Hydrogen production from formic acid decomposition at room temperature AgPd@Pd/TiO2 core–shell nanocatalyst prepared by microwave heating
Formic acid (FA: HCOOH) has attracted attention as a liquid fuel for use in hydrogen fuel cells because it has high energy density and it can be handled safely. For hydrogen production from FA decomposition at room temperature, novel AgPd@Pd core–shell nanocatalysts supported on TiO2 nanoparticles were prepared using microwave (MW) heating. The best hydrogen production rate, 46.03 L g-1 h-1, was obtained using Ag93Pd7@Pd/TiO2 at 27°C. Based on negative chemical shifts of Pd peaks found in XPS data, the enhancement of catalytic activity of AgPd@Pd particles in the presence of TiO2 was explained by the strong electron-donating effects of TiO2 + CO2.
Hydrogen gas (H2) has been anticipated for use as a clean energy resource that can replace fossil fuels. However, at ordinary temperatures and normal pressures, H2 is in a gaseous state, which is not compatible with storage in a small space. This constraint limits the miniaturization of efficient hydrogen production systems for mobile applications. To resolve this difficulty, a technique must be developed to extract H2 instantly from liquid fuels on a small scale. As such a liquid fuel, FA with low toxicity has attracted great attention because its liquid volume is only about 1/400 of H2 gas volume at room temperature, and because it is produced by a combination of CO2 and H2O with irradiation by sunlight (1). Extensive experimental and theoretical studies have been conducted to develop metallic catalysts for hydrogen production from FA decomposition (2−13).
Among the transition metal series tested for FA decomposition in the aqueous phase, Pd is the most active element (14). However, the initial decomposition rate of FA remains very poor, even when using small (3.2 nm) Pd nan ...