Efficient Interfacial Charge Transfer Enables Nearly 100% Selectivity for Solar-Light-Driven CO2 Conversion

The performance of transition-metal dichalcogenides (TMDs) as cocatalysts in CO2 photoreduction is considerably limited by their inherent poor conductivity and stacked structures. Herein, we report a rational assembly of TMDs on graphitic carbon nitride, which can be used as a cocatalyst ensemble for efficient and highly selective CO2 photoreduction. As an example, ReSe2 ultrathin nanosheet–graphitic carbon nitride (ReSe2/C3N4) composites are synthesized, in which efficient electron transfer is demonstrated by quasi in situ X-ray photoelectron spectroscopy and femtosecond transient absorption spectroscopy. In situ diffuse reflectance infrared Fourier-transform spectroscopy and theoretical calculations reveal that ReSe2/C3N4 composites could decrease the energy barrier of COOH* formation, thereby promoting the generation of COOH*. Consequently, optimized ReSe2/C3N4 composites exhibit a CO selectivity of 98% with a CO evolution rate of 19.6 μmol·g–1·h–1. This study demonstrates the rational design of TMD-based cocatalysts on 2D platforms for efficient and highly selective CO2 photoreduction.