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Solar light-driven photocatalytic hydrogen evolution over ZnIn2S4 loaded with transition-metal sulfides.

Shen S, Chen X, Ren F, Kronawitter CX, Mao SS, Guo L - Nanoscale Res Lett (2011)

Bottom Line: After loading 1.0 wt.% CuS together with 1.0 wt.% Pt on ZnIn2S4, the activity for H2 evolution was increased by up to 1.6 times, compared to the ZnIn2S4 only loaded with 1.0 wt.% Pt.Here, transition-metal sulfides such as CuS, together with Pt, acted as the dual co-catalysts for the improved photocatalytic performance.This study indicated that the application of transition-metal sulfides as effective co-catalysts opened up a new way to design and prepare high-efficiency and low-cost photocatalysts for solar-hydrogen conversion.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China. ssmao@lbl.gov.

ABSTRACT
A series of Pt-loaded MS/ZnIn2S4 (MS = transition-metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS) photocatalysts was investigated to show various photocatalytic activities depending on different transition-metal sulfides. Thereinto, CoS, NiS, or MnS-loading lowered down the photocatalytic activity of ZnIn2S4, while Ag2S, SnS, or CuS loading enhanced the photocatalytic activity. After loading 1.0 wt.% CuS together with 1.0 wt.% Pt on ZnIn2S4, the activity for H2 evolution was increased by up to 1.6 times, compared to the ZnIn2S4 only loaded with 1.0 wt.% Pt. Here, transition-metal sulfides such as CuS, together with Pt, acted as the dual co-catalysts for the improved photocatalytic performance. This study indicated that the application of transition-metal sulfides as effective co-catalysts opened up a new way to design and prepare high-efficiency and low-cost photocatalysts for solar-hydrogen conversion.

No MeSH data available.


Average rates of H2 evolution. The average rates of H2 evolution over Pt-loaded MS/ZnIn2S4 (MS = metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS) under solar light irradiation in the initial 20-h period.
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Figure 1: Average rates of H2 evolution. The average rates of H2 evolution over Pt-loaded MS/ZnIn2S4 (MS = metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS) under solar light irradiation in the initial 20-h period.

Mentions: We investigated the photocatalytic activity for hydrogen evolution over MS/ZnIn2S4 (MS = metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS). Photocatalytic activities for hydrogen evolution over MS/ZnIn2S4 were evaluated by loading 1 wt.% Pt as co-catalyst. Figure 1 shows the average rates of H2 evolution over Pt-loaded MS/ZnIn2S4 photocatalysts under simulated solar irradiation in the initial 20-h period. The Pt-ZnIn2S4 showed a photocatalytic activity for H2 production at the rate of 126.7 μmol·h-1, which is comparable to reported values in previous literatures [18-20]. The hydrogen production rates of Pt-MS/ZnIn2S4 photocatalysts varied with different kinds of loaded transition-metal sulfides. The Pt-MS/ZnIn2S4 (MS = Ag2S, SnS, and CuS) photocatalysts displayed enhanced activities for hydrogen evolution under solar irradiation. In particular, the H2 evolution rate greatly increased to 200 μmol·h-1 after loading 1.0 wt.% of CuS on ZnIn2S4. In this CuS/ZnIn2S4 sample, the formation of CuS (copper monosulfide) could be evidenced by XPS analysis results shown in Figure S5 (Additional file 1). The survey scan spectrum (Figure S5A of Additional file 1) indicated the presence of Cu, Zn, In, and S in the sample [21,31]. The binding energies shown in Figure S5E (Additional file 1) for Cu 2p3/2 and Cu 2p1/2 were 952.5 and 932.5 eV, respectively, which are close to the reported value of Cu2+[31]. The actual molar ratio of Cu:Zn:In:S was 0.011:0.2:0.39:1.01 as confirmed by XRF analysis result, with weight content of CuS calculated to be 1.15 wt.%, which is quite close to the proposed stoichiometric ratio. The photocatalytic activities for hydrogen evolution over Pt-MS/ZnIn2S4 (MS = Ag2S, SnS, and CuS) in the initial 20-h period were measured to increase in the order of SnS <Ag2S <CuS. Generally, these transition-metal sulfides (SnS, Ag2S, and CuS) alone are not photocatalytically active for H2 evolution, as no H2 was detected when they were used as the catalysts. Thus, the improvement of photocatalytic performances of Pt-MS/ZnIn2S4 (MS = Ag2S, SnS, and CuS) can be related to the enhanced separation of photo-generated electrons and holes induced by the hybridization of MS with ZnIn2S4. In this photocatalysis system, transition-metal sulfides (MS = Ag2S, SnS, and CuS) combined with noble-metal Pt acted as dual co-catalysts for photocatalytic hydrogen evolution. However, when transition-metal sulfides (MS = CoS, NiS, and MnS) were loaded on ZnIn2S4, the rates of H2 evolution over Pt-MS/ZnIn2S4 (MS = CoS, NiS, and MnS) were sharply decreased. Instead of the role as effective co-catalysts, these transition-metal sulfides (i.e., CoS, NiS, and MnS) may work as the recombination center of photo-generated electron-hole pairs, which lowered the photocatalytic activity for hydrogen evolution over Pt-MS/ZnIn2S4 (MS = CoS, NiS, and MnS). Further investigation is needed and also under way to provide enough supporting information to evidence the negative effects of CoS, NiS, and MnS, although main attention has focused on the more effective co-catalysts such as Ag2S, SnS, and CuS in the following discussion.


