One-pot molten salt method for constructing CdS/C3N4 nanojunctions with highly enhanced photocatalytic performance for hydrogen evolution reaction

The construction of heterojunction photocatalysts for efficiently utilizing solar energy has attracted considerable attention to solve the energy crisis and reduce environmental pollu-tion.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 CdS and C3N4 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 melt-ing point of thiourea.The as-prepared CdS/C3N4 materials exhibit high efficiency for photo-catalytic hydrogen evolution reaction (HER) with the HER rate as high as 15,866 μmol/(g·hr)under visible light irradiation (λ ＞ 420 nm),which is 89 and 9 times those of pristine C3N4 and CdS,respectively.Also,the apparent quantum efficiency (AQE) of CdS/C3N4-1∶2-200-2(CdS/C3N4-1∶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％ at λ =420 ±415 nm.After irradiated for more than 24 hr,the HER efficiencies of CdS/C3N4 do not exhibit any attenuation.The DFT calculation sug-gests that the charge difference causes an internal electric field from C3N4 pointing to CdS,which can more effectively promote the transfer of photogenerated electrons from CdS to C3N4.Therefore,most HER should occur on C3N4 surface where photogenerated electrons accumulate,which largely protects CdS from photo-corrosion.