Hierarchical Ternary Sulfides as Effective Photocatalyst for Hydrogen Generation Through Water Splitting: A Review on the Performance of ZnIn2S4

Abstract

One of the major aspects and advantages of solar energy conversion is the photocatalytic hydrogen generation using semiconductor materials for an eco-friendly technology. Designing a low-cost efficient material to overcome limited light absorption as well as rapid recombination of photogenerated charge carriers is essential to achieve considerable hydrogen generation. In recent years, sulfide based semiconductors have attracted scientific research interest due to their excellent solar response and narrow band gap. The present review focuses on the recent approaches in the development of hierarchical ternary sulfide based photocatalysts with a special focus on ZnIn2S4. We also observe how the electronic structure of ZnIn2S4 is beneficial for water splitting and the various strategies involved for improving the material efficiency for photocatalytic hydrogen generation. The review places emphasis on the latest advancement/new insights on ZnIn2S4 being used as an efficient material for hydrogen generation through photocatalytic water splitting. Recent progress on essential aspects which govern light absorption, charge separation and transport are also discussed in detail.

Recent Advances in Nanoscale Engineering of Ternary Metal Sulfide-Based Heterostructures for Photocatalytic Water Splitting Applications

“…49 In addition, it is well-known that the presence of p-block ions with d 10 configuration (e.g., In 3+ ) endows TMSs with excellent photocatalytic performance. 50 Thus, extensive research studies have been focused on TMS-based heterostructures containing In 3+ (e.g., ZnIn 2 S 4 , CdIn 2 S 4 , CaIn 2 S 4 , etc.) toward enhancing the photocatalytic water splitting performance and the corresponding photostability in realizing practical H 2 generation.…”

“…10−19 However, metal oxides consist of deep O-2p orbitals in the VB, resulting in the effective band gap falling under the ultraviolet (UV) region, which limits the solar spectrum utilization. 20 In addition, because of the high affinity of hydrogen with O atoms, metal oxides often suffer from hydrogen embrittlement, which eventually reduces the durability in the solar-driven HER. 21 On the other hand, ternary metal sulfides (TMSs) have been extensively reported as suitable H 2 evolution photocatalysts (HEPs) owing to the appealing nature of (1) the more electronegative potential of S-3p than O-2p orbitals, resulting in a narrower E g to utilize a broader solar spectrum, (2) larger exposed active sites, (3) wide variety and diversified chemical structures, (4) relatively lower hydrogen embrittlement than metal oxides, and (5) higher chemical and photostability than binary metal sulfides.…”

“…In this context, metal sulfides and metal oxides have been adequately documented as two of the most representative classes of semiconductor materials in photocatalytic applications attributed to their unique intrinsic properties and relatively high abundancy. − However, metal oxides consist of deep O-2p orbitals in the VB, resulting in the effective band gap falling under the ultraviolet (UV) region, which limits the solar spectrum utilization . In addition, because of the high affinity of hydrogen with O atoms, metal oxides often suffer from hydrogen embrittlement, which eventually reduces the durability in the solar-driven HER .…”

“…In addition, because of the high affinity of hydrogen with O atoms, metal oxides often suffer from hydrogen embrittlement, which eventually reduces the durability in the solar-driven HER . On the other hand, ternary metal sulfides (TMSs) have been extensively reported as suitable H 2 evolution photocatalysts (HEPs) owing to the appealing nature of (1) the more electronegative potential of S-3p than O-2p orbitals, resulting in a narrower E g to utilize a broader solar spectrum, (2) larger exposed active sites, (3) wide variety and diversified chemical structures, (4) relatively lower hydrogen embrittlement than metal oxides, and (5) higher chemical and photostability than binary metal sulfides. − Even so, the photocatalytic HER performance of pristine TMS is still not up to a satisfactory level for practical applications due to severe photocorrosion, fast recombination of photogenerated electron–hole pairs, short carriers lifetime, and sluggish charge migration kinetics to active sites that hamper its development. , Hitherto, incessant research efforts have been devoted to surmounting the inherent drawbacks of TMSs. Various enhancement strategies including elemental doping, vacancy engineering, cocatalysts deposition, morphology control, heterostructures formation, etc.…”

Shining light on ZnIn2S4 photocatalysts: Promotional effects of surface and heterostructure engineering toward artificial photosynthesis

“…In virtue of the burgeoning interests in ZnIn 2 S 4 -based photocatalysis, with a number of review articles emerged in this domain, [56][57][58][59][60] less focus has been dedicated to the correlation between the material structure and the resulting photocatalytic activity, charge transfer dynamics to boot. In response to the urge of promoting further progress of ZnIn 2 S 4 -related studies for the aforementioned applications, a contemporary review is required to review the recent advances in ZnIn 2 S 4 photocatalyst research over the past 4 years, with an emphasis on the structure-activity relationship.…”