Ag₃PO₄-Based Composite Materials: Controllable Synthesis And Photocatalytic Water Splitting For Oxygen Evolution

Semiconductor photocatalysis technology is recognized as one of the important means to solve environmental pollution and energy shortage.It can make full use of the light energy to decompose water to generate new energy sources such as hydrogen and oxygen,and thus has received widespread attention.At present,Ag₃PO₄,BiVO₄ and WO₃ have good oxygen production capacity in the conventional photocatalyst.We have studied the photocatalytic activity of Ag₃PO₄.It has been found through research that Ag₃PO₄ has good photocatalytic activity,especially in oxygen evolution photocatalysts.However,the fast combination of photoelectron and hole leads to the decrease of oxygen efficiency in photocatalytic decomposition of aquatic products.In order to solve this problem,we contemplate the inhibition of the recombination of electrons and holes in Ag₃PO₄ by transferring electrons.We found that the combination of Ag₃PO₄ and cocatalyst can rapidly transfer electrons,inhibit the problem of easy recombination of electrons and holes in the photocatalytic process of Ag₃PO₄ and thus greatly improve the performance of photocatalytic decomposition of water.The research plan is as follows:?1?We prepared a new cocatalyst flower-like MoSe₂ by hydrothermal synthesis,and then complexed with Ag₃PO₄ by simple chemical precipitation to obtain a two-phase Ag₃PO₄/MoSe₂composite photocatalytic material.The Ag₃PO₄/MoSe₂ composite photocatalytic material was subjected to photocatalytic decomposition of aquatic oxygen production performance and cycle stability test under the illumination of LED lamps.We then performed a series of experimental characterizations to analyze Ag₃PO₄/MoSe₂ composite photocatalytic materials.The results show that MoSe₂ combines with Ag₃PO₄ to form a Ag₃PO₄/MoSe₂ heterojunction composite.MoSe₂supported on the surface of Ag₃PO₄ can rapidly transfer electrons in silver phosphate.Thereby,the recombination of electrons and holes in the Ag₃PO₄ is effectively suppressed,and the improvement of the photocatalytic oxygen production activity of the Ag₃PO₄ is promoted.?2?We have also carried out the next step of research by constructing a double-cocatalyst solution.We prepared MoSe₂@CNT by adding treated carbon nanotubes in the process of hydrothermal synthesis of flower-like MoSe₂.The double cocatalyst is synthesized by a simple chemical precipitation method with Ag₃PO₄ to synthesize a ternary photocatalytic composite.The photocatalytic oxygen production performance test was again carried out and an appropriate amount of the ternary photocatalytic composite was found to have a better oxygen generating activity.Next,the composite materials were analyzed by XRD,SEM,XPS and other experimental characterization.It is also believed that the double cocatalyst greatly contributes to the improvement of the oxygen production activity of Ag₃PO₄.Based on the high-conductivity of CNT,a double-cocatalyst for the preparation of MoSe₂/CNT was prepared by adding treated CNT during the hydrothermal synthesis of flower-like MoSe₂.The composite material was composited with Ag₃PO₄ by simple chemical precipitation method to obtain a three-phase Ag₃PO₄/MoSe₂/CNT photocatalytic composite material.The crystal structure,morphology and element valence analysis of the composites were carried out by various experimental characterizations such as XRD,SEM and XPS.After the photocatalytic oxygen production performance test,the results show that the three-phase photocatalytic composite material uses the CNT with strong electrical conductivity as the intermediate transmission medium,and the electrons in the Ag₃PO₄ are transferred to the MoSe₂,which further accelerates the electrons.The transfer ability makes the photocatalytic oxygen production activity of Ag₃PO₄ further improved.?3?We used micro-spherical MoS₂ instead of the flower-like MoSe₂ to combine carbon nanotubes to construct a double cocatalyst to bond with Ag₃PO₄.Then,it is combined with Ag₃PO₄ to obtain a three-phase Ag₃PO₄/MoS₂/CNT photocatalytic composite material.XRD,SEM,XPS and other means were used to characterize and analyze the materials,and to decompose the oxygen production performance test.The results show that in the three-phase Ag₃PO₄/MoS₂/CNT photocatalytic composite material,the combination of micro-spherical MoS₂and CNT can effectively prevent the combination of holes and electrons in Ag₃PO₄,so that the light of Ag₃PO₄ is significantly improved.