Spinel‐Type Mixed Metal Sulfide NiCo₂S₄ for Efficient Photocatalytic Reduction of CO₂ with Visible Light

Mixed metal oxides with a spinel structure have exhibited great opportunities for photocatalytic CO 2 reduction; however, the abilities of their sulfide counterparts in this promising area are much less reported. Herein, we demonstrate the synthesis of a ternary metal sulfide, namely NiCo 2 S 4 , and its first application to catalyze the CO 2 photoreduction reaction under visible light irradiation. The NiCo 2 S 4 material is prepared through a coupled solvothermal‐ion exchange strategy, and is fully checked by diverse characterizations, including X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), energy‐dispersive X‐ray spectroscopy (EDX) and N 2 sorption measurements. Under visible light irradiation in a classic tandem photochemical system, this non‐noble‐metal NiCo 2 S 4 catalyst affords a considerable activity and high stability for CO 2 deoxygenative reduction, delivering a high CO‐liberating rate of 43.5 μmol mg −1 h −1 . The in‐situ PL and transient photocurrent measurements reveal that the spinel catalyst can hamper recombination and accelerate transfer of light‐excited charge carriers, and thus boosting the CO 2 reduction reaction. At last, a possible mechanism of the NiCo 2 S 4 ‐catalyzed CO 2 photoreduction reaction is proposed.