“On–Off” Control for On-Demand Hydrogen Production from the Dehydrogenation of Formic Acid

In order to effectively use the produced H2, the exploration of "on–off" control for on-demand hydrogen production is still a practical matter of supreme importance. Herein, a surfactant-free and facile method was successfully employed to synthesize Ag–Pd/C nanocomposites via simple alloying of commercial Pd/C and Ag for synergistically promoting H2 production from formic acid (FA). The optimal Ag16–Pd1/C nanocomposite presents the highest catalytic activity with a turnover frequency of 2444.10 h–1 and 100% H2 selectivity, whereas that of commercial Pd/C is only 619.39 h–1. Indeed, the activation energy has been effectively reduced from 40.45 kJ/mol (Pd/C) to 32.27 kJ/mol (Ag16–Pd1/C) by alloying commercial Pd/C with Ag. More importantly, the highly selective and effective "on–off" switch for hydrogen production upon the dehydrogenation of FA has been successfully achieved by varying the pH.