1, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Figure 1: Schematic diagram of separation and transfer of photo-generated carriers in the CN/SNON-700 heterojunction under visible light irradiation.
Semiconductor-based photocatalysis has received tremendous attention in the last few decades because of its potential for solving current energy and environmental issues. In a semiconductor photocatalytic system, photoinduced electron-hole pairs are produced when a photocatalyst is irradiated by light with frequencies larger than that of its band gap . Semiconductor-based heterojunctions have been shown to overcome the drawbacks of low photocatalytic efficiency that result from electron−hole recombination and narrow photo-response range [3, 4] Different types of visible-light-active heterojunctions made by two different semiconductors will be presented [5-7]. With the example of our recent study based on the heterojunction of g-C3N4 and nitrogen-doped Sr2Nb2O7, the importance of design and preparation of heterojunctions to facilitate charge separation/migration for enhanced photocatalytic activity will be discussed.