Highly Efficient Supported Palladium–Gold Alloy Catalysts for Hydrogen Storage Based on Ammonium Bicarbonate/Formate Redox Cycle

• Published in: ACS sustainable chemistry & engineering Vol. 7; no. 7; pp. 6522 - 6530
• Main Authors: Nakajima, Kengo, Tominaga, Mitsuhiro, Waseda, Moe, Miura, Hiroki, Shishido, Tetsuya
• Format: Journal Article
• Language: English
• Published: American Chemical Society 01-04-2019
• Subjects: Formate dehydrogenation; Bicarbonate hydrogenation; Hydrogen storage and release; Pd−Au alloy nanoparticles
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.8b04698

We have developed supported Pd–Au alloy catalysts for reversible hydrogen storage–release process with high efficiency based on the reversible reactions involving ammonium formate and bicarbonate. Supported Pd–Au random alloy catalysts exhibited a superior activity than supported monometallic Pd and Au catalysts in both bicarbonate hydrogenation and formate dehydrogenation under ambient conditions even without additives such as acids or bases. We used a series of Pd–Au alloy nanoparticles (NPs) supported on active carbon (Pd–Au/AC) with various Au/Pd ratios ranging from 0.1 to 10 to investigate the effects of the Au/Pd ratio. Turn over frequency (TOF) of bicarbonate hydrogenation increased monotonically with the Au/Pd ratