ZnCr2S4: Highly effective photocatalyst converting nitrate into N2 without over-reduction under both UV and pure visible light.

ABSTRACT: 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 (??>?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.

SUBMITTER: Yue M 

PROVIDER: S-EPMC4971535 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature