Synergistic effects of Pd–Ag bimetals and g-C3N4 photocatalysts for selective and efficient conversion of gaseous CO2

Photoconversion of CO2 has been a promising method to decrease the emission of CO2 and obtain useful fuel source. Yet, the conversion efficiency and the selectivity of CO2 conversion by the photocatalysts have not been fully understood. Here, graphitic carbon nitride (g–C3N4)–based photocatalysts is fabricated with the incorporation of Pd–Ag bimetallic nanoparticles for CO2 conversion. The production rate and selective conversion feature of the photocatalysts are highly dependent on the molar ratio of the deposited Pd–Ag bimetals. Higher Pd content of the bimetals is favorable in selectively producing CH4 while lower Pd content preferably contribute to selective production of CO. The sample with 1:2 M ratio of Pd–Ag remarkably produces 5.42 μmol/g·h of CO and 4.03 μmol/g·h of CH4. Especially, the CH4 production rate is 40 times higher than that of bare g-C3N4 photocatalysts. Further understanding of the selective conversion and higher production rate by the decorated Pd–Ag bimetallic nanoparticles onto g-C3N4 are provided, elucidating the importance on the activation of g-C3N4 through bimetal structure.