Study On Photoelectrocatalytic Synthesis Of Ammonia By Titanium Dioxide And Its Composite Electrode Materials

Ammonia is one of the energy sources that human beings depend on for survival.It is widely used in chemical industry,medicine and other fields.It is considered as a promising hydrogen carrier due to its convenient transportation and storage.In the past hundred years,the Harber-Bosch synthesis ammonia process has consumed a lot of energy,leading to a worsening global warming crisis.Therefore,reducing energy consumption is a major subject facing all mankind.At present,the development of low energy consumption and low carbon emissions of photoelectrocatalytic synthesis of ammonia technology and high efficiency catalyst has become challenges.This paper adopts photoelectrocatalytic technology.An efficient catalyst was designed to promote the adsorption and activation of N₂,and a anode and cathode system was constructed to promote the NRR reaction.The main contents and results are as follows:1.Bimetallicβ-FeMoO₄ and rutile TiO₂ were prepared by solvothermal method and calcination method respectively.The photoelectrocatalytic synthesis of ammonia（PEC NRR）was constructed by electrocathode（β-FeMoO₄）and photoanode（TiO₂）.The reaction applied the potential bias of-0.5 V vs RHE toβ-FeMoO₄ cathode.And xenon lamp is used to simulate sunlight irradiation of TiO₂.Tests showed that the synthesis rate of NH₃ reached 0.41μmol h^-1 cm^-2,and the Faraday efficiency reached7.15%at-0.2 V.TiO₂ photoanode provided stable photogenerated electrons forβ-FeMoO₄ electrocathode side,andβ-FeMoO₄ bimetallic catalyst can also effectively adsorb and activate N₂.2.Photoelectrocatalysis effectively promoted NRR reaction by simulating natural light and applying bias.In this chapter,TiO₂/Co₃O₄ p-n heterojunction materials were prepared by solvothermal method and calcination method.The reaction applied the potential bias of-0.5 V vs RHE on TiO₂/Co₃O₄ catalyst,resulting in the synthesis of NH₃ at a rate of 0.531μmol h^-1 cm^-2 and Faraday efficiency of 61.49%.Tests showed that the TiO₂ and Co₃O₄ components form a close interface and internal electric field.TiO₂/Co₃O₄ p-n heterojunction enhanced photogenic electron reduction and photogenic hole oxidation.At the same time,TiO₂/Co₃O₄ p-n heterojunction enhanced charge separation and expanded light absorption range,showing excellent PEC NRR performance.3.TiO₂/Cu O composite catalyst was prepared by solvothermal method and step current method,TiO₂/Cu O-1,TiO₂/Cu O-2 and TiO₂/Cu O-3 were obtained by changing the deposition times.The reaction applied a potential bias of-0.5 V vs RHE to TiO₂/Cu O-1 catalyst.The synthesis rate of NH₃ reached 0.537μmol h^-1 cm^-2,and the Faraday efficiency reached 22.8%.Tests showed that TiO₂/Cu O-1 catalyst has better NRR performance.The catalyst showed excellent conductivity and reduced charge transfer resistance.