Optimization of Ag₂S Quantum Dots Decorated ZnO Nanorod Array Photoanodes for Enhanced Photoelectrochemical Performances

Abstract

The synthesis of Ag2S quantum dots (QDs) deposited on the surface of electrodeposited ZnO nanorods (NRs) by a successive ionic-layer adsorption and reaction (SILAR) method is reported. A Box-Behnken response surface factorial design was used to organize the experiments conducted and identify the effects of three electrochemical parameters and their potential interactions. These parameters include zinc precursor concentration in the electrolytic bath, the electrolytic bath temperature and the electrodeposition time on the morphological and structural properties of the electrochemically grown ZnO nanorods. Morphological, structural and optical characterizations of these NRs heterojunctions were done. A direct band gap for Ag2S QDs, tuned between 2.54 and 2.73 eV by varying the SILAR cycle numbers, was determined. The presence of ZnO nanostructures increases the light scattering capability of the samples, allowing an important quantity of diffuse light near the absorption edge of Ag2S. The photoelectrochemical performance of these ZnO NRs decorated with Ag2S QDs based photoanodes has been evaluated. The SILAR parameters related to the growth of the Ag2S QDs that optimize the performance of this photoelectrode are presented. The effect of a ZnS passivation layer has been studied leading to an increase of about 400% in the short-circuit current density after passivation.

Improving Photoelectrochemical Activity of a Silver Sulfide-Based Photoelectrode by Bismuth Doping for Hydrogen Evolution from Industrial Waste Water

“…The synergistic effect between the aforementioned electrolyte engineering, morphology control, and doping treatment renders the H 2 evolution rate over Bi:Ag 2 S/ZnO NRs as the photoelectrode markedly accelerated, as evidently manifested in its photocurrent density reaching 7 mA cm –2 (at ∼−0.35 V vs Ag/AgCl) under 1 sun illumination. Such outstanding performance, which far exceeds those reported for additional Ag 2 S-based photoelectrodes in the literature, clearly punctuates the great promise of the Bi:Ag 2 S/ZnO NRs developed in this work. ,− …”

“…Most notably, such outperformance is further seen in the comparison with those reported for Ag 2 S-based photoelectrodes in the literature, leading to Bi:Ag 2 S/ZnO NRs-6 brought into the forefront of the following discussions on the influences of the Bi 3+ dopant on the optical, electrical, and PEC properties of Bi:Ag 2 S/ZnO NRs (Table ). ,− To this end, undoped Ag 2 S/ZnO NRs as the reference are particularly prepared under almost the same conditions. Its photocurrent response under solar irradiation is first measured by means of LSV and further plotted in parallel with that of Bi:Ag 2 S/ZnO NRs for comparison to in this way highlight the major differences lying, on the one hand, in the saturation photocurrent density ( J sat ) (Figure b).…”

Band alignment of ZnO-based nanorod arrays for enhanced visible light photocatalytic performance

“…The ZnO nanorod arrays were fabricated on FTO substrates by a hydrothermal method, 17 while the MoS 2 and Ag 2 S coating layers were synthesized, respectively by a solvothermal method 18 and a successive ionic-layer adsorption and reaction (SILAR) process. 19 Specifically, for the ZnO nanorod arrays, a layer of ZnO seed layer in 30 nm thickness was deposited on the cleaned FTO substrates by a TALD-100-2H1R ALD system from Ke-Micro Company (Jiaxing, China). Afterwards, the substrates were inverted in the solution containing 20 mM Zn(CH 3 COO) 2 ·2H 2 O and 20 mM C 6 H 12 N 4 at 90 °C for 80 min to grow the ZnO nanorods.…”

Vertically Aligned Nanowires and Quantum Dots: Promises and Results in Light Energy Harvesting

“…However, these very brilliant techniques have never been combined together in a new solar cell. Other recent studies report the use of different types of nanowires [ 110 ] or quantum dots on NWs of ZnO [ 111 ], but with poor results (PCE < 1%); therefore, we concentrate our further comparative analysis on solar cells with nanowires embedded in perovskite layers or functionalized with perovskite QDs (PQDs) (see Table 3 and Table 4 ).…”