Exploration of alternative materials for artificial photosynthesis

What is it about?

The activity of NaNbO3 and NaTaO3 perovskites for the photocatalytic reduction of CO2 is studied in this work. For this purpose, sodium niobate and tantalate have been prepared using solid-state reactions, extensively characterised by means of powder X-ray diffraction, UV-vis, photoluminescence and Raman spectroscopies and N2 adsorption isotherms, and tested in the gas-phase reduction of CO2 under UV light in a continuous flow photoreactor. NaNbO3 is constituted of an orthorhombically distorted perovskite structure, while a ca. 4.5 : 1 combination of the orthorhombic and monoclinic modifications is found in the tantalate. Both catalysts exhibit interesting intrinsic activities, with the tantalate material giving rise to a slightly higher performance. This is attributed to a compromise situation between electron–hole recombination and the reducing potential of conduction band electrons. In addition, a decrease in the competition of water protons for photogenerated electrons is observed with both catalysts with respect to TiO2.

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Photo by Sam Balye on Unsplash

Photo by Sam Balye on Unsplash

Why is it important?

A promising strategy for CO2 utilisation is the production of fuels and chemicals by means of photocatalytic reduction using water as an electron donor. This process, one of those encompassed in artificial photosynthesis (AP), is based on the use of semiconductor catalysts, and is particularly convenient taking into account that reactions are driven under soft conditions (temperature and pressure) and can take advantage of the use of a sustainable energy source.