Perovskite-type lanthanum-titanium oxynitride semiconductor photocatalyst and its preparation and application

Abstract

Take La 2 TiO 5 As a single precursor, thermal ammonolytic nitridation was performed in a high temperature ammonia atmosphere to prepare LaTiO with absorption band edges around 600 nm without defects detectable by EPR and UV‑Vis‑NIR spectroscopy 2 N semiconductor, annealed in inert atmosphere to obtain LaTiO with adjustable defect concentration 2 N, increasing LaTiO 2 N photocatalytic activity. or with La 2 Ti 2 O 7 As a single precursor, thermal ammonolysis nitridation under high temperature ammonia atmosphere to prepare LaTiO with defects 2 N semiconductor, inert atmosphere annealing treatment further increases defect concentration and improves LaTiO 2 N photocatalytic activity. In this method, La 2 TiO 5 As a precursor, it can effectively inhibit the reduction of Ti in the high-temperature nitridation process, inhibit the formation of low-valent Ti defects or impurity phases, and provide a comprehensive basis for the regulation of defect concentration; simple inert atmosphere annealing is used to form anion vacancy defects, and by changing the annealing process, anion vacancy defects are formed. The parameters can easily adjust the defect concentration to realize the optimization of photocatalytic activity.

Description

technical field [0001] The invention relates to a perovskite type lanthanum titanium nitride oxide semiconductor photocatalyst, a preparation method and application thereof. Background technique [0002] TiO 2 N is a metal oxynitride semiconductor with a perovskite crystal structure. Its forbidden band width is 2.1eV, the absorption edge reaches 600nm, and it has a wide range of visible light response (J. Phys. Chem. A 2002, 106, 6750-6753). TiO 2 As a light-absorbing active semiconductor material, N is excited by light to generate electrons and holes, which can be used to drive the oxidation of water to produce oxygen and reduce to produce H 2 and other chemical reactions (J.Phys.Chem.B 2003, 107, 791-797; J.Am.Chem.Soc., 2012, 134, 8348–8351; Chem.Sci., 2013, 4, 1120–1124; Nano Energy, 2015, 12, 775–784). It has very attractive potential applications in the application of photocatalysis, photoelectrocatalysis and other methods for absorbing and converting solar energy...

AI Technical Summary

Problems solved by technology

[0004] For La 2 TiO 5 Preparation of LaTiO as a precursor 2 The problem of the lower activity of the catalytic oxidation of N to produce oxygen in water, the present invention provides a method based on La 2 TiO 5 A method of obtaining a semiconductor catalyst as a precursor, which includes an activation step, so that La 2 TiO 5 After nitriding as a precursor, the semiconductor catalyst obtained by annealing and activating in an inert atmosphere has a remarkable effect of catalytic oxidation of water and oxygen generation, and can be compared with La 2 Ti 2 o 7 LaTiO obtained as a precursor 2 The effect of N catalyst is the same or higher, and the defect concentration can be easily adjusted by changing the annealing parameters to realize the optimization of photocatalytic activity

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