混合熔盐法低温合成Sm2Ti2S2O5及其光催化分解水产氢

以TiO2、TiS2及Sm2O3为前驱体,分别加入LiCl-KCl与LiCl-CsCl的最低共熔混合物作为熔盐,在较低温度下成功合成了Sm2Ti2S2O5(STSO)颗粒。通过对比不同温度下所制备产物的X射线衍射图,首次表明STSO的热力学结晶温度在520℃左右,远低于之前报道的650℃的最低合成温度。扫描电子显微镜照片显示,采用2种混合熔盐制备的STSO都呈片状形貌;同一合成温度下,采用LiCl-CsCl熔盐制备的STSO的厚度小于LiCl-KCl所得产物。采用出射光波长大于420 nm的氙灯作为光源,在含有Na2S-Na2SO3空穴牺牲剂的溶液中,所制备的STSO颗粒表现出最高35μmol·h-1的光催化分解水产氢活性以及20 h以上的产氢稳定性。

Flux-Assisted Preparation of Sm2Ti2S2O5 Powder Applied to Photocatalytic H2 Production from Water

Sm2Ti2S2O5(STSO)was prepared by a flux method using TiO2,TiS2 and Sm2O3 as reactants,and eutectic of LiCl and KCl(LiCl-KCl)or LiCl and CsCl(LiCl-CsCl)as flux.By analyzing X-ray diffraction patterns of the samples synthesized at different temperatures,it was firstly demonstrated that the threshold crystallization temperature of STSO was 520℃,much lower than the value of 650℃that was reported previously as the lowest temperature for synthesizing STSO.Scanning electron microscope images showed that the synthesized STSO particles owned a platelike morphology.At the same temperature,LiCl-CsCl led to lower plate thickness than LiCl-KCl.The average photocatalytic H2 production rate showed volcano-like profile to synthesizing temperature,which was likely due to the effect of particle size and crystallinity on activity.Variation of hole sacrificial reagent showed that ascorbic acid produced much higher H2 evolution activity than Na2S-Na2SO3,triethylamine,triethanolamine and methanol.For the purpose of comparing with the literatures,Na2S-Na2SO3 was employed as sacrificial reagent in the following stability test.It was found that the as-prepared STSO exhibited stable H2 production over 20 h under visible light(Xe lamp,λ>420 nm)irradiation,and having nearly identical characterization results in XPS,XRD and TEM before and after photocatalytic reaction.