Recently, an important progress in photocatalytic Z-scheme overall water splitting using wide visible-light-responsive semiconductors has been made in our group, which is under the cooperation with Prof. Kazunari Domen’s group from the University of Tokyo. It was reported that a MgTa₂O_6−xN_y/TaON heterostructure (the longest absorption wavelength is about 570 nm), fabricated by a simple one-pot nitridation route, could effectively improve the separation efficiency of photo-excited carriers, based on which an efficient wide visible-light-responsive photocatalytic Z-scheme overall water splitting system, with the highest apparent quantum efficiency (AQE) of 6.8% at 420 nm ever reported, was finally constructed. This work is now online published in the journal of Angewandte ChemieInternational Edition (http://onlinelibrary.wiley.com/doi/10.1002/anie.201502686/abstract).

Photocatalytic overall water splitting for hydrogen production is an ideal way to solve the problems of energy crisis and environment pollution, and meanwhile the development of wide visible-light-responsive semiconductor is the prerequisite to realize the highly efficient solar-to-chemical energy conversion. In the past few years, Our group has been devoting to the development of novel wide visible-light-responsive semiconductors, among which a series of nitrogen-doped layered/tunneled semiconductors has been demonstrated to be a new type of photocatalysts with wide visible light utilization promising for solar water splitting (J. Mater. Chem. A, 2013, 12, 5651；Chem. Commun.,2014, 50, 14415；Chin. J. Catal., 2014,35, 1431). However, the poor charge separation of this type of semiconductors restricts their final photocatalytic performances. To address this challenge, a series of strategies,such as heterojunction, surface phase junction, spatial charge separation between different facets, has been developed in our group to enhance the charge separation efficiency. In this work, a MgTa₂O_6−xN_y/TaON heterostructure prepared by a novel one-pot nitridation route has been verified to be effective in promoting the charge separation yield and the photocatalytic Z-scheme overall water splitting performance, whose AQE is the highest one among the powered Z-scheme overall water splitting systems ever reported. This work not only provides a new method of constructing the heterostructure based on oxynitride and nitrogen-doped oxide semiconductors, but also fulfills our initial design and conception from the development of new materials to the final application in overall water splitting. All these findings can provide instructive basis of developing other highly efficient overall water splitting systems.

This work is financially supported by Major Program of National Natural Science Foundation of China, A3 Foresight Program, the Basic Research Program of China (973 project) and the “Hundred Talents Program” of Chinese Academy of Sciences. (by Shanshan Chen and FuxiangZhang)