[2008年10月16日]

 

最近,我组光催化分解硫化氢研究工作取得最新进展(Guijun Ma, Hongjian Yan, Jingying Shi, Xu Zong, Zhibing Lei, Can Li, 2008, Journal of Catalysis , Full paper, http://dx.doi.org/10.1016/j.jcat.2008.09.017 )。

利用光催化技术分解H2S制氢不仅可以回收H2S中的氢,而且可以利用丰富、廉价、清洁的太阳能资源,实现将太阳能转化为氢能的目标。在以往的光催化分解H2S的研究中,大多采用间接的方法来制取氢气,即将H2S溶于NaOH等碱性水溶液中,生成的硫离子(S2-HS-)作为牺牲试剂,在光催化剂及光照的作用下,水溶液中的质子(H+)被还原产生氢气。由于水溶液中单一硫离子作为牺牲试剂时光催化产氢反应的稳定性比较低,往往加入另一种阴离子(如SO32-, H2PO2-, S2O32-)与硫离子共同作为牺牲试剂,以维持稳定的光催化产氢活性,在光催化产氢过程当中,硫离子最终被氧化为各种硫的含氧酸盐副产物,无法得到单质硫。该工作采用无水的二乙醇胺(DEA)H2S的吸收剂及光催化反应溶液,以M/CdS作为光催化剂,实现了可见光及室温条件下即可将H2S完全分解为H2S的目标,在波长为420 nm处的量子效率达到30%。

AbstractThe conversion of H2S into H2 and S (H2S → H2 + S) is beneficial for both environment and energy. Here we report that H2S can be splitted stoichiometrically into hydrogen and sulfur on CdS-based photocatalysts under visible light irradiation using ethanolamine as H2S solvent and reaction media at room temperature. Raman spectra show that the produced sulfur exists as S42- and S62- after photocatalytic reaction. The hydroxyls of the reaction media are found to be crucial for the hydrogen production and the rate determination step (RDS) of photocatalytic splitting H2S in diethanolamine is discussed. Electrochemical evaluation shows that the potential of H2S splitting in ethanolamine is greatly lowered and the photo-generated electrons could be fully used to reduce protons for hydrogen production. A free radical related one-electron electrochemical oxidation process on platinum electrode is suggested. This work demonstrates the possibility for the direct splitting H2S into S and H2 via photocatalysis.

KeywordsCadmium sulfide; Ethanolamine; Polysulfide; Hydrogen production; Hydrogen sulfide conversion; Photocatalysis; Electrochemistry