Conformal and continuous deposition of bifunctional cobalt phosphide layers on p-silicon nanowire arrays for improved solar hydrogen evolution
solar-driven hydrogen evolution, silicon nanowire, cobalt phosphide, photoelectrochemical water splitting, drop-casting
ABSTRACT 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 lithographypatterned 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 a consequence, 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 in solar-driven water splitting, which may simplify fabrication procedures and potentially reduce production costs.
Tsinghua University Press
Sitaramanjaneva Mouli Thalluri,Jerome Borme,Kang Yu,Junyuan Xu,Isilda Amorim,Joao Gaspar,Liang Qiao,Paulo Ferreira,Pedro Alpuim,Lifeng Liu, Conformal and continuous deposition of bifunctional cobalt phosphide layers on p-silicon nanowire arrays for improved solar hydrogen evolution. NanoRes.2018, 11(9): 4823–4835