Photoelectrochemical(PEC) water splitting is an ideal approach for renewable solar fuel production.The feasibility of PEC water-splitting cells relies on the development ofhigh-performance photoanodes. Significant progresses have been made in thediscovery of narrow bandgap semiconductors as promising photoanodes. However,the rational design of photoanode architecture that brings the potentials ofnarrow bandgap semiconductors into fruition for efficient PEC water oxidationstill remains as a key challenge.
Recently,the DICP & DNL research team led by Prof. Li Can designed and fabricated ahighly efficient photoanode system consisting of tantalum nitride (Ta3N5)semiconductor for light harvesting, hole-storage layers (Ni(OH)x/ferrhydrite)that mediate interfacial charge transfer from Ta3N5 tocoupled molecular catalysts (Co cubane and Ir complex) for water oxidation anda TiOx blocking layer that reduces the surface electron-holerecombination. The integrated Ta3N5 photoanode exhibits arecord photocurrent of 12.1 mA cm-2 at 1.23 V vs. the reversiblehydrogen electrode (RHE), which is nearly its theoretical photocurrent limitunder sunlight (12.9 mA cm-2), suggesting that almost each pair ofphotogenerated charge carriers in Ta3N5 has beenefficiently extracted and collected for solar water splitting. The manuscripthas been accepted as full paper to be published in Energy & Environmental Science (Guiji Liu,Jingying Shi, Can Li, et al., Energy Environ. Sci., 2016, DOI:10.1039/C5EE03802B).These findings further expand the application ofhole-storage layer, providing a new strategy for the rational design of highly efficient photoanode solar water splitting.
This work was supported by the National NaturalScience Foundation of China and the Ministry of Science and Technology ofChina. (By SHI Jingying & LIU Guiji)
Scheme for hole-storage layer and electronblocking layer on photoanode with molecular catalysts; Photocurrent > 12mA/cm2.
