WATER SPLITTING



Si photocathode



Appl. Catal. B Environ., 237, 158–165 (2018)



Si is a promising photocathode material for photoelectrochemical (PEC) water splitting, while developing highly active non-precious catalysts and stable semiconductor/catalyst interface is critical to bring solar water splitting into reality. Recently, significant progress has been made in two-dimensional (2D) materials, e.g. transition metal dichalcogenides (TMDs), due to that their edge sites show highly catalytic activity for H₂ evolution reaction (HER). To date, however, most of such studies have only been exploited as electrocatalysts for HER. Few works have achieved both efficient catalysis and stability when integrating TMD catalysts onto Si photocathodes for cheap PEC-HER.



The Co-W-S/Ti/n+p-Si photocathode presented by Fan et al. reveals good PEC-HER performance and impressive operation durability for solar hydrogen production. An ultrathin and homogeneous Co–W–S catalyst layer was produced on Ti/n+p-Si surface using a cheap wet chemical method, leading to more active sites for PEC reaction than pure WS₂. Simultaneously, the inserted 5 nm Ti buffer layer played an essential role in protecting Si surface and reducing resistances of charge transfer on the electrode/electrolyte interface. An energy conversion efficiency of 4.0% were obtained under simulated AM1.5G illumination, along with a long-term stability for 6 days of continuous PEC reaction. Our findings emphasize the importance of effective loading of the catalyst and protective layer on the photoelectrode, which subsequently enables the PEC process both efficient and stable.



Zhijie Wang (Institute of Semiconductors, CAS, Beijing, China)



doi: 10.1088/1674-4926/40/1/010201