Mesoporous cobalt tungstate nanoparticles for efficient and stable visible-light-driven photocatalytic CO2 reduction

Ternary transition metal tungstates with low cost, high stability, and narrow band gap have exhibited great opportunities for photocatalysis, but their application in CO2 photoreduction is much less reported. Herein, we present the synthesis of mesoporous ternary cobalt tungstate (CoWO4) nanostructures as an advanced cocatalyst for photocatalytic CO2 reduction. A series of CoWO4 samples are prepared via a facile one-step hydrothermal method at different temperatures and fully checked by diverse physicochemical characterizations. The crystallinity and microstructure of CoWO4 can be facilely modulated by changing the synthesis temperature. In a classic tandem visible-light-sensitized system, the optimal CoWO4 cocatalyst affords excellent activity and stability for deoxygenative CO2 reduction, with a CO-yielding rate of 52.1 μmol h−1 (i.e. 17.4 mmol h−1 g−1), which is 22 times higher than the system without the cocatalyst. The collective photoelectrochemical measurements disclose that the cocatalyst can promote separation and migration of the charge carriers and provide abundant active sites to activate and reduce CO2 molecules, thus boosting CO2 reduction. This work may promote more research attention on exploring ternary transition metal tungstates as high-efficiency cofactors for CO2 photoreduction.