Bandgap engineering and plasmonically enhanced sun light photocatalyis in Au/Cd1−xZnxS nanocomposites

Abstract

Metal nanoparticles incorporated semiconductor nanomaterials generally holds a series of advantages especially enhanced electron-hole pair lifetime and thus exhibits superior solar energy conversions. In this study, we report a facile solution processing of Au incorporated Cd 1-x Zn x S, where x = 0, 0.25, 0.5, 0.75 & 1, nanocomposites and their enhanced photocatalytic applications. The Au/CdZnS nanocomposites were investigated for their structural, morphological, optical and photocatalytic properties. The XRD patterns indicated the crystalline sizes of CdZnS are found to fall with the range of 1-3 nm. The electron microscopic images publicized the average particle size of Cd 0.25 Zn 0.75 S is 4 nm. The bandgap values of pristine CdS, pristine ZnS, Cd 0.75 Zn 0.25 S, Cd 0.5 Zn 0.5 S and Cd 0.25 Zn 0.75 S are 2.21 eV, 3.4 eV, 2.29 eV, 2.31 eV and 2.53 eV, respectively. The optical band gap of the CdZnS nanomaterials have got reduced for Au incorporation due to the occurrence of red shift and the enhanced visible region absorption for the inclusion of Au. The visible light photocatalytic effect of the nanocomposites have been evaluated with methylene blue (MB) dye degradation reaction under sunlight light exposure. The Au incorporated Cd 0.25 Zn 0.75 S nanocompound had exhibited 97 % of photocatalytic degradation of MB dye molecules which is 20% higher than the bare Cd 0.25 Zn 0.75 S nanocompound.

CdS Nanorods with an Optimized ZnS Coating as Composite Photocatalysts for Enhanced Water Splitting under Solar Light Irradiation

“…The PL properties of pure CdS, Cd/Zn-3, and Cd/Zn-4 were measured using a 400 nm pulsed light excitation with an optical frequency-doubling system. As shown in Figure c, first, all of the three samples showed band edge emission spectrum peaks at around 550 nm, which were similar to the PL spectra of CdS as reported previously . The PL spectra of Cd/Zn-3 and Cd/Zn-4 showed two emission bands with peaks at about 477 and 493 nm, corresponding with the PL spectra of ZnS.…”

“…As shown in Figure 3c, first, all of the three samples showed band edge emission spectrum peaks at around 550 nm, which were similar to the PL spectra of CdS as reported previously. 33 The PL spectra of Cd/Zn-3 and Cd/Zn-4 showed two emission bands 34 with peaks at about 477 and 493 nm, corresponding with the PL spectra of ZnS. Considering the wider bandgap of ZnS than that of CdS, the excited charge carrier could tunnel through between the ZnS coating layer and CdS nanorods, which influenced the plasmon-induced PL intensity in the composite structures.…”

Pressure-Induced Bandgap Engineering and Tuning Optical Responses of Cd0.25Zn0.75S Alloy for Optoelectronic and Photovoltaic Applications

“…It should be noted that when pressure is applied, the maxima of the valence band shift downward while the minima of the conduction band shift upward, suggesting an increase in the bandgap with an increase in pressure. The GGA band structures at ambient pressure agree with those of 1.53 eV [ 27 ] and 1.60 eV [ 28 ], while the experimental results are 2.53 eV [ 24 ], 3.90 eV [ 36 ], and 4.25 eV [ 37 ]. This gives us the confidence to improve the bandgap using better functionals to overcome the underestimation of GGA results and further tune the optical responses to attain the desired device performance.…”

“…Photocurrent production in reduced graphene oxide–cadmium zinc sulfide nanocomposites under simulated solar light irradiation has been described for photodetection applications [ 23 ]. A structural, morphological, optical, and photocatalytic study was also conducted using plasmon-enhanced Au/Cd 1 − x Zn x S nanocomposites, and the Cd 0.25 Zn 0.75 S alloy bandgap was reported as 2.53 eV [ 24 ]. Theoretically, the thermodynamic properties of the ternary Cd 0.25 Zn 0.75 S alloy have been investigated using a quasi-harmonic model for pressures of 0–10 GPa and temperatures of 0–1200 K [ 25 ], whereas lattice thermal conductivity has been investigated for pressures of 0–10 GPa and temperatures of 300–1200 K, respectively [ 26 ].…”

Enhanced Photo-Catalytic and Antibacterial Properties of Ni-Doped Cd0.9Zn0.1S Nanostructures

“…The Au doped Cd 0.25 Zn 0.75 S nanostructures had exhibited 97% of photo-catalytic removal capacity of MB dye which is 20% superior to the Cd 0.25 Zn 0.75 S nanostructures [41]. Zn 0.3 Cd 0.7 S exhibited the maximum level of photo-catalytic activity and stability for the degradation of MO with k = 0.85 h −1 , which is 2.2 times higher than that of CdS [42].…”