Photocatalysis has received much attention owing to current energy and environmental crises. The use of an appropriate photocatalyst is important to a photocatalytic process. The development of photocatalysts that absorb light over a wide range of wavelengths and efficiently separate charge carriers remains a challenge and hot research topic. With strong visible-light-absorption ability, bismuth-containing photocatalysts are of great interest to scientists. However, measures have to be taken to enhance the light absorption efficiency and to lessen the problem of the recombination of charge carriers. Known approaches are the formation of heterojunctions through（1） loading of a noble metal,（2） semiconductor combination,（3） metal and nonmetal doping,（4） carbon-based material modification, and（5） Bi metal loading. The present review summarizes recent advances in this respect. Finally, the future development and potential applications of bismuth-containing photocatalysts with heterojunctions are briefly discussed.
The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts including organic bases, ionic liquids, supported catalysts, organic copolymers and carbon materials for the synthesis of cyclic carbonates by the cycloaddition of carbon dioxide to epoxides are reviewed. Recent advances in the design of the catalysts and the understanding of the reaction mechanism are summarized and discussed. The synergistic effects of organic bases and hydrogen bond donors, organic bases and nucleophilic anions, hydrogen bond donors and nucleophilic anions and active components and supports are highlighted. The challenge is to develop metal-free catalysts suitable for carbon dioxide capture and fixation. The ultimate goal is to synthesize cyclic carbonates in a flow reactor directly using carbon dioxide from industrial flue gas at ambient temperature and atmospheric pressure. By using synergetic effects, a multi-functional approach can meet the design strategy of metal-free catalysts for carbon dioxide adsorption and activation as well as epoxide ring opening.
