An efficient CoAuPd/C catalyst for hydrogen generation from formic acid at room temperature.

Nowadays, searching for the effective hydrogen (H2) storage/ generation materials remains one of the most difficult challenges toward a fuel-cell-based H2 economy as a longterm solution for secure energy in future. Formic acid (FA, HCOOH), a major product of biomass processing with highenergy density, nontoxicity, and excellent stability at room temperature, has recently attracted tremendous research interests for H2 storage and generation. [2,3] Moreover, through the potential hydrogenation of waste carbon dioxide (CO2) from industry, FA can be regenerated, and this makes the storage of H2 in FA more attractive for a sustainable and reversible energy storage cycle. FA can be catalytically decomposed to H2 and CO2 through a dehydrogenation pathway (HCOOH(l)!H2(g)+ CO2(g), DG298K= 35.0 kJmol ). However, carbon monoxide (CO), which is a fatal poison to catalysts of fuel cells, can also be generated through a dehydration pathway (HCOOH(l)!H2O(l)+CO(g), DG298K= 14.9 kJmol ), depending on the catalysts, pH values of the solutions, as well as the reaction temperatures. Recently, much progress has been made on the heterogeneous catalysis for the selective dehydrogenation of FA. However, the thermodynamic and kinetic properties of FA dehydrogenation, especially without any extra additive, still need to be further promoted. 8] More importantly, all the reported heterogeneous catalysts up to now only consist of noble metals, including, for example, Pd, Au, Ag, and Pt, which greatly hinders their large-scale practical applications because of their high costs and low reserves in the earth s crust. The first-row transition metals (FRTM) in nanoscale, such as cobalt (Co) nanoparticles (NPs), have been widely investigated as the catalytic materials in many important reactions because of their potential activities and relatively low costs. Whereas, for FA dehydrogenation, nano-FRTM are easily etched by acidic FA solution. Hence, there is no report on application of nanocatalyst that includes FRTM for FA dehydrogenation. 8] When FRTM are alloyed with noble metals, their stabilities under acidic condition can be enhanced, which depends on the degree of alloying, metallic composition, and particle size of the material. Moreover, the incorporation of FRTM into the noble metals with the alloy structure may not only lead to the enhancement of the catalytic performance, but also reduce the consumption of the noble metals. In this sense, a novel strategy to improve the activities and lower the costs of solid catalysts for FA dehydrogenation is to design the polymetallic nanomaterials containing FRTM and noble metals within the stable alloy structures. Herein, we report the facile synthesis of the CoAuPd nanoalloy based on a non-noble metal and supported on carbon (CoAuPd/C) at room temperature (298 K). The elevated stability of Co in the protective nanoalloy structure makes its first application in FA dehydrogenation successful. More interestingly, the prepared CoAuPd/C with the lower consumption of noble metals exhibits the 100%H2 selectivity, highest activity, and excellent stability toward H2 generation from FA without any additive at 298 K. As shown in Scheme 1, CoAuPd/C is synthesized through a surfactant-free co-reduction method. Typically, for preparation of Co0.30Au0.35Pd0.35/C, 5.0 mL of aqueous solution containing CoCl2 (9.0 mm), Na2PdCl4 (10.5 mm), and HAuCl4