Synthesis And Electrochemical & Photocatalytic Performances Of Layered K₄Nb₆O₁₇ And Its Derivative

Layered K₄Nb₆O₁7 with its unique physical structure and chemical properties has attracted widespread attention in the field of photocatalytic and electrochemistry.when layered K₄Nb₆O₁7 was used as lithium ion battery anode material,its high redox potential?Nb⁵+/Nb⁴+>1.5 V,vs.Li+/Li?can effectively inhibit the formation of the SEI film and lithium ion plating,and the two-dimensional connected channel with a large number of adsorption sites cause material possess high specific capacity and energy density.Therefore,layered K₄Nb₆O₁7 is a kind of excellent lithium ion battery anode materials.At the same time,when the layered K₄Nb₆O₁7 was used as photocatalyst,it has excellent stability,selectivity,and catalytic activity,shows good performance in the treatment of environmental pollution,synthetic green energy,removal of industrial exhaust gas,and automotive exhaust and full water solution.,which belongs to a various of excellent photocatalytic materials.The layered K₄Nb₆O₁7 used as the precursor in this article,and the protonated layered H₄Nb₆O₁7,peroxy bond incorporated layered H₄Nb₆O₁7 and Cu₂O/K₄Nb₆O₁7 heterojunction composites was synthesized through the soft chemical method.Through the analysis of the synthetic process and reaction product characterization,we deduced the synthesis mechanism of synthetic products,and explored the layered H₄Nb₆O₁7 and peroxide Cu₂O/K₄Nb₆O₁7 heterojunction composites photocatalytic performance and the electrochemical performance of layered K₄Nb₆O₁7 and H₄Nb₆O₁7.Protonated layered H₄Nb₆O₁7 was prepared using the layered K₄Nb₆O₁7 as precursor.After the protonation of H₄Nb₆O₁7,the smaller size of the hydrogen ion as compared to potassium and the change in site symmetry allows more lithium-ion to be inserted reversibly into the structure during discharge in lithium cells than in the parent compound,which showed excellent electrochemical performance.At the same time,with the increase of heat treatment temperature,interlayer water gradually disappears,and at the heat treatment process of niobate phase transition happens,forming the niobium pentoxide and causing niobate present a tendency of increasing capacity.The heat treatment process of H₄Nb₆O₁7 causes the disappearing of interlayer water and niobite phase transforming to niobium pentoxide which makes the increasing electrochemical performance of niobite.Cu₂O/K₄Nb₆O₁7 heterojunction photocatalytic composite was sythesized by soft hydrothermal method using the layered H₄Nb₆O₁7 as precursor.By means of the synergy effect between hoster and guester,the cuprous oxide nanoparticles successfully dispersed in layered K₄Nb₆O₁7 and formed Cu₂O/K₄Nb₆O₁7 heterojunction structure compounds.The introduction of the cuprous oxide effectively improves the light response at the range of visible light by forming p-n junction with potassium niobate,and effectively improve the separation of generated electronic-hole pair,meanwhile,inhibiting the combination of electrons and holes.Peroxy bond incorporated layered H₄Nb₆O₁7 was sythesized by peroxide treatment using the layered H₄Nb₆O₁7 as precursor.H_2O2 molecules entered the interlayer of layered H₄Nb₆O₁7 and then reacted with Nb of layered H₄Nb₆O-17,forming Nb-0-0 coordination bonds.The introduction of the Nb-0-0 coordination bond can effectively adjust the band structure of layered H₄Nb₆O₁7,narrowing band gap from 3.49 eV to 2.68 eV,so that the photocatalyst has the visible light response,achieving the degradation of rhodamine B and photolysis water splitting under visible light irradiation.