| Popis: |
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) |
