Preparation Of Cu And Ti Doped SiO₂ Aerogels And Their Photocatalytic Performance

Fossil energy crisis and environmental pollution have been hot issues in society today.For this reason,scientists have continuously studied sustainable renewable energy and clean fuel for several years.Hydrogen energy has always been the first choice for clean energy,which has the advantages of extremely high burning value without harmful products.However,the extremely high cost of hydrogen energy production is one of the obstacles preventing its large-scale application.Therefore,a new low-cost production method is urgent.Photolysis of hydrogen from water has become a subject of great research prospects.Solar energy is a kind of inexhaustible clean energy,and the solar water splitting to generate hydrogen is meaningful.TiO₂ has always been a popular material in photocatalysis.It has excellent photocatalytic ability,widespread presence in the earth's crust,non-toxicity,and stability in strong acids and alkalis.However,due to its large band gap,only about 5%of ultraviolet light in sunlight can be used.And its recombination efficiency of electrons and holes is high,both of which greatly limit the photocatalytic ability of TiO₂.In recent years,many studies have shown that the recombination of semiconductors can effectively reduce the recombination rate of carriers,improving the hydrogen production efficiency of the catalyst,and reduce the semiconductor band gap,extending the light absorption range of the catalyst.Therefore,we doped Cu into TiO₂ by sol-gel method,and found that Cu-doped TiO₂ with different morphologies had significant differences in catalytic efficiency and reaction process.Compared with ordinary Cu-doped TiO₂,the sample with special structure showed a band gap of about 2.5 eV and a hydrogen production rate of 16.25mmol g^-1h^-1,which was about 100 times that of pure TiO₂.Through various characterization methods,it was found that the sample had high dispersibility and rich oxygen vacancies.During the catalysis process,CuO would be reduced by photo-generated electrons to Cu₂O,which brought extraordinary catalytic ability.In addition,SiO₂ aerogels with different densities were obtained by water solvent atmospheric pressure drying and ethanol supercritical drying,respectively.SiO₂ aerogel is a good catalyst carrier with high porosity,large specific surface area and chemical inactivity.The Cu-TiO₂ nanoparticles were loaded into SiO₂ aerogel to obtain a composite aerogel with good dispersibility,and showed excellent photocatalytic ability.