Reliable Bi-Functional Nickel-Phosphate /TiO2 Integration Enables Stable n-GaAs Photoanode for Water Oxidation under Alkaline Condition: Article No. 5429

Maheswari Arunachalam, Rohini Subhash Kanase, Kai Zhu, Soon Hyung Kang

Research output: Contribution to journalArticlepeer-review

7 Scopus Citations

Abstract

Hydrogen is one of the most widely used essential chemicals worldwide, and it is also employed in the production of many other chemicals, especially carbon-free energy fuels produced via photoelectrochemical (PEC) water splitting. At present, gallium arsenide represents the most efficient photoanode material for PEC water oxidation, but it is known to either be anodically photocorroded or photopassivated by native metal oxides in the competitive reaction, limiting efficiency and stability. Here, we report chemically etched GaAs that is decorated with thin titanium dioxide (~30 nm-thick, crystalline) surface passivation layer along with nickel-phosphate (Ni-Pi) cocatalyst as a surface hole-sink layer. The integration of Ni-Pi bifunctional co-catalyst results in a highly efficient GaAs electrode with a ~100 mV cathodic shift of the onset potential. In this work, the electrode also has enhanced photostability under 110 h testing for PEC water oxidation at a steady current density Jph > 25 mA cm-2. The Et-GaAs/TiO2/Ni-Pi|Ni-Pi tandem configuration results in the best unassisted bias-free water splitting device with the highest Jph (~7.6 mA cm-2) and a stable solar-to-hydrogen conversion efficiency of 9.5%.
Original languageAmerican English
Number of pages11
JournalNature Communications
Volume14
DOIs
StatePublished - 2023

NREL Publication Number

  • NREL/JA-5900-87139

Keywords

  • GaAs
  • photoanode
  • photoelectrochemical cell
  • stability
  • surface coating

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