摘要
The construction of heterojunction photocatalysts for efficiently utilizing solar energy has attracted considerable attention to solve the energy crisis and reduce environmental pollution.In this study,we use the energy released from an easily-occurred exothermic chemical reaction to serve as the drive force to trigger the formation of Cd S and C_(3)N_(4) nanocomposites which are successfully fabricated with cadmium nitrate and thiourea without addition of any solvents and protection of inert gas at initial temperature,a little higher than the melting point of thiourea.The as-prepared Cd S/C_(3)N_(4) materials exhibit high efficiency for photocatalytic hydrogen evolution reaction(HER)with the HER rate as high as 15,866μmol/(g·hr)under visible light irradiation(λ>420 nm),which is 89 and 9 times those of pristine C_(3)N_(4) and Cd S,respectively.Also,the apparent quantum efficiency(AQE)of Cd S/C_(3)N_(4)–1:2–200–2(Cd S/C_(3)N_(4)–1:2–200–2 means the ratio of Cd to S is 1:2 and the reaction temperature is set at 200℃ for two hours)reaches 3.25%atλ=420±15 nm.After irradiated for more than 24 hr,the HER efficiencies of Cd S/C_(3)N_(4) do not exhibit any attenuation.The DFT calculation suggests that the charge difference causes an internal electric field from C_(3)N_(4) pointing to Cd S,which can more effectively promote the transfer of photogenerated electrons from Cd S to C_(3)N_(4).Therefore,most HER should occur on C_(3)N_(4) surface where photogenerated electrons accumulate,which largely protects Cd S from photo-corrosion.
基金
supported by National Key Research and Development Program of China(No.2016YFA0203100)
the National Natural Science Foundation of China(Nos.21537004,21777169,and 21621064)
the Beijing Municipal Natural Science Foundation(No.8202046)。
