New Progress Made in the Photoelectrocatalytic Decomposition of Water to Hydrogen from Solar Energy Institute of Dalian Institute of Chemical Industry

Recently, the solar energy research team led by Li Can, a researcher of the State Key Laboratory of Catalysis and the National Laboratory of Clean Energy of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and the academician of the Chinese Academy of Sciences, Li Can, have discovered and proposed constructing a new concept and new strategy using the “hole storage layer”. After a highly efficient and stable solar photoelectrochemical decomposition water system (Angew.Chem.Int.Ed., 2014, 53, 7295-7299, Guiji Liu, Jingying Shi, Can Li, et al.) "Hydrogen" has made new progress in research. In the study of the design and construction of high-efficiency semiconductor photoanodes based on Ta3N5, the interface modification of “hole storage layer (HSL)” and electron blocking layer was combined with the surface molecular co-catalyst, and the composite photoanode system was constructed on the basis of The number of photocurrents (12.9 mA/cm2) near its theoretical limit was obtained at a water decomposition potential (1.23 V), and the results were published online in Energy & Environmental Science in the form of full text.

The photoelectrocatalytic decomposition of water to hydrogen is one of the ideal ways to use solar energy to prepare fuel. The water oxidation process on the photoanode is the decisive step and key scientific problem of solar water splitting. It has received extensive attention and research in academia. Li Can's research team has profoundly recognized the serious challenges faced by the Institute since the launch of the Photovoltaic Photocatalyst Decomposition Water Research. Around this scientific issue, photoelectrode preparation, surface co-catalyst modification, and photoelectrolytic cell design have been established. , carried out a series of studies and made continuous progress in research (Nanoscale 2014, 6, 2061-2066.; Faraday Discuss 2014, 176, 185-197; Phys. Chem. Chem. Phys., 2013, 15, 4589-4595; 2014 , 16, 15608-15614; J. Phys. Chem. B, 2015, 119, 3560-3566; 2015, 119, 19607-19612; ACS Appl. Mater. Interfaces, 2015, 7, 3791-3796, etc.).

Because of its energy band structure, the semiconductor material Ta3N5 meets the basic requirements of thermodynamic decomposition water, and has broad spectral response properties. It is one of the hot research materials in the field of hydrogen production from solar energy decomposition. However, this material is susceptible to photo-corrosion, the photocurrent starting potential is positive and its photocurrent is low (about 6-7 mA/cm2 in the literature), which seriously restricts the improvement of its photoelectrocatalytic performance. In 2014, the world’s highest stability Ta3N5-based photoanode system was constructed using ferrihydrite (Fh) as a “hole storage layer” (Angew.Chem.Int.Ed., 2014, 53, 7295-7299, Guiji Liu, Jingying After Shi, Can Li, et al.), the research team reported in 2015 that the Ni(OH)x/MoO3 double layer was used as another hole storage layer material, further improving the stability of the Ta3N5 photoanode. By more than 24 hours, the photocurrent starting potential has shifted negatively by ~600 mV (Guiji Liu, Jingying Shi, Can Li, et al., Chem. Eur. J. 2015, 21, 9624-9628). In a recent study, Ni(OH)x/Fh has been discovered as a "hole storage layer" in series, and its hole extraction and storage properties are used to control the relationship between Ta3N5 and the molecular co-catalyst (Ir/Co complex). The charge transfer, coupled with the electron blocking layer (TiOx), regulates the transmission direction of photocarriers, and the electron and hole recombination process is avoided to the utmost extent, obtaining current current >12mA/cm2 at 1.23V vs. RHE. The highest photocurrent. This research result expands the application of “hole storage layer” and forms a new strategy and new ideas for the rational design of high-efficiency photoelectrode, which provides an important research basis for the realization of high-efficiency solar fuel preparation.

The research was funded by the National Natural Science Foundation and the "973" project of the Ministry of Science and Technology.

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