title: 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 (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.
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
authors.forename: Mufei
authors.initials: M
authors.lastname: Yue
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
authors.forename: Nana
authors.initials: N
authors.lastname: Cheng
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
authors.forename: Rihong
authors.initials: R
authors.lastname: Cong
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
authors.forename: Wenliang
authors.initials: W
authors.lastname: Gao
authors.affiliation: College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yang