Conformal and continuous deposition of bifunctional cobalt phosphide layers on p-silicon nanowire arrays for improved solar hydrogen evolution

• DOI: 10.1007/s12274-018-2070-4
• Publication Date: 2018-04-27T06:36:24Z
• Authors: Sitaramanjaneva M...; Jerome Borme; Kang Yu; Junyuan Xu; Isilda Amorim; Joao Gaspar; Liang Qiao; Paulo Ferreira; Pedro Alpuim; Lifeng Liu
• Keywords: Science & Technology; Ciências Naturais::Ciências Físicas; photoelectrochemical water splitting; drop-casting; solar-driven hydrogen evolution; 02 engineering and technology; 7. Clean energy; Engenharia e Tecnologia::Engenharia dos Materiais; cobalt phosphide; Engenharia e Tecnologia::Nanotecnologia; silicon nanowire; 0210 nano-technology; Engenharia e Tecnologia::Engenharia Química

Vertically aligned p-silicon nanowire (SiNW) arrays have been extensively investigated in recent years as promising photocathodes for solar-driven hydrogen evolution. However, the fabrication of SiNW photocathodes with both high photoelectrocatalytic activity and long-term operational stability using a simple and affordable approach is a challenging task. Herein, we report conformal and continuous deposition of a di-cobalt phosphide (Co2P) layer on lithography-patterned highly ordered SiNW arrays via a cost-effective drop-casting method followed by a low-temperature phosphorization treatment. The as-deposited Co2P layer consists of crystalline nanoparticles and has an intimate contact with SiNWs, forming a well-defined SiNW@Co2P core/shell nanostructure. The conformal and continuous Co2P layer functions as a highly efficient catalyst capable of substantially improving the photoelectrocatalytic activity for the hydrogen evolution reaction (HER) and effectively passivates the SiNWs to protect them from photo-oxidation, thus prolonging the lifetime of the electrode. As aconsequence, the SiNW@Co2P photocathode with an optimized Co2P layer thickness exhibits a high photocurrent density of–21.9 mA·cm−2 at 0 V versus reversible hydrogen electrode and excellent operational stability up to 20 h for solar-driven hydrogen evolution, outperforming many nanostructured silicon photocathodes reported in the literature. The combination of passivation and catalytic functions in a single continuous layer represents a promising strategy for designing high-performance semiconductor photoelectrodes for use insolar-driven water splitting, which may simplify fabrication procedures andpotentially reduce production costs.