Recent Progress in the Photocatalytic Reduction of Carbon Dioxide.

Elimination or reduction of CO in the atmosphere is a serious problem faced by humankind, and it has become imperative for chemists to find ways of transforming undesirable CO to useful chemicals. One of the best means is the use of solar energy for the photochemical reduction of CO. In spite of considerable efforts, discovery of stable photocatalysts which work in the absence of scavengers has remained a challenge although encouraging results have been obtained in the photocatalytic reduction of CO in both gas and liquid phases. Semiconductor-based catalysts, multicomponent semiconductors, metal-organic frameworks (MOFs), and dyes as well as composites involving novel composite materials containing CN and MoS have been employed for the photoreduction process. Semiconductor heterostructures, especially those containing bimetallic alloys as well as chemical modification of oxides and other materials with aliovalent anion substitution (N and F in place of O), remain worthwhile efforts. In this article, we provide a brief perspective of the present status of photocatalytic reduction of CO in both liquid and gas phases.