Author(s): Xiao-Qing Bao ; Petrovykh, D. Y. ; Alpuim, P. ; Stroppa, Daniel G. ; Guldris, Noelia ; Fonseca, Helder ; Costa, Margaret ; Gaspar, Joao ; Chuanhong Jin ; Lifeng Liu
Date: 2015
Persistent ID: https://hdl.handle.net/1822/49828
Origin: RepositóriUM - Universidade do Minho
Subject(s): Silicon microwire; Photocathode; Water reduction; Molybdenum oxysulfide; Hydrogen evolution reaction; Silicon nanostructure; Photoelectrochemical water splitting; Electrocatalysis
We report the fabrication of p-type silicon (Si) photocathodes consisting of well-ordered Si microwire (Si-MW) arrays coupled with non-precious and earth-abundant amorphous oxygen-rich molybdenum oxysulfide (MoOxSy) as both a hydrogen evolution catalyst and a passivation layer. The MoOxSyis conformally grown on the Si-MW surface through photo-assisted cyclic voltammetric (CV) deposition. By adjusting the cycle numbers of the CV deposition, Si-MW array electrodes with different MoOxSy catalyst loadings (Si-MWs@MoOxSy) have been obtained and comprehensively characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X- ray photoelectron spectroscopy (XPS), and Raman and Fourier-transform infrared spectroscopies. The photoelectrochemical performance of the Si-MWs@MoOxSycathodes toward water reduction is investigated and compared with that of platinum nanoparticle decorated Si-MW array electrodes (Si-MWs@PtNPs). An optimized Si-MWs@MoOxSyphotocathode is found to exhibit activity compar- able to that of the Si-MWs@PtNPs one, with a much better stability in acidic medium. In neutral electrolyte, Si-MWs@MoOxSyoutperforms Si-MWs@PtNPs in terms of both activity and stability. Given the low materials cost, easy and well-established electrode fabrication procedure, and high demonstrated photoelectrochemical performance, the Si-MWs@MoOxSyarrays reported here hold substantial promise for use as low-cost and efficient photocathodes for water reduction.
