Yue Mufei, Wang Rong, Cheng Nana, Cong Rihong, Gao Wenliang, Yang Tao
College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
Sci Rep. 2016 Aug 3;6:30992. doi: 10.1038/srep30992.
We propose several superiorities of applying some particular metal sulfides to the photocatalytic nitrate reduction in aqueous solution, including the high density of photogenerated excitons, high N2 selectivity (without over-reduction to ammonia). Indeed, ZnCr2S4 behaved as a highly efficient photocatalyst, and with the assistance of 1 wt% cocatalysts (RuOx, Ag, Au, Pd, or Pt), the efficiency was greatly improved. The simultaneous loading of Pt and Pd led to a synergistic effect. It offered the highest nitrate conversion rate of ~45 mg N/h together with the N2 selectivity of ~89%. Such a high activity remained steady after 5 cycles. The optimal apparent quantum yield at 380 nm was 15.46%. More importantly, with the assistance of the surface plasma resonance effect of Au, the visible light activity achieved 1.352 mg N/h under full arc Xe-lamp, and 0.452 mg N/h under pure visible light (λ > 400 nm). Comparing to the previous achievements in photocatalytic nitrate removal, our work on ZnCr2S4 eliminates the over-reduction problem, and possesses an extremely high and steady activity under UV-light, as well as a decent conversion rate under pure visible light.
我们提出了将某些特定金属硫化物应用于水溶液中光催化硝酸盐还原的几个优势，包括光生激子密度高、N2选择性高（不会过度还原为氨）。实际上，ZnCr2S4表现为一种高效的光催化剂，在1 wt%助催化剂（RuOx、Ag、Au、Pd或Pt）的辅助下，效率得到了极大提高。Pt和Pd的同时负载产生了协同效应。它提供了最高的硝酸盐转化率，约为45 mg N/h，同时N2选择性约为89%。经过5个循环后，这种高活性仍保持稳定。在380 nm处的最佳表观量子产率为15.46%。更重要的是，在Au的表面等离子体共振效应的辅助下，在全弧Xe灯照射下可见光活性达到1.352 mg N/h，在纯可见光（λ > 400 nm）下为0.452 mg N/h。与之前光催化硝酸盐去除的成果相比，我们关于ZnCr2S4的工作消除了过度还原问题，在紫外光下具有极高且稳定的活性，在纯可见光下也有不错的转化率。
