Hierarchically self-assembled ZnO architectures: Establishing light trapping networks for effective photoelectrochemical water splitting

Tian Feng Hou, Ramireddy Boppella, Arunkumar Shanmugasundaram, Dong Ha Kim, Dong Weon Lee

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Here we develop photoanodes based on hierarchical zinc oxide (ZnO) nanostructures such as vertically aligned nanorods (NR), nanorods interconnected by thin nanosheets (NR@TN) and nanorods interconnected by dense nanosheets (NR@DN). The morphological variations were successfully controlled by secondary growth time and the plausible formation mechanisms of these hierarchical ZnO architectures were explained based on the experiment analysis. Under simulated light illumination (AM 1.5, 100 mW cm2), NR@TN produced a photocurrent density of 0.62 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (vs. RHE). Importantly, 35% enrichment in photoconversion efficiency was observed for NR@TN at much lower bias potential (0.77 V vs. RHE) compared with NR (0.135%) and NR@DN (0.13% at 0.82 V vs. RHE). Key to the improved performance is believed to be synergetic effects of excellent light-trapping characteristics and the large surface-to-volume ratios due to the nanosheet structures. The nanorod connected with thin nanosheet structures improved the efficiency by means of improved charge transfer across the nanostructure/electrolyte interfaces, and efficient charge transport within the material. We believe that the hierarchical ZnO structures can be used in conjunction with doping and/or sensitization to promote the photoelectrochemical (PEC) performance. Further, the ZnO nanorod interconnected with nanosheets morphology presented in this article is extendable to other metal oxide semiconductors to establish a universal protocol for the development of high performance photoanodes in the field of PEC water splitting.

Original languageEnglish
Pages (from-to)15126-15139
Number of pages14
JournalInternational Journal of Hydrogen Energy
Volume42
Issue number22
DOIs
StatePublished - 1 Jun 2017

Keywords

  • Hydrothermal synthesis
  • Light trapping
  • Photoelectrochemical water splitting
  • ZnO hierarchical architectures

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