Conformal and continuous deposition of bifunctional cobalt phosphide layers on p-silicon nanowire arrays for improved solar hydrogen evolution
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.
Keywordssolar-driven hydrogen evolution silicon nanowire cobalt phosphide photoelectrochemical water splitting drop-casting
Unable to display preview. Download preview PDF.
This work was funded by ERDF funds through the Portuguese Operational Programme for Competitiveness and Internationalization COMPETE 2020, and national funds through FCT–The Portuguese Foundation for Science and Technology, under the project “PTDC/ CTM-ENE/2349/2014” (Grant Agreement No. 016660). The work is also partially funded by the Portugal-China Bilateral Collaborative Programme (FCT/21102/28/12/2016/S). L. F. Liu acknowledges the financial support of the FCT Investigator Grant (IF/01595/2014) and Exploratory Grant (IF/01595/2014/CP1247/CT0001). L. Qiao acknowledges the financial support of the Ministry of Science and Technology of China (Grant Agreement No. 2016YFE0132400).
- Thalluri, S. M.; Borme, J.; Xiong, D. H.; Xu, J. Y.; Li, W.; Amorim, I.; Alpuim, P.; Gaspar, J.; Fonseca, H.; Qiao, L. et al. Highly-ordered silicon nanowire arrays for photoelectrochemical hydrogen evolution: An investigation on the effect of wire diameter, length and inter-wire spacing. Sustainable Energy Fuels 2018. DOI: 10.1039/C7SE00591A.Google Scholar
- Bao, X. Q.; Petrovykh, D. Y.; Alpuim, P.; Stroppa, D. G.; Guldris, N.; Fonseca, H.; Costa, M.; Gaspar, J.; Jin, C. H.; Liu, L. F. Amorphous oxygen-rich molybdenum oxysulfide decorated p-type silicon microwire arrays for efficient photoelectrochemical water reduction. Nano Energy 2015, 16, 130–142.CrossRefGoogle Scholar
- Gholamvand, Z.; McAteer, D.; Backes, C.; McEvoy, N.; Harvey, A.; Berner, N. C.; Hanlon, D.; Bradley, C.; Godwin, I.; Rovetta, A. et al. Comparison of liquid exfoliated transition metal dichalcogenides reveals MoSe2 to be the most effective hydrogen evolution catalyst. Nanoscale 2016, 8, 5737–5749.CrossRefGoogle Scholar
- Wang, H. M.; Naghadeh, S. B.; Li, C. H.; Ying, L.; Allen, A. L.; Zhang, J. Z. Enhanced photoelectrochemical and photocatalytic activities of CdS nanowires by surface modification with MoS2 nanosheets. Sci. China Mater. 2018. DOI: 10.1007/s40843-017-9172-x.Google Scholar
- Roske, C. W.; Popczun, E. J.; Seger, B.; Read, C. G.; Pedersen, T.; Hansen, O.; Vesborg, P. C. K.; Brunschwig, B. S.; Schaak, R. E.; Chorkendorff, I. et al. Comparison of the performance of CoP-coated and Pt-coated radial junction n+p-silicon microwire-array photocathodes for the sunlight-driven reduction of water to H2(g). J. Phys. Chem. Lett. 2015, 6, 1679–1683.CrossRefGoogle Scholar
- Li, W.; Gao, X. F.; Wang, X. G.; Xiong, D. H.; Huang, P. P.; Song, W. G.; Bao, X. Q.; Liu, L. F. From water reduction to oxidation: Janus Co-Ni-P nanowires as high-efficiency and ultrastable electrocatalysts for over 3,000 h water splitting. J. Power Sources 2016, 330, 156–166.CrossRefGoogle Scholar
- Basu, M.; Zhang, Z. W.; Chen, C. J.; Chen, P. T.; Yang, K. C.; Ma, C. G.; Lin, C. C.; Hu, S. F.; Liu, R. S. Heterostructure of Si and CoSe2: A promising photocathode based on a non-noble metal catalyst for photoelectrochemical hydrogen evolution. Angew. Chem., Int. Ed. 2015, 54, 6211–6216.CrossRefGoogle Scholar
- Bae, D.; Shayestehaminzadeh, S.; Thorsteinsson, E. B.; Pedersen, T.; Hansen, O.; Seger, B.; Vesborg, P. C. K.; Olafsson, S.; Chorkendorff, I. Protection of Si photocathode using TiO2 deposited by high power impulse magnetron sputtering for H2 evolution in alkaline media. Sol. Energy Mater. Sol. Cell 2016, 144, 758–765.CrossRefGoogle Scholar