III–V core / oxide shell nanowires for light–driven water splitting

Thomas Dursap , M. Fadel , C. Tapia Garcia , Philippe Regreny (1) , Céline Chevalier (2) , Alexandre Danescu (1) , Matthieu Koepf , Vincent Artero , Matthieu Bugnet , Jose Penuelas (1)

1 INL - MFN - INL - Matériaux Fonctionnels et Nanostructures
2 INL - I-Lum - INL - Ingénierie et conversion de lumière (i-Lum)

Photoelectrochemical cells (PEC) are one of the most promising approaches for the production of alternative energy carrier in the global effort to diminish the usage of fossil fuels [1]. In this context, III-V nanowires (NWs) based photoelectrodes [2, 3] are particularly attractive thanks to their high surface/volume ratio, efficient charge separation and collection and their light trapping potential. However, III-V NWs suffer from corrosion in aqueous electrolyte, which prevents their utilization for a long period. In order to avoid the surface degradation of the NWs under working conditions, a particular attention has to be given to their surfaces. We proposed to grow an oxide shell, transparent to visible light and compatible with the carrier transfer from the III-V semiconductor to the electrolyte, to increase the viability of these photoelectrodes. GaAs NWs were grown by molecular beam epitaxy (MBE) using the vapor-liquid-solid (VLS) mechanism on silicon substrate [4, 5], and a TiO2 shell was deposited by atomic layer deposition (ALD). The morphology, and interface of the NWs were studied by scanning transmission electron microscopy and electron energy-loss spectroscopy. Measurements performed on the PEC revealed an enhancement of the photoactivity by a factor 20 comparing a thin layer of GaAs and optimized GaAs NWs, reaching a current density of around 1.2 mA/cm² at 0.0 V vs RHE [6]. [1] N. Armaroli et al, Angew. Chem. 46, (2007), 52 [2] M. G. Kibria et al, Nat. Commun. 5 (2014), 3825 [3] N. Kornienko et al, ACS Nano 10 (2016), 5525 [4] T. Dursap, et al, Nanoscale Adv., 2, (2020), 2127-2134 [5] T. Dursap, et al, Nanotechnology, 32, (2021), 155602 [7] This work was done as part of the ANR BEEP project (ANR-18-CE05-0017)

Domaines: Matériaux; Micro et nanotechnologies/Microélectronique

Thomas Dursap, M. Fadel, C. Tapia Garcia, Philippe Regreny, Céline Chevalier, et al.. III–V core / oxide shell nanowires for light–driven water splitting. Nanowire Week 2022, Apr 2022, Chamonix, France. ⟨hal-03656629⟩