Abstract: In the process of photocatalytic reduction of CO2，visible light could be absorbed perfectly by the catalyst with a narrowed band gap，but those absorbed light could not be entirely devoted to photocatalytic reduction of CO2，as photocatalytic reduction performance is directly related to energy band location and band structure changing has an important influence on redox ability. Beginning with the CO2 photocatalytic reduction basic principles，this paper is aimed to introduce the basic reduction process of CO2 by semiconductor photocatalyst，the decisive role of valence band and conduction band；to briefly discuss the existing mismatch problem of valence band and conduction band in the process of photocatalytic reduction of CO2；and also to describe how to improve the CO2 photocatalytic reduction efficiency using energy band match theory，such as crystal growth，composite materials，form “p-n junction” and the First Principles，which provides theoretical references for the selection and design of catalyst for the photocatalytic reduction of CO2.

Key words: carbon dioxide, photochemistry, reduction, energy band gap, semiconductor

摘要： 光催化还原CO2过程中，能带隙小的材料具备优良的可见光吸收性能，但吸收的可见光并不一定能够有效地被光催化还原作用所利用，这与催化剂能带位置有着直接关系，改变材料的能带结构对调节材料的氧化还原性能有着重要影响。本文从光催化还原CO2的基本原理出发，介绍了半导体催化剂光催化还原CO2的基本过程及催化剂价带、导带位置的决定性作用，简述了当今光催化还原CO2过程中存在的催化剂价带、导带不匹配问题，并从特定晶面生长、材料复合、形成p-n结、第一性原理等方面综述了如何利用能带匹配理论来提高光催化还原CO2效率，为光催化还原CO2的材料的选择和设计提供了理论依据。

关键词: 二氧化碳, 光化学, 还原, 能带, 半导体