Wide spectrum response to photocatalyst decomposition water
2019-07-25 14:05:18
Solar photocatalytic decomposition of water to produce hydrogen is an important response to the photo-chemical conversion of solar energy and is considered a “holy grail†reaction in the chemical field. The photocatalytic water decomposition reaction mainly involves two half reactions of proton reduction and water oxidation. Among them, water oxidation is a reaction involving multiple electron transfer and thermodynamic climbing, and is considered as a speed control step to realize the above photochemical conversion of solar energy.
Solar photocatalytic conversion involves key scientific issues such as how to achieve broad-spectrum solar energy utilization, how to achieve efficient photo-generated charge separation, and catalytic conversion of the surface. However, as semiconductor catalysts absorb the red shift of the band edges, they drive photo-generated charge separation and water decomposition ( The ability to reduce and oxidize becomes weaker. Therefore, the full utilization of sunlight and the efficient separation of photo-generated charge are often not easy to achieve simultaneously. It is a very challenging problem to realize a high-efficiency water oxidation process of a photocatalyst with a broad spectrum response.
Recently, Li Can, Academician of the CAS State Key Laboratory of Catalysis and the National Laboratory of Clean Energy, and Zhang Fuxiang, a researcher of the “Hundred Talents Programâ€, responsible for the broad spectrum response to semiconductor photocatalytic water splitting, have made new progress: The interface between the wide-spectrum light-trapping material Ta3N5 (Eg: 2.1 eV, absorption edge band up to 600 nm) and the highly efficient oxidation promoter CoOx was modified by MgO nano-layers.
The above progress not only improves the contact and dispersion state of CoOx with its interface, but also acts as a passivation protection on the surface of semiconductor Ta3N5, and makes the photocatalytic system decompose water and emit oxygen quantum efficiency (AQE) under the excitation condition of visible light in the long wavelength band 500-600nm. , from the highest value of 5.2% of the literature to the current 11.3%. The results of relevant studies are published online in the journal German Applied Chemistry. The research work was funded by the Fund's major funds, the "973" project of the Ministry of Science and Technology, and the "Hundred Talents Program" talent project of the Chinese Academy of Sciences.
The co-catalyst can effectively promote photo-induced charge separation and catalytic conversion. Li Can's research team has clearly proposed a dual-cocatalyst strategy internationally (Acc. Chem. Res. 2013, 46, 2355). In recent years, in order to overcome the scientific challenge of broad spectrum response to water oxidation on photocatalysts, they developed a strategy for high-temperature loading of low-cost co-catalyst CoOx, which achieved better than traditional noble metal IrO2 and RuO2 catalysts on LaTiO2N (Eg: 2.1eV). Higher Oxygen Emission Performance (J.Am.Chem.Soc.2012, 134, 8348-8351.) Subsequently, this CoOx load strategy was successfully extended to the newly developed broad spectrum response nitrogen-doped oxide Sr5Ta4O15. On the -xNx and MgTa2O6-xNx material systems (J. Mater. Chem. 2013, 12, 5651; Chem. Commun. 2014, 50, 14415).
This study further utilizes the broad spectrum response of MgO nano-layers to the interface properties between semiconductor Ta3N5 and co-catalyst CoOx. By changing the hydrophilicity and hydrophobicity of the surface of the semiconductor material, the nano-dispersion of the co-catalyst and charge transfer between the interfaces are improved. The broad spectrum response to the highest quantum efficiency of the decomposition of water on the photocatalyst provides a new strategy for the development of an efficient photocatalytic system.
Solar photocatalytic conversion involves key scientific issues such as how to achieve broad-spectrum solar energy utilization, how to achieve efficient photo-generated charge separation, and catalytic conversion of the surface. However, as semiconductor catalysts absorb the red shift of the band edges, they drive photo-generated charge separation and water decomposition ( The ability to reduce and oxidize becomes weaker. Therefore, the full utilization of sunlight and the efficient separation of photo-generated charge are often not easy to achieve simultaneously. It is a very challenging problem to realize a high-efficiency water oxidation process of a photocatalyst with a broad spectrum response.
Recently, Li Can, Academician of the CAS State Key Laboratory of Catalysis and the National Laboratory of Clean Energy, and Zhang Fuxiang, a researcher of the “Hundred Talents Programâ€, responsible for the broad spectrum response to semiconductor photocatalytic water splitting, have made new progress: The interface between the wide-spectrum light-trapping material Ta3N5 (Eg: 2.1 eV, absorption edge band up to 600 nm) and the highly efficient oxidation promoter CoOx was modified by MgO nano-layers.
The above progress not only improves the contact and dispersion state of CoOx with its interface, but also acts as a passivation protection on the surface of semiconductor Ta3N5, and makes the photocatalytic system decompose water and emit oxygen quantum efficiency (AQE) under the excitation condition of visible light in the long wavelength band 500-600nm. , from the highest value of 5.2% of the literature to the current 11.3%. The results of relevant studies are published online in the journal German Applied Chemistry. The research work was funded by the Fund's major funds, the "973" project of the Ministry of Science and Technology, and the "Hundred Talents Program" talent project of the Chinese Academy of Sciences.
The co-catalyst can effectively promote photo-induced charge separation and catalytic conversion. Li Can's research team has clearly proposed a dual-cocatalyst strategy internationally (Acc. Chem. Res. 2013, 46, 2355). In recent years, in order to overcome the scientific challenge of broad spectrum response to water oxidation on photocatalysts, they developed a strategy for high-temperature loading of low-cost co-catalyst CoOx, which achieved better than traditional noble metal IrO2 and RuO2 catalysts on LaTiO2N (Eg: 2.1eV). Higher Oxygen Emission Performance (J.Am.Chem.Soc.2012, 134, 8348-8351.) Subsequently, this CoOx load strategy was successfully extended to the newly developed broad spectrum response nitrogen-doped oxide Sr5Ta4O15. On the -xNx and MgTa2O6-xNx material systems (J. Mater. Chem. 2013, 12, 5651; Chem. Commun. 2014, 50, 14415).
This study further utilizes the broad spectrum response of MgO nano-layers to the interface properties between semiconductor Ta3N5 and co-catalyst CoOx. By changing the hydrophilicity and hydrophobicity of the surface of the semiconductor material, the nano-dispersion of the co-catalyst and charge transfer between the interfaces are improved. The broad spectrum response to the highest quantum efficiency of the decomposition of water on the photocatalyst provides a new strategy for the development of an efficient photocatalytic system.
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