Hybrid catalysts for photoelectrochemical reduction of carbon dioxide: A prospective review on semiconductor/metal complex co-catalyst systems

Converting carbon dioxide (CO₂) into more valuable chemicals is of great interest in recent years. This is one potential solution to the two problems behind the significant increase of CO₂: global warming and limited fossil fuel resources. One technical effort is to develop CO₂ involved photoelectrochemical approaches for solar fuel production. Using water as both an electron donor and a proton source would mimic the photosynthesis in plants. In the presence of water, however, the semiconductor photocatalyst generally suffers from low product selectivity and quantum efficiency. On the other hand, metal complex catalysts have shown high product selectivity and current efficiency in electrochemical reduction of CO₂. Combining them as a co-catalyst with a semiconductor photocathode would improve the selectivity and efficiency. This article highlights the most recent progress in hybrid catalyst systems for photoelectrochemical reduction of CO₂. It also provides the prospective discussion of factors that affect the catalyst and cell performance as well as the future challenges.