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.