Design and fabrication of semiconductor photocatalyst for photocatalytic reduction of CO2 to solar fuel

Abstract

The shortage of fossil fuels and the disastrous pollution of the environment have led to an increasing interest in artificial photosynthesis. The photocatalytic conversion of CO 2 into solar fuel is believed to be one of the best methods to overcome both the energy crisis and environmental problems. It is of significant importance to efficiently manage the surface reactions and the photo-generated charge carriers to maximize the activity and selectivity of semiconductor photocatalysts for photoconversion of CO 2 and H 2 O to solar fuel. To date, a variety of strategies have been developed to boost their photocatalytic activity and selectivity for CO 2 photoreduction. Based on the analysis of limited factors in improving the photocatalytic efficiency and selectivity, this review attempts to summarize these strategies and their corresponding design principles, including increased visible-light excitation, promoted charge transfer and separation, enhanced adsorption and activation of CO 2 , accelerated CO 2 reduction kinetics and suppressed undesirable reaction. Furthermore, we not only provide a summary of the recent progress in the rational design and fabrication of highly active and selective photocatalysts for the photoreduction of CO 2 , but also offer some fundamental insights into designing highly efficient photocatalysts for water splitting or pollutant degradation. INTRODUCTIONThe shortage of the energy supply and the problem of disastrous environmental pollution have been recognized as two main challenges in the near future [1]. It is a better way to efficiently and inexpensively convert solar energy into chemical fuels by developing an artificial photosynthetic (APS) system because solar fuels are high density energy carriers with long-term storage capacity. The most important and challenging reactions in APS-the photocatalytic water splitting into H 2 and O 2 (water reduction and oxidation) [2][3][4] and photoreduction of CO 2 to solar fuel, such as CH 4 and CH 3 OH [5,6] have been extensively studied since the photocatalytic water splitting on TiO 2 electrodes was discovered by Honda and Fujishima in 1972 [7]. The photocatalytic reduction of CO 2 by means of solar energy has attracted growing attention in the recent years, which 1 State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China 2 College of Science, South China Agricultural University, Guangzhou 510642, China 3 Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia * Corresponding author (email: jiaguoyu@yahoo.com) is also believed to be one of the best methods to overcome both global warming and energy crisis [8]. However, it is also generally thought that photocatalytic CO 2 reduction is a more complex and difficult process than H 2 production due to preferential H 2 production and low selectivity for the carbon species produced [9,10]. The progress achieved in the photoreduction of CO 2 is still far behind that in wate...

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