Defect Engineering and Phase Junction Architecture of Wide-Bandgap ZnS for Conflicting Visible Light Activity in Photocatalytic H₂ Evolution

Abstract

ZnS is among the superior photocatalysts for H2 evolution, whereas the wide bandgap restricts its performance to only UV region. Herein, defect engineering and phase junction architecture from a controllable phase transformation enable ZnS to achieve the conflicting visible-light-driven activities for H2 evolution. On the basis of first-principle density functional theory calculations, electron spin resonance and photoluminescence results, etc., it is initially proposed that the regulated sulfur vacancies in wurtzite phase of ZnS play the key role of photosensitization units for charge generation in visible light and active sites for effective electron utilization. The symbiotic sphalerite-wurtzite phase junctions that dominate the charge-transfer kinetics for photoexciton separation are the indispensable configuration in the present systems. Neither ZnS samples without phase junction nor those without enough sulfur vacancies conduct visible-light photocatalytic H2 evolution, while the one with optimized phase junctions and maximum sulfur vacancies shows considerable photocatalytic activity. This work will not only contribute to the realization of visible light photocatalysis for wide-bandgap semiconductors but also broaden the vision on the design of highly efficient transition metal sulfide photocatalysts.

Construction of dual-channel for optimizing Z-scheme photocatalytic system

“…UV-Vis diffuse reflectance spectroscopy (DRS) is measured by a Carry 500 UV-Vis spectrophotometer, during which BaSO 4 is served as the background. The photoelectrochemical measurement is similar to previous report [21] . The …”

“…Fortunately, some previous studies have proved that introducing electron mediators (including Au [21][22][23] , Ag [16,24,25] , reduced graphene oxide [26] and so on) at the interface between PS Ⅰ and PS Ⅱ could reduce the transmission impedance of electrons and improve electron transfer rate across the interface, in which electron mediators act as a transfer channel for carriers. Regrettably, because free electron and hole are photo-excited simultaneously at the surface of PS Ⅰ or PS Ⅱ, and the isotropic migration of photo-induced electron-hole pairs from the bulk to surface of each semiconductor, opposite charge carriers can accumulate inevitably in the surface and its density will gradually increase, inducing serious surface self-recombination [20] .…”

Synergetic effect of CuS@ZnS nanostructures on photocatalytic degradation of organic pollutant under visible light irradiation

“…[9][10][11][12] Among the photocatalysts, zinc sulde (ZnS) has been studied extensively by several researchers. 13 ZnS is an important II-VI group semiconductor, which can rapidly produce electron-hole pairs by photoexcitation and thus create high negative potentials of the excited electron. The theoretical efficiency of the photo-carrier generation of ZnS is much higher than that of TiO 2 because of a direct band gap.…”

An Effective Electrical Throughput from PANI Supplement ZnS Nanorods and PDMS-Based Flexible Piezoelectric Nanogenerator for Power up Portable Electronic Devices: An Alternative of MWCNT Filler

“…[17][18][19] Furthermore, the wurtzite structures of ZnO, GaN, ZnS and CdSe have received vivid attraction because of their unique noncentrosymmetric structures. [20][21][22][23] Among the wurtzite classes, the noncentrosymmetric ZnS also possess a promising semiconducting property and thus suitable for wide range of applications, for instance, UV nanolasers, 24 micro force active sensors, 22 optoelectronic devices, 25 photocatalysts, 26 ultraviolet-light sensors 27 etc. Recently, Chen et al have reported stress induced white and green light emissions from a ZnS based device generated from bending, stretching and even by writing.…”