Graphene‐doped ZnS nanoparticles synthesized via hydrothermal route for enhanced electrocatalytic performance

Abstract

Energy and ecological issues increase high stress on the growth of a sustainable energy system. Better electrocatalysts is an imperative way to achieve this goal. This manuscript highlights the electronic energy state and surface area engineering of zinc sulfide (ZnS) in the nanoscale regime. These properties make ZnS, an appropriate electrocatalyst for various energy applications. It was attained by controlling the concentration of graphene into ZnS nanoparticles. Graphene‐doped ZnS nanoparticles were synthesized by simple hydrothermal route. Graphene hugely affects the structural, surface, optical, and electrochemical properties of ZnS nanoparticles. Here, 10% doping of graphene into ZnS nanoparticles double its surface area, and consequently, all other properties get varied. This sample shows the highest specific surface area of 143.05 m2/g and the highest pore diameter value of 6.02 nm. Electrocatalytic performance for synthesized samples has been verified using electrochemical impedance spectra (EIS) and cyclic voltammetry (CV) analysis. Using CV data analysis, peak current response with scan rate suggests that synthesized samples with higher graphene concentration have poor capacitive behavior. ZnS with 10% concentration of graphene possesses the highest capacitive behavior due to the fast transfer of charge/ions. Rate of flow of charge/ions into or on the electrodes is measured by a quantity called diffusion coefficient, have been calculated. Hence, the optimization of the doping concentration of graphene on ZnS is essential to obtain enhanced properties for energy applications. Also, the large concentration of graphene shield the absorption of electrolyte on ZnS surface, leading to weak electrocatalytic performance. EIS analysis reveals that smaller solution resistance and charge transfer resistance values are a sign of better electrical conductivity and electrocatalytic activity of the electrode materials. Various other characteristics studies like field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), and X‐ray photoelectron spectroscopy (XPS) have been done to confirm graphene‐doped ZnS nanoparticles’ formation and compare the properties variation from pure ZnS to graphene‐doped ZnS nanoparticles.

Diffusion Controlled Features of Microwave Assisted ZnS/ZnO Nanocomposite with Reduced Band Gap

“…14. It is clearly evident from the plot that the lower frequency region has high impedance value whereas it decreases as frequency increases, showing diffusion behavior and hence a standard phenomenon for solar cell applications, 28,30,31…”

“…16 Peak at 1367 cm −1 depicts C=O stretching and wave number 1429 cm −1 represents stretching for C=C bond. Functional groups such as C=S shown at 1738 cm −1 and sp hybridized C-C bond at 2175 cm −1 , 19,28 The wavenumber 2042 cm −1 gives C-N peak 19 and the wave number ECS Journal of Solid State Science and Technology, 2023 12 034004 3023 cm −1 represent C-H stretching. As ZnO fingerprint peak is always below 500 cm −1 but due to our equipment wave number range limitations we could not observed that.…”

Electrochemical analysis of thermally treated two dimensional zinc sulphide hexagonal nano-sheets with reduced band gap

“…However in most of the recent study for electrochemical performance of ZnS performed by Medha et al showed prominent reduction peak. However the present material due to its morphological 2D structure and reduced band gap depicts both oxidation and reduction behaviour [21][22][23]54]. In contrast, the CV of CoO (cobalt oxide) and MnO (manganese oxide) may exhibit different characteristics.…”

“…It is an n-type material which shows polymorphism as it usually exhibits a cubic phase structure which shows a transition to hexagonal wurtzite structure at ∼1000 °C. Cubic ZnS has a band gap of 3.37 eV whereas wider band gap wurtzite phase shows a wider band gap of 3.9 eV [21][22][23]. It is explored in a wide variety of applications such as ultraviolet-light-emitting diodes, flat-panel displays, electroluminescent, sensors and photovoltaic devices [24][25][26][27][28][29][30][31][32].…”

Fabrication of tunable band gap carbon based zinc nanocomposites for enhanced capacitive behaviour

“…The list of observed vibrational bands are listed in table 4. The peaks at wavenumbers 3449 cm −1 , 3327 cm −1 , 3473 cm −1 and 3473 cm −1 correspond to O-H bond [47][48][49][50]. It is observed that CSD has C-O, C=O, C-H, C=C bonds present at 1217 cm −1 , 1715 cm −1 , 790 cm −1 and 1026 cm −1 positions, respectively [51].…”