AuPd Nanoparticles Anchored on Nitrogen-Decorated Carbon Nanosheets with Highly Efficient and Selective Catalysis for the Dehydrogenation of Formic Acid

Formic acid (FA), a sustainable and safe hydrogen storage vector, has the advantages of nontoxicity, high hydrogen content (4.4 wt %) and low cost. However, the dehydrogenation of formic acid at near room temperature remains a big challenge in terms of favorable hydrogen release rate and CO-absence hydrogen production. Herein, a series of nitrogen-decorated carbon nanosheets (n-CNS) supported AuPd nanoparticles (NPs) were designed and employed as efficient catalysts to dehydrogenate FA for the first time. The catalyst AuPd NPs supported on n-CNS synthesized at hydrothermal temperature of 160 °C (AuPd/n-CNS-T h -160) exhibits excellent catalytic activity toward the dehydrogenation of FA compared with AuPd/g-carbon nitride (AuPd/g-C 3 N 4 ) and commercial Pd/C catalysts, reaching an initial turnover frequency (TOF) of 527 h –1, 100% hydrogen generation and selectivity at room temperature (25 °C), while the TOF achieves even 1896 h –1 at 60 °C. The enhanced catalytic performance can be attributed to the coordinated effect from Au–Pd alloying and the doped nitrogen atoms on carbon nanosheets. It is the first time to systematically probe the promoting mechanism of nitrogen on FA dehydrogenation. It is also illustrated that the promoting mechanism of N atoms on carbon nanosheets results from its nitrogen-bonding configuration, specifically, the ratio between graphitic N and pyridinic N. The high ratio of graphitic N to pyridinic N can modify the distribution of electron density and minimize the size of the metal nanoparticles, thereby greatly enhances the catalytic effect. The present study, by varying the catalysts’ composition and regulating the active material to boost the catalytic performance, provides a general pathway to further enhance the efficiency of hydrogen generation strongly depending on the properties of the support.