Hydrogenated ZnIn₂S₄ microspheres: boosting photocatalytic hydrogen evolution by sulfur vacancy engineering and mechanism insight

Abstract

The correlation between hydrogenation-induced surface sulfur vacancies and photocatalytic activity of hydrogenated ZnIn2S4 is tentatively proposed in this work.

Interfacial Chemical Bond and Internal Electric Field Modulated Z-Scheme Vs-ZnIn2S4/MoSe2 Photocatalyst for Efficient Hydrogen Evolution

“…Chen et al prepared a hydrogenated ZnIn 2 S 4 (H-ZIS) microspheres with sulfur vacancies for photocatalytic H 2 evolution. The results demonstrates that the hydrogen evolution rate of H-ZIS is as high as 1.9 mmol•g -1 •h -1 (nearly 8.6 times that of the pristine ZIS sample) 14 . However, as known from the reported literatures, the only defects introduction is not enough for realizing e cient photocatalytic property.…”

“…In comparison, the S 2p 3/2 and 2p 1/2 of Vs-ZIS presented evident negative-shift of about 0.14 eV and 0.19 eV, respectively, verifying the generation of S vacancies in ZIS. The S-vacancies can serve as strong electron-withdrawing group for facilitating the ZIS electrons transfer to S-vacancies, thus decreasing the equilibrium electron cloud density of S atoms inside ZIS, and further leading to the decreased binding energy 35,36 . Furtherly, it can be noted that the S 2p 3/2 and 2p 1/2 of Vs-ZIS/MoSe 2 exhibited a positive-shift of about 0.13 and 0.17 eV compared to that of Vs-ZIS, which should be caused by the strong interfacial interaction between MoSe 2 and Vs-ZIS 31 .…”

One-step hydrothermal synthesis of S-defect-controlled ZnIn2S4 microflowers with improved kinetics process of charge-carriers for photocatalytic H2 evolution

“…Owing to unique structural properties, including large specific surface area, short charge-separation channel as well as abundant surface active sites, nowadays, the two-dimensional (2D) layered metal-sulfide semiconductors have emerged as a class of promising photocatalysts for realizing the highly-efficient photocatalytic H 2 evolution upon visible light irradiation [14][15][16][17][18]. Among various 2D layered metal-sulfide semiconductors, the ternary metal sulfide of hexagonal ZnIn 2 S 4 , which is a member of AB 2 X 4 family semiconductors with a layered structure, is more popular, mainly owing to its broad visible-light absorption, strong protons reducibility as well as satisfactory chemical stability [9,11,19,20]. Nevertheless, the fast recombination process of photoinduced charge-carriers and the poor migration behavior of photoinduced electrons are still the two serious drawbacks to limit the photocatalytic activity of the 2D ZnIn 2 S 4 for H 2 evolution [21,22].…”

“…Therefore, the defect-modulation engineering on the ZnIn 2 S 4 NSs-based photocatalysts has been regarded as an effective strategy to enhance their photocatalytic activity for H 2 evolution [23,36]. For instance, Wang et al constructed the surface S-vacancy defect in the hydrothermal-produced ZnIn 2 S 4 microspheres through the pressure hydrogenation method, which resulted in the improved separation process of photoinduced charge-carriers and thus the enhanced photocatalytic activity for H 2 evolution [20]. Zhang et al reported that the S-vacancies on the Zn facets in monolayered ZnIn 2 S 4 could be obtained through the ion intercalation-exfoliation treatment of the hydrothermalproduced ZnIn 2 S 4 microspheres [24].…”

“…They also demonstrated that these confined S-vacancy defects built an important link between the electronic manipulation and photocatalytic activities of ZnIn 2 -S 4 . However, to date, most of the used strategies to dig the lattice defects of ZnIn 2 S 4 are mainly based on the secondary treatment of hydrothermal-produced ZnIn 2 S 4 micro/nanostructures using the complex physical or/and chemical processes [20,23,24], which inevitably increase the producing cost and time. What's more, an inappropriate secondary treatment of the ZnIn 2 S 4 micro/nanostructures may also induce their crystal-structure destroy rather than the surface S-vacancy defects.…”