Preparation And Properties Of Narrow Band Gap Semiconductor CuWO₄

In order to alleviate energy shortage and environmental pollution,the development of clean energy is urgent.Photoelectrochemical hydrogen production via water splitting has a broad prospect.Ti O₂is widely used,but due to its’wide band gap,the utilization of sunlight is limited.Cu WO₄has suitable band gap and good chemical stability,but low electron mobility and high probability of electron-hole recombination,resulting in photocurrent is lower than theoretical value.USP was used to prepare and modify Cu WO₄photoanode films.Cu WO₄films were characterized by XRD,SEM,XPS,UV-vis and electrochemical workstation.The main contents are as follows:Cu WO₄photoanode films were prepared by USP.Results show that when reaction conditions are heat treatment temperature 550℃,deposition temperature 350℃,film depositing layer 7,and raw material ratio n（Cu）:n（W）=1:1,photocurrent density of Cu WO₄photoanode was 0.13 m A/cm²at 1.23 V vs RHE meanwhile has good stability.In order to increase the carrier concentration and therefore improve the conductivity of Cu WO₄,the influences of Sn⁴⁺and Fe³⁺doping on Cu WO₄photoelechemical properties were studied.Sn⁴⁺and Fe³⁺can increase the carrier concentration by substituting Cu²⁺as donor impurity.When 1 mol%Sn⁴⁺doped,photocurrent density reached 0.23 m A/cm²,and the carrier concentration was 8.8×10²⁰cm^-3which was twice of undoped Cu WO₄.When 0.7 mol%Fe³⁺doped,photocurrent density reached 0.27m A/cm²,and the carrier concentration was 1.65×10²¹cm^-3which was 2.7 times higher than that of undoped Cu WO₄.By constructing Cu:W compositions gradient Cu WO₄thin films and Fe³⁺gradient doped Cu WO₄film along the thickness direction,the influence of the built-in electric field on the hole-electron separation efficiency was studied.It was found that Fe³⁺gradient doped Cu WO₄film had better performance,and the photocurrent density was up to 0.35m A/cm²,which is 2.69 times of the homogeneous thin films.Figure 60;Table 4;References 66.