Enhancement of Hydrogen Productions by Accelerating Electron-Transfers of Sulfur Defects in the CuS@CuGaS2 Heterojunction Photocatalysts

Abstract

CuS and CuGaS 2 heterojunction catalysts were used to improve hydrogen production performance by photo splitting of methanol aqueous solution in the visible region in this study. CuGaS 2 , which is a chalcogenide structure, can form structural defects to promote separation of electrons and holes and improve visible light absorbing ability. The optimum catalytic activity of CuGaS 2 was investigated by varying the heterojunction ratio of CuGaS 2 with CuS. Physicochemical properties of CuS, CuGaS 2 and CuS@CuGaS 2 nanoparticles were confirmed by X-ray diffraction, ultraviolet visible spectroscopy, high-resolution transmission electron microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Compared with pure CuS, the hydrogen production performance of CuGaS 2 doped with Ga dopant was improved by methanol photolysis, and the photoactivity of the heterogeneous CuS@CuGaS 2 catalyst was increased remarkably. Moreover, the 0.5CuS@1.5CuGaS 2 catalyst produced 3250 µmol of hydrogen through photolysis of aqueous methanol solution under 10 h UV light irradiation. According to the intensity modulated photovoltage spectroscopy (IMVS) results, the high photoactivity of the CuS@CuGaS 2 catalyst is attributed to the inhibition of recombination between electron-hole pairs, accelerating electron-transfer by acting as a trap site at the interface between CuGaS 2 structural defects and the heterojunction.

Plasmonic AuPt@CuS Heterostructure with Enhanced Synergistic Efficacy for Radiophotothermal Therapy

“…21 According to the deconvoluted S element spectrum, the S 2p 3/2 peak is located at 162.06 eV, matching the value of S 2− reported in the literature (Figure 1i). 22 The peak presented at 163.31 eV corresponds to the S 2p 1/2 sulfur vacancy (V S ), 23 which results from the preferential bonding of S atoms to both Au and Pt atoms at the heterojunction interface owing to the larger Pauling electronegativity of Au (2.54) and Pt (2.28), compared to that of Cu (1.90), leading to the formation of V S in the CuS lattice. These interfacial V S defects cause an increase in the carrier density and then intensive resonance absorbance, finally contributing to the enhancement of photothermal performance upon NIR irradiation.…”

Graphdiyne (CnH2n−2) coupled with ZnCo-MOF double S-scheme heterojunction forms an efficient electron transport layer and its characterizationvia in situXPS

“…Accordingly, hydrogen (H 2 ) production via the photocatalytic process has generated significant interest due to its eco-friendly and cost effective nature. [5][6][7][8] Presently, the photocatalytic hydrogen evolution reaction, a semi-reaction of water fission, is being intensively studied by researchers due to its ability to convert indeterminate solar energy into storable and transportable synthetic forms of energy, as well as its high density and the nonpolluting nature of the water combustion products. [8][9][10] To date, numerous semiconductor photocatalysts have been developed for the production of hydrogen gas by hydro fission.…”

Constructing Er-Doped ZnO/CuS/Au Core-Shell Nanowires with Enhanced Photocatalytic and SERS Properties

“…Recently, different kinds of metal sulfides have attracted a large amount of attention because of their unique chemical and physical properties [1][2][3][4]. Among them, copper sulfide (CuS) is an essential p-type semiconductor with a narrow bandgap (1.2-2.3 eV), which shows many unique optical, electronic, and other physicochemical properties [5][6][7][8]. In addition, CuS has outstanding potential in variable applications, such as lithium-ion batteries, chemical sensors, solar energy converters, cathode material, photocatalysis, optical filters, and non-linear optical material [9][10][11].…”

“…In order to overcome this drawback, CuS nanostructures combined with various semiconductor materials can be used to improve their photocatalytic activity [27]. Presently, there are several different kinds of CuS-semiconductor heterostructures synthesized for significantly enhanced photocatalytic efficiency, such as BiOCl/CuS [28], CuS/ZnS [25,29], ZnO/CuS [27,30], CuS/TiO 2 [31], PrGO (partially reduced graphene oxide)/CuS [12], and CuS@CuGaS 2 [8]. Among them, ZnO/CuS heterostructures have attracted extensive interest because of their special bandgap location, which can inhibit the recombination of photogenerated charge carriers by preventing photocorrosion from enhancing their photocatalytic activity [32].…”