Au-Pd Tandem Photocatalysis for Nonoxidative Coupling of Methane toward Ethylene

Photocatalytic nonoxidative coupling of CH4 to C2H4 with a high rate and selectivity is considered challenging and impractical due to complex chemical pathways and unfavorable thermodynamics. This work introduces a strategy of tandem photocatalysis based on Au and Pd nanoparticles codeposited on a Bi2NbO5F photocatalyst, which divides the CH4 to C2H4 reaction into two distinct steps carried out in tandem by multiple activity components, i.e., CH4 coupling to C2H6 on Au and C2H6 dehydrogenation on Pd. As a result, the optimized Au-Pd/Bi2NbO5F shows CH4 coupling to C2H4 with a high yield of 22.6 mu mol g-1 h-1 and selectivity of 63% under simulated solar light irradiation. The reaction pathway is investigated by a series of activity experiments and in situ characterizations, demonstrating separate steps on Au and Pd. This work proposes a general strategy for the future design of photocatalysts to drive complex reactions efficiently and selectively based on the concept of a tandem system.