With the rapid development of economy,energy crisis and global warming are drawing more and more people's attention in recent years,however,photocatalytic reduction of CO2 by use of solar energy can solve these two problems at the same time.It is an efficient technology for the conversion of solar energy into different forms of chemical energy by combining the reductive half-reaction of CO2 with the oxidative half-reaction of water to achieve a carbon neutral cycle,which can be described vividly as killing two birds with one stone in terms of protecting the environment and supplying future energy[1].