Performance And Mechanism Research On Piezocatalytic Hydrogen Evolution Of Monoclinic Bismuth Vanadate

As an important carrier of future energy,hydrogen has attracted widespread attention due to its high calorific value,wide source,clean and pollution-free combustion products.Based on piezoelectric effect,piezocatalysis can transform mechanical energy to hydrogen energy,and has great application prospects.However,the low piezocatalytic efficiency greatly limits the wide application.To improve the piezocatalytic efficiency,the piezo-photocatalysis are advanced in this article.The following work has been carried out in this article:（1）Bismuth vanadate nanomaterials with different{010}/{110}facet ratios were prepared by hydrothermal method by changing p H value of the precursor.The results show that bismuth vanadate with a higher{110}facet ratio exhibits a higher piezocatalytic hydrogen production efficiency（0.6 mmol/g）.This is due to a fact that an stronger piezoelectric field generate along the[110]direction under ultrasonic vibration,improving charge separation efficiency.（2）Selective deposition of silver（Ag）nanoparticles on the{010}facet of bismuth vanadate catalyst results in a 44.7%increase in the piezocatalytic hydrogen production efficiency.This is due to the formation of Schottky junctions between Ag nanoparticles and bismuth vanadate,which can promote carrier separation and transfer.（3）Selective deposition of cobalt oxide（Co Ox）nanoparticles on the{110}facet of a bismuth vanadate catalyst using methanol as a hole sacrificial agent significantly improved the efficiency of hydrogen production to be 2 mmol/g.The Co Ox can enhance the hole transfer kinetics,while methanol can timely consume the generated holes,thereby enhancing charge separation.（4）Based on the coupling effect of light excitation and piezoelectric field,the piezo-photocatalytic efficiency of bismuth vanadate catalyst(0.081 min^-1)is much higher than the sum of piezocatalytic efficiency(0.013 min^-1)and photocatalytic efficiency,which is due to the synergistic effect of light excitation for increasing carrier concentration and piezoelectric potential for accelerating charge separation and transport.The research results of this article provide a new idea for the preparation of high-performance piezocatalysts,and provide a method reference for improving their performance.