Photocatalytic CO Reduction Using TiO-Based Photocatalysts and TiO Z-Scheme Heterojunction Composites: A Review.

Photocatalytic CO reduction is a most promising technique to capture CO and reduce it to non-fossil fuel and other valuable compounds. Today, we are facing serious environmental issues due to the usage of excessive amounts of non-renewable energy resources. In this aspect, photocatalytic CO reduction will provide us with energy-enriched compounds and help to keep our environment clean and healthy. For this purpose, various photocatalysts have been designed to obtain selective products and improve efficiency of the system. Semiconductor materials have received great attention and have showed good performances for CO reduction. Titanium dioxide has been widely explored as a photocatalyst for CO reduction among the semiconductors due to its suitable electronic/optical properties, availability at low cost, thermal stability, low toxicity, and high photoactivity. Inspired by natural photosynthesis, the artificial Z-scheme of photocatalyst is constructed to provide an easy method to enhance efficiency of CO reduction. This review covers literature in this field, particularly the studies about the photocatalytic system, TiO Z-scheme heterojunction composites, and use of transition metals for CO photoreduction. Lastly, challenges and opportunities are described to open a new era in engineering and attain good performances with semiconductor materials for photocatalytic CO reduction.