|Title:||An integrated cobalt disulfide (CoS2) co-catalyst passivation layer on silicon microwires for photoelectrochemical hydrogen evolution||Authors:||CHIH-JUNG CHEN
|Issue Date:||2015||Journal Volume:||3||Journal Issue:||46||Start page/Pages:||23466-23476||Source:||Journal of Materials Chemistry A||Abstract:||
An integrated cobalt disulfide (CoS2) co-catalyst passivation layer on Si microwires (MWs) was used as a photocathode for solar hydrogen evolution. Si MWs were prepared by photolithography and dry etching techniques. The CoS2-Si photocathodes were subsequently prepared by chemical deposition and thermal sulfidation of the Co(OH)2 outer shell. The optimized onset potential and photocurrent of the CoS2-Si electrode were 0.248 V and -3.22 mA cm-2 (at 0 V), respectively. The best photocatalytic activity of the CoS2-Si electrode resulted from lower charge transfer resistances among the photoabsorber, co-catalyst, and redox couples in the electrolyte. X-ray absorption near edge structure was conducted to investigate the unoccupied electronic states of the CoS2 layer. We propose that more vacancies in the S-3p unoccupied states of the CoS2-Si electrode were present with a lower negative charge of S22- to form weaker S-H bond strength, promoting water splitting efficiency. Moreover, the CoS2 co-catalyst that completely covered underlying Si MWs served as a passivation layer to prevent oxidation and reduce degradation during photoelectrochemical measurements. Therefore, the optimal CoS2-Si electrode maintained the photocurrent at about -3 mA cm-2 (at 0 V) for 9 h, and its hydrogen generation rate was approximately 0.833 μmol min-1. © 2015 The Royal Society of Chemistry.
|DOI:||10.1039/c5ta06202k||SDG/Keyword:||Catalysts; Charge transfer; Cobalt; Electrochemistry; Electrodes; Electrolytes; Electronic states; Field emission cathodes; Hydrogen production; Passivation; Photocathodes; Photolithography; Silicon; Solar power generation; X ray absorption; X ray absorption near edge structure spectroscopy; Charge transfer resistance; Dry etching techniques; Hydrogen generations; Photocatalytic activities; Photoelectrochemical hydrogen; Photoelectrochemical measurements; Unoccupied electronic state; X ray absorption near edge structure; Transition metal compounds
|Appears in Collections:||化學系|
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