Silicon nanowire array/Cu₂O crystalline core–shell nanosystem for solar-driven photocatalytic water splitting

Abstract

P-type Cu2O nanocrystals were deposited on n-type silicon nanowire arrays (Si NWs) to form core-shell heterojunction arrays structure via a simple electroless deposition technique. Scanning electron microscopy, transmission electron microscope and x-ray diffraction were utilized to characterize the morphology and structure of the core-shell nanosystem. The reflectivity of the obtained core-shell structure measured by UV/vis spectrometry showed a comparatively low reflectivity in the visible-light region, which implied good optical absorption performance. The water splitting performance of the obtained Si NWs, planar Si/Cu2O structure and Si NW/Cu2O core-shell nanosystem were studied. Owing to the large specific surface area, heterojunctions formed between Cu2O nanocrystallites and Si NWs and the light trapping effect of the NW array structure, the photocatalytic performance of the Si NW/Cu2O core-shell nanosystem increased markedly compared with that of pure silicon NWs and a planar Si/Cu2O structure, which means excellent hydrogen production capacity under irradiation with simulated sunlight. In addition, the photocatalytic performance of the core-shell nanosystem was improved obviously after platinum nanoparticles were electrodeposited on it.

Review of one-dimensional and two-dimensional nanostructured materials for hydrogen generation

“…This concept of using an intrinsic electrical field is applied in H 2 generation. 59 n-n type heterojunctions yield similar results. 35 In the case of photo- 17 due to shorter collection times.…”

“…Forming a p-n heterojunction accelerates improves the separation of the photogenerated charge carriers. This was illustrated by Xiong et al 59 using Cu 2 O (p-type) as a core-shell structure with Pt as a co-catalyst. This composite structure showed a nearly 45% increase in the generation of H 2 compared with pristine Si NWs.…”

“…This composite structure showed a nearly 45% increase in the generation of H 2 compared with pristine Si NWs. In addition to p-n type heterojunctions, 59 n-n type heterojunctions have also been investigated in a similar core-shell structure with ZnO/Zn x Cd 1Àx Te NWs. 35 To put this in context, it is important to mention a study 36 which showed the selective isolation of electron-hole pairs in an n-n type heterojunction.…”

Hydrogen production using solar grade wasted silicon

“…Furthermore, photocatalytic water splitting is appropriate to carry out the reaction for the clean solar impetus and environment friendly by-products [18,19]. In consideration of a suitable conduction band potential for the reduction of water to form H 2 , silicon is indeed a potential photocatalyst for water splitting to produce H 2 [20]. This paper addresses two novel methods of hydrogen production using industrial slicing wasted silicon of solar cell grade.…”

“…The other approach to produce hydrogen is photocatalytic water splitting process using the recollected high purity silicon as a photocatalyst. As is well-known, recombination phenomena of silicon giving photoluminescence (PL) between photoexcited electrons and holes are drawbacks [21], which lead to a relatively low H 2 evolution kinetics in the photocatalytic system contained single photocatalyst Si alone [20]. Therefore Pt particles was loaded on Si by in-situ reduction of Chloroplatinic acid as co-catalyst to enhance the photocatalytic activity.…”