Photocatalytic water reduction under visible light on a novel ZnIn2S4 catalyst synthesized by hydrothermal method

Abstract

A novel ZnIn 2 S 4 catalyst synthesized by hydrothermal method shows high and stable photocatalytic activity for water reduction under visible light illumination.In recent years photocatalytic water splitting using solar energy has received a great deal of attention because of the global energy and environmental problems. During the past decades many mixed oxide photocatalysts such as SrTiO 3 , 1 KNb 6 O 17 2 and NaTaO 3 3 have been reported to show high activity for overall water splitting. These photocatalysts, however, are effective only in the ultraviolet region due to their wide band gap. In order to improve the efficiency of utilizing the solar energy, the development of visible-light-driven photocatalysts for water splitting is indispensable. Unfortunately, the number of photocatalysts working under visible light irradiation is still limited. [4][5][6] In contrast to the metal oxide photocatalysts, many metal sulfides have the narrower band gaps that correspond to the visible light absorption. 7 The ternary sulfides with strong absorption in the visible region may be good candidates for photocatalytic water splitting to produce hydrogen. But, it is commonly believed that metal sulfides are unstable during the photocatalytic reaction. Improving the stability of metal sulfide catalyst such as CdS for water splitting is challenging. A few efforts have been made, for example, by incorporating the nanoparticles of metal sulfide into the interlayer 8 or mesoporous silica 9 to stabilize the metal sulfides. The preparation procedure is complicated and the photocatalytic efficiency is still very low. It has recently been reported that multicomponent metal sulfide 7 and oxysulfide 4 show stable photocatalytic activity for water reduction and oxidation. These results imply that the multicomponent metal sulfide could be a new class of stable photocatalyst for water reduction.Zinc indium sulfide, ZnIn 2 S 4 , is a ternary chalcogenide which belongs to the family of ternary compound AB 2 X 4 . ZnIn 2 S 4 is a potential photoconducting material 10 and has been extensively applied to the electrochemical recording and photovariable capacitor. But, there is no report on the photocatalytic water reduction over the ternary compound of AB 2 X 4 . These compounds are conventionally prepared by the chemical transport method. 11 This method usually requires high temperature and high vacuum, as well as a transporting agent such as iodine. In this communication, we report a chemically stable ZnIn 2 S 4 photocatalyst prepared by a direct hydrothermal synthesis method. UV-visible diffuse reflectance spectra shows that the absorption edge of ZnIn 2 S 4 is in the visible region, corresponding to the band gap of 2.3 eV. It is found that the ZnIn 2 S 4 shows high activity for photocatalytic water reduction under visible light (l > 420 nm) irradiation. More interestingly, the H 2 evolution rate gradually increases with prolonged photocatalytic reaction time. No deactivation is observed even after photocatalytic reaction for 150 h.The ZnS...

Hydrogen Production over Titania‐Based Photocatalysts

“…They are commonly used in chalcogenide photocatalyst systems, such as CdS, [45,116] ZnIn 2 S 4 , [117] CdIn 2 S 4 , [118] and ZnS, [119] because S 2À can react with 2 h + to form S 0 . Therefore, the corrosion of chalcogenide itself can be suppressed.…”

Water reduction and oxidation on Pt–Ru/Y2Ta2O5N2catalyst under visible light irradiation

“…Therefore, the development of visible-light responsive photocatalysts for overall water splitting is currently attracting much attention as a potentially efficient utilization of solar energy. [4][5][6] Considerable effort has been made to extend the absorption edge of semiconductors with wide bandgaps into the visible-light region. 7,8 The incorporation of non-metal atoms (C, N, F, P and S) into metal-oxide lattices is one way to narrow the bandgap of the parent oxide because of their p states mixing with O 2p states.…”

Nanocatalysts for Water Splitting

“…Lei et al prepared the ZnIn 2 S 4 photocatalyst with layered structure by a solvothermal method for the first time. 169 The ZnIn 2 S 4 photocatalyst has an intermediate band gap of 2.3 eV between those of ZnS and In 2 S 3 . ZnIn 2 S 4 alone can produce H 2 from aqueous Na 2 S/Na 2 SO 3 solution under visible light irradiation.…”