Solar light-driven photocatalytic hydrogen evolution over ZnIn2S4 loaded with transition-metal sulfides.

Shen S, Chen X, Ren F, Kronawitter CX, Mao SS, Guo L - Nanoscale Res Lett (2011)

Average rates of H2 evolution. The average rates of H2 evolution over Pt-loaded MS/ZnIn2S4 (MS = metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS) under solar light irradiation in the initial 20-h period.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211356&req=5

Figure 1: Average rates of H2 evolution. The average rates of H2 evolution over Pt-loaded MS/ZnIn2S4 (MS = metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS) under solar light irradiation in the initial 20-h period.
Mentions: We investigated the photocatalytic activity for hydrogen evolution over MS/ZnIn2S4 (MS = metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS). Photocatalytic activities for hydrogen evolution over MS/ZnIn2S4 were evaluated by loading 1 wt.% Pt as co-catalyst. Figure 1 shows the average rates of H2 evolution over Pt-loaded MS/ZnIn2S4 photocatalysts under simulated solar irradiation in the initial 20-h period. The Pt-ZnIn2S4 showed a photocatalytic activity for H2 production at the rate of 126.7 μmol·h-1, which is comparable to reported values in previous literatures [18-20]. The hydrogen production rates of Pt-MS/ZnIn2S4 photocatalysts varied with different kinds of loaded transition-metal sulfides. The Pt-MS/ZnIn2S4 (MS = Ag2S, SnS, and CuS) photocatalysts displayed enhanced activities for hydrogen evolution under solar irradiation. In particular, the H2 evolution rate greatly increased to 200 μmol·h-1 after loading 1.0 wt.% of CuS on ZnIn2S4. In this CuS/ZnIn2S4 sample, the formation of CuS (copper monosulfide) could be evidenced by XPS analysis results shown in Figure S5 (Additional file 1). The survey scan spectrum (Figure S5A of Additional file 1) indicated the presence of Cu, Zn, In, and S in the sample [21,31]. The binding energies shown in Figure S5E (Additional file 1) for Cu 2p3/2 and Cu 2p1/2 were 952.5 and 932.5 eV, respectively, which are close to the reported value of Cu2+[31]. The actual molar ratio of Cu:Zn:In:S was 0.011:0.2:0.39:1.01 as confirmed by XRF analysis result, with weight content of CuS calculated to be 1.15 wt.%, which is quite close to the proposed stoichiometric ratio. The photocatalytic activities for hydrogen evolution over Pt-MS/ZnIn2S4 (MS = Ag2S, SnS, and CuS) in the initial 20-h period were measured to increase in the order of SnS <Ag2S <CuS. Generally, these transition-metal sulfides (SnS, Ag2S, and CuS) alone are not photocatalytically active for H2 evolution, as no H2 was detected when they were used as the catalysts. Thus, the improvement of photocatalytic performances of Pt-MS/ZnIn2S4 (MS = Ag2S, SnS, and CuS) can be related to the enhanced separation of photo-generated electrons and holes induced by the hybridization of MS with ZnIn2S4. In this photocatalysis system, transition-metal sulfides (MS = Ag2S, SnS, and CuS) combined with noble-metal Pt acted as dual co-catalysts for photocatalytic hydrogen evolution. However, when transition-metal sulfides (MS = CoS, NiS, and MnS) were loaded on ZnIn2S4, the rates of H2 evolution over Pt-MS/ZnIn2S4 (MS = CoS, NiS, and MnS) were sharply decreased. Instead of the role as effective co-catalysts, these transition-metal sulfides (i.e., CoS, NiS, and MnS) may work as the recombination center of photo-generated electron-hole pairs, which lowered the photocatalytic activity for hydrogen evolution over Pt-MS/ZnIn2S4 (MS = CoS, NiS, and MnS). Further investigation is needed and also under way to provide enough supporting information to evidence the negative effects of CoS, NiS, and MnS, although main attention has focused on the more effective co-catalysts such as Ag2S, SnS, and CuS in the following discussion.

Bottom Line: After loading 1.0 wt.% CuS together with 1.0 wt.% Pt on ZnIn2S4, the activity for H2 evolution was increased by up to 1.6 times, compared to the ZnIn2S4 only loaded with 1.0 wt.% Pt.Here, transition-metal sulfides such as CuS, together with Pt, acted as the dual co-catalysts for the improved photocatalytic performance.This study indicated that the application of transition-metal sulfides as effective co-catalysts opened up a new way to design and prepare high-efficiency and low-cost photocatalysts for solar-hydrogen conversion.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China. ssmao@lbl.gov.

ABSTRACT
A series of Pt-loaded MS/ZnIn2S4 (MS = transition-metal sulfide: Ag2S, SnS, CoS, CuS, NiS, and MnS) photocatalysts was investigated to show various photocatalytic activities depending on different transition-metal sulfides. Thereinto, CoS, NiS, or MnS-loading lowered down the photocatalytic activity of ZnIn2S4, while Ag2S, SnS, or CuS loading enhanced the photocatalytic activity. After loading 1.0 wt.% CuS together with 1.0 wt.% Pt on ZnIn2S4, the activity for H2 evolution was increased by up to 1.6 times, compared to the ZnIn2S4 only loaded with 1.0 wt.% Pt. Here, transition-metal sulfides such as CuS, together with Pt, acted as the dual co-catalysts for the improved photocatalytic performance. This study indicated that the application of transition-metal sulfides as effective co-catalysts opened up a new way to design and prepare high-efficiency and low-cost photocatalysts for solar-hydrogen conversion.

No MeSH data available.