Research On Mechanical Catalytic Water Splitting To Produce Hydrogen And Carbon Dioxide Reduction Reactio

The excessive use of traditional energy sources such as petroleum fossils and fossil fuels leads to excessive CO₂ emissions,which bring great harm to humans and the environment.Green catalysis to convert natural resources（such as H₂O and CO₂）into high value-added energy（hydrogen energy and hydrocarbon fuel）has certain strategic significance for realizing artificial water cycle and the closure of carbon cycle and ensuring the supply of clean energy in the future.The main research is in the following aspects:1.Hydrogen production by water splitting is the most economical and feasible way to produce hydrogen energy.The separation efficiency of positive and negative charges is the key factor restricting the performance of water splitting for hydrogen production.Defect-rich Si C has the unique electronic structure and excellent catalytic active sites.It realizes high-efficiency water splitting for hydrogen production in the presence of sacrificial agent through mechanical catalysis.Under the optimal conditions（the amount of Si C is 0.01 g,the volume of the solution is 1 m L,and the ratio of the sacrificial agent methanol is 30 vol%）,hydrogen production amount is693.30μmol/g after 6 hours through the adjustment of experimental conditions.The experiments of five cycles show that Si C mechanical catalysis has good stability in hydrogen production.Through mechanism research,it is found that mechanical catalysis not only solves the problem of easy recombination of positive and negative charges on Si C surface,but also produces positive charges and hydroxyl radicals,which can oxidize sacrificial agent methanol which provide more proton sources.It promote the improvement of hydrogen production performance.2.CO₂ reduction and conversion into value-added chemicals is also an effective way to achieve global carbon balance.B₄C with excellent catalytic properties converts CO₂ and H₂O into methanol and hydrogen with high selectivity through mechanocatalysis.It improves the utilization efficiency of electrons,reduces the charge loss,and realizes the mutual coupling conversion of mechanical energy-electrical energy-chemical energy.The yield of methanol is improved by optimizing the experimental conditions such as the amount of B₄C and the volume of aqueous solution.Electrochemical test and liquid infrared characterization can explore the charge transfer path and product formation path in the process of CO₂ reduction.A large number of electrons and positive charges are mechanically catalyzed by B₄C,and positive charge is easily captured by H₂O to generate hydroxyl radicals and hydrogen ion.It is helpful to improve the electronic life and greatly improve the selectivity and yield of methanol.Finally,the sacrificial agent Na₂SO₃ is added under the optimal reaction conditions to solve the problem that methanol is easy to be oxidized.It further improves the generation efficiency of methanol.3.With the increasing global energy crisis and environmental problems,the development of clean energy and the reduction of atmospheric CO₂ have become two major research hotspots in recen years.The mechanical catalysis-B₄C-flexoelectric effect system is constructed:B₄C with centrosymmetric structure can form strong flexoelectric effect under the excitation of non-uniform mechanical force,it produce mutually separated polarized charges,which are used for hydrogen production by water splitting and carbon dioxide reduction reaction.When the amount of B₄C is0.02 g,the volume of aqueous solution is 5 m L,the reaction frequency is 40 Hz and the reaction time is 3 h,the catalytic performance of CO₂ is the best,and the hydrogen production reaches 2889.51μmol/g methanol amount is 80.72μmol/g,only a very small amount of methane and carbon monoxide.Through the exploration of its reaction mechanism,it is found that water molecules are easy to be oxidized by positive charge to release hydrogen ions.The characteristic advantage of hydrogen ions quickly obtaining electrons to form hydrogen is not only conducive to the water reduction reaction to produce a large amount of hydrogen,but also promote the efficiency and selectivity of methanol production in CO₂ reduction reaction.