Lang Pei,Zhe Xu,Zhan Shi,Heng Zhu,Shicheng Yan,Zhigang Zou
Charge separation/transfer and photocorrosion are two major factors limiting the photoelectrochemical (PEC) applications of the Ta3N5 photocatalyst. Herein, we have fabricated Ta3N5 single-crystal nanorods with Mg doping by flux-assisted crystal growth, aiming to shorten the charge transport distance and increase the electrical conductivity. The optimized Mg-doped Ta3N5 photoanodes exhibit an unprecedented PEC water splitting activity with an AM 1.5G photocurrent of 1.5 mA cm−2 at 1.23 VRHE. The high performance is attributed to the fact that the bulk modification, Mg doping, can induce oxygen-impurity surface states as effective electron trap centers, thus increasing the electrical conductivity of Ta3N5 and charge separation efficiency. After a conformal surface modification with CoOOH by a simple electrodeposition method as a water oxidation electrocatalyst to improve the hole extraction and reaction kinetics, the Mg-doped Ta3N5 photoanodes afford an over 4-fold increase in photocurrent (ca. 6.5 mA cm−2 at 1.23 VRHE) and about 70% retention of the initial photocurrent after 70 min irradiation at 1.0 VRHE. Our results testify that the bulk and surface co-modification is an effective route to develop high-performance PEC water splitting devices.
Ta 3 N 5 is a promising candidate for photoelectrochemical (PEC) water splitting. Recently gratifying photocurrents have been reported through various advanced techniques. However, obtaining high performance Ta 3 N 5 photoanode prepared by direct oxidation and nitridation remains challenging. In this work, efficient Ta 3 N 5 photoanode was fabricated on Ta foil by direct oxidation and nitridation method with LaCl 3 flux mediated treatment. The highest photoresponse (8.2 mA cm −2 @ 1.23 V RHE ) for direct oxidized and nitrided Ta 3 N 5 is achieved with the help of LaCl 3 flux, which is nearly doubled compared to the untreated counterparts. Theoretical analysis suggests an interfacial charge transfer in LaTaON 2 /Ta 3 N 5 heterostructure and significant increase in carrier concentration on La doped Ta 3 N 5 surface. The introduction of LaCl 3 flux brings a new look to this traditional method and it may potentially be applied to large area and low cost photoanodes.
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