| 1 | Exploring the mechanism of Ta_(3)N_(5)/KTaO_(3) photocatalyst for overall water splitting by first-principles calculations显示文摘The rational fabrication of heterostructures is one of efficient strategies for improving photocatalytic performance of semiconductor photocatalysts.Very recently,Domen and co-workers found that Ta_(3)N_(5) single crystals grown on the surface of KTaO_(3) can accomplish photocatalytic overall water splitting for the first time.In order to comprehend the underlying mechanism of this photocatalytic system,we have performed a systematic study based on density functional theory first-principles calculations.Ta_(3)N_(5)(010)/KTaO_(3)(110)slab models have been built according to experimental observations by considering two common terminations of KTaO_(3)(110)surface,named as Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO.The formations of interfacial bonds are thermodynamically stable,showing a covalent interaction between two components of a heterostructure.Ta_(3)N_(5)/O_(2) has a higher mobility of photogenerated charge carriers and lower recombination rate of charge carriers than Ta_(3)N_(5)/KTaO.The light absorption of heterostructures displays the feature of KTaO_(3) in the short wavelength region and the characteristic of Ta_(3)N_(5) in the long wavelength region.The calculated band offsets show that Ta_(3)N_(5)/O_(2) and Ta_(3)N_(5)/KTaO have distinct Type-II band alignments,with Ta_(3)N_(5) as the accumulator of photoinduced electrons in the former and the collector of photogenerated holes in the latter,respectively.The difference in charge density and electrostatic potential between two components acts as a driving force to promote the transfer of electrons and holes to different domains of the interface,which is beneficial to extend the lifetime of photoinduced carriers.Our results demonstrate that the function of Ta_(3)N_(5) in Ta_(3)N_(5)/KTaO_(3) photocatalytic system is determined by the termination property of KTaO_(3)(110)surface,which provides a likely reason of the observed photocatalytic activity of overall water splitting achieved by Ta_(3)N_(5) synthesized by using KTaO_(3) as a precursor for the nitridation reaction. | Yanxia Ma Yumeng Fo Miaomiao Wang Xixi Liang Hao Dong Xin Zhou | 2021 | Journal of Energy Chemistry2021，30，5： | 0 |
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