Pd@HyWO3–x Nanowires Efficiently Catalyze the CO2 Heterogeneous Reduction Reaction with a Pronounced Light Effect

The design of photocatalysts able to reduce CO2 to value-added chemicals and fuels could enable a closed carbon circular economy. A common theme running through the design of photocatalysts for CO2 reduction is the utilization of semiconductor materials with high-energy conduction bands able to generate highly reducing electrons. Far less explored in this respect are low-energy conduction band materials such as WO3. Specifically, we focus attention on the use of Pd nanocrystal decorated WO3 nanowires as a heretofore-unexplored photocatalyst for the hydrogenation of CO2. Powder X-ray diffraction, thermogravimetric analysis, ultraviolet–visible-near infrared, and in situ X-ray photoelectron spectroscopy analytical techniques elucidate the hydrogen tungsten bronze, HyWO3–x, as the catalytically active species formed via the H2 spillover effect by Pd. The existence in HyWO3–x of Bronsted acid hydroxyls OH, W(V) sites, and oxygen vacancies (VO) facilitate CO2 capture and reduction reactions. Under solar irradi...