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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.


Schematic illustration of photo-generated charge-transfer process for photocatalytic hydrogen evolution over Pt-CuS/ZnIn2S4. From an aqueous solution containing Na2SO3/Na2S under simulated solar light.
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Figure 4: Schematic illustration of photo-generated charge-transfer process for photocatalytic hydrogen evolution over Pt-CuS/ZnIn2S4. From an aqueous solution containing Na2SO3/Na2S under simulated solar light.

Mentions: Figure 4 illustrates the process of photo-generated charge transfer for photocatalytic hydrogen evolution over Pt-CuS/ZnIn2S4 in an aqueous solution containing Na2SO3/Na2S under simulated sunlight. Band gap excitation produces electron-hole pairs in ZnIn2S4 particles. The excited electrons are subsequently channeled to Pt sites, which reduce protons to generate hydrogen. On the other hand, the valence band potential of ZnIn2S4, deduced from the conduction band potential (0.29 V vs. NHE) [22] and the band gap energy (2.43 eV), is about 2.72 V vs. NHE, which is more positive than the OH-/O2 redox potential [4]. The valence band potential of CuS is less positive than the OH-/O2 redox potential [34]. Such a difference of valence band potentials makes it possible for the excited holes to transfer from ZnIn2S4 to CuS to react with Na2S/Na2SO3 electron donor in the solution. Therefore, Pt and CuS are supposed to act as the reduction and oxidation co-catalyst, respectively, which leads to more efficient charge separation, thus improves photocatalytic activity of Pt-CuS/ZnIn2S4. Similar benefits of dual co-catalysts on photocatalytic activity have been observed for CdS loaded with noble metals as reduction catalysts and noble-metal sulfides as oxidation catalysts [29,30]. It is noteworthy that replacing noble-metal sulfides (such as PdS) by transition-metal sulfides (such as CuS) as the co-catalysts would help lower the cost of photocatalysts for solar-hydrogen production. Moreover, seeking effective co-catalyst candidates could be expanded to other transition-metal sulfides such as FeS and SnS2, etc. Detailed research on this subject is still an ongoing progress in our group.


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)

Schematic illustration of photo-generated charge-transfer process for photocatalytic hydrogen evolution over Pt-CuS/ZnIn2S4. From an aqueous solution containing Na2SO3/Na2S under simulated solar light.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Schematic illustration of photo-generated charge-transfer process for photocatalytic hydrogen evolution over Pt-CuS/ZnIn2S4. From an aqueous solution containing Na2SO3/Na2S under simulated solar light.
Mentions: Figure 4 illustrates the process of photo-generated charge transfer for photocatalytic hydrogen evolution over Pt-CuS/ZnIn2S4 in an aqueous solution containing Na2SO3/Na2S under simulated sunlight. Band gap excitation produces electron-hole pairs in ZnIn2S4 particles. The excited electrons are subsequently channeled to Pt sites, which reduce protons to generate hydrogen. On the other hand, the valence band potential of ZnIn2S4, deduced from the conduction band potential (0.29 V vs. NHE) [22] and the band gap energy (2.43 eV), is about 2.72 V vs. NHE, which is more positive than the OH-/O2 redox potential [4]. The valence band potential of CuS is less positive than the OH-/O2 redox potential [34]. Such a difference of valence band potentials makes it possible for the excited holes to transfer from ZnIn2S4 to CuS to react with Na2S/Na2SO3 electron donor in the solution. Therefore, Pt and CuS are supposed to act as the reduction and oxidation co-catalyst, respectively, which leads to more efficient charge separation, thus improves photocatalytic activity of Pt-CuS/ZnIn2S4. Similar benefits of dual co-catalysts on photocatalytic activity have been observed for CdS loaded with noble metals as reduction catalysts and noble-metal sulfides as oxidation catalysts [29,30]. It is noteworthy that replacing noble-metal sulfides (such as PdS) by transition-metal sulfides (such as CuS) as the co-catalysts would help lower the cost of photocatalysts for solar-hydrogen production. Moreover, seeking effective co-catalyst candidates could be expanded to other transition-metal sulfides such as FeS and SnS2, etc. Detailed research on this subject is still an ongoing progress in our group.

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.