Preparation And Catalytic Performance Of Micro-nano Metal Oxides Based On Amorphous Alloys

Photocatalytic degradation of organic pollutants has the characteristics of green and energy-saving,high efficiency and environmental protection.At the same time,it can completely mineralize organic pollutants into inorganic small molecular substances,and will not produce secondary pollution in the entire process.Therefore,it is a pollution treatment method with broad application prospect.At present,how to efficiently and quickly prepare a photocatalyst with strong photocatalytic performance is one of the research hotspots of experts and scholars.In this paper,TiO₂ photocatalyst materials with relatively strong catalytic properties were prepared by dealloying and hydrothermal methods using copper-based amorphous alloy as the precursor.Through the control of precursor composition and preparation process,the photocatalytic performance of the materials was improved by refining,doping and oxide recombination.The photocatalytic performance of the materials was evaluated by photocatalytic degradation of rhodamine B（Rh B）solution and methyl orange（MO）solution.The rutile phase TiO₂ nanoparticles were prepared by dealloying Cu₆₅Ti₂₅Ce₁₀ amorphous alloy under HNO₃ system.Compared with TiO₂ particles prepared by dealloying of Cu₇₀Ti₃₀amorphous alloy,the preparation time of as-fabricated TiO₂ was shortened from 96 h to 24 h.The average diameter of rutile TiO₂ particles decreased from 300 nm to 150 nm.The photocatalytic degradation of Rh B solution（10 mg/L）under ultraviolet（UV）light irradiation is 0.040 min^-1.When the Cu₇₀Ti₃₀ amorphous ribbons were dealloying in HNO₃ system to prepare rutile TiO₂,the average diameter of the as-prepared rutile TiO₂ particles can be refined to 40 nm by introducing a magnetic stirring process into the dealloying process.This is because the introduction of the magnetic stirring process can make the TiO₂ particles fall off the surface of the amorphous ribbons after reaching a certain particle size in the initial stage of formation,preventing their further growth on the surface of the ribbon.The photocatalytic performance of the as-prepared sample under UV light irradiation has been significantly improved.The photocatalytic reaction constant（UV irradiation,10 mg/L Rh B solution）is 0.034 min^-1.The degradation rate of Rh B reached 86.8%at 60 min.At the same time,under visible light,adding H₂O₂ and TiO₂ produced a photocatalytic synergistic effect.The photocatalytic performance of the sample prepared by magnetic stirring was also significantly improved.The catalytic reaction constant（visible light,10 mg/L Rh B solution）was 0.068 min^-1.After dealloying Cu₇₀Ti₃₀ amorphous alloy to prepare TiO₂ in HNO₃ system,Na₂S solution（0.1 M）was added dropwise to the dried TiO₂ to convert Cu²⁺adsorbed on the ribbon surface into Cu S nanoparticles loaded on the surface of TiO₂ particles.The loading of Cu S can improve the photocatalytic performance of the rutile by inhibiting the recombination of photogenerated electrons and holes.Cu S supported TiO₂ photocatalyst has a catalytic reaction constant（UV irradiation,10 mg/L MO solution）of 0.010 min^-1.The Cu₇₀Ti₃₀ amorphous alloy is reacted in ammonium persulfate（（NH₄）₂S₂O₈）solution to prepare S-doped anatase TiO₂.And S is doped into the crystal lattice of TiO₂ in the form of SO₄^2-,introducing a large number of lattice imperfection into TiO₂.Introducing a doping energy level into the bandgap reduces the bandgap width of anatase TiO₂ to 2.90 e V,promotes the separation of photogenerated electrons and holes,and inhibits the recombination of photogenerated electrons and holes to improve the photocatalytic performance.Through the subsequent heat treatment process,the S content of S-doped TiO₂ can be adjusted.Under UV irradiation,the optimal photocatalytic reaction constant（10 mg/L Rh B solution）can be 0.602min^-1.(Cu₇₀Ti₃₀)₉₅Ni₅ amorphous alloy ribbons were hydrothermally reacted in（NH₄）₂S₂O₈solution to obtain S-doped anatase TiO₂ photocatalyst.The addition of Ni element can realize the effective refinement of TiO₂ photocatalyst particles and increase the catalytic reaction constant of S-doped TiO₂（UV irradiation,20 mg/L Rh B solution）to 0.365 min-1,While the catalytic reaction constant of S-doped TiO₂ prepared via hydrothermal method of Cu₇₀Ti₃₀amorphous alloy is 0.221 min^-1,under the same condition.(Cu₇₀Ti₃₀)₉₅Ni₅amorphous ribbons were hydrothermally reacted in（NH₄）₂S₂O₈ solution to obtain anatase/cassiterite（TiO₂/Sn O₂）composite oxide photocatalyst.The addition of Sn element can realize the preparation of composite oxide particles,and can also refine the particle size of the TiO₂/Sn O₂ particles,and obtain microspheres of about 450 nm formed by agglomeration of nanoparticles with an average particle size of about 40 nm.TiO₂/Sn O₂ composite oxide has the best photocatalytic performance,and its photocatalytic reaction constant（UV irradiation,20 mg/L Rh B solution）is 0.456 min^-1.The photocatalytic degradation rate of Rh B solution with a concentration of 20mg/L can be achieved as high as 92.3%in 6min.The excellent photocatalytic performance of the material is the result of the interaction of S element doping and TiO₂/Sn O₂ composite oxide.