Highly Active Carbon Supported Pd–Ag Nanofacets Catalysts for Hydrogen Production from HCOOH

Hydrogen is regarded as a future sustainable and clean energy carrier. Formic acid is a safe and sustainable hydrogen storage medium with many advantages, including high hydrogen content, nontoxicity, and low cost. In this work, a series of highly active catalysts for hydrogen production from formic acid are successfully synthesized by controllably depositing Pd onto Ag nanoplates with different Ag nanofacets, such as Ag{111}, Ag{100}, and the nanofacet on hexagonal close packing Ag crystal (Ag{hcp}). Then, the Pd–Ag nanoplate catalysts are supported on Vulcan XC-72 carbon black to prevent the aggregation of the catalysts. The research reveals that the high activity is attributed to the formation of Pd–Ag alloy nanofacets, such as Pd–Ag{111}, Pd–Ag{100}, and Pd–Ag{hcp}. The activity order of these Pd-decorated Ag nanofacets is Pd–Ag{hcp} > Pd–Ag{111} > Pd–Ag{100}. Particularly, the activity of Pd–Ag{hcp} is up to an extremely high value, i.e., TOF{hcp}= 19 000 ± 1630 h–1at 90 °C (lower limit value), which is more than 800 times higher than our previous quasi-spherical Pd–Ag alloy nanocatalyst. The initial activity of Pd–Ag{hcp} even reaches (3.13 ± 0.19) × 106h–1at 90 °C. This research not only presents highly active catalysts for hydrogen generation but also shows that the facet on the hcp Ag crystal can act as a potentially highly active catalyst.