFs restricted the mass transfer process.This shows that the metal clusters of MOFs are a class of promising catalysts.At the same time,this idea of developing catalysts is helpful to the research and development of new CO₂ reduction catalysts.3.Referring to the structure of the classic photosensitizer Ru（bpy）₃Cl₂,the ligand containing Ru（bpy）₃Cl₂ unit was integrated into Zr-based MOPs containing bipyridine unit（named MOP-Ru）.The combination of Zr O clusters and carboxylic acid ligands in MOP-Ru endows it with excellent stability,while the Ru units in the framework endow it with good light-absorbing properties.The bipyridyl units contained in MOP-Ru can make it complex with Co ions to form MOP-Ru-Co,and the combined Co sites can participate in the reaction as active catalytic centers.The experimental results show that MOP-Ru-Co has excellent photocatalytic CO₂ reduction reaction activity,and the average CO production rate can reach 281.9μmol g^-1 h^-1 during the 6-hour reaction.The advantage of MOPs materials is that they can be dispersed in solvents as a single cage.Compared with the catalytic properties of Zr-based MOFs（Ui O-67-Ru-Co）containing Ru units and Co sites,MOP-Ru-Co shows more excellent catalytic activity.Mechanistic studies reveal that the Ru units in MOP-Ru-Co can absorb light and transfer the generated photo-generated electrons to Co sites,thereby realizing an efficient CO₂ reduction reaction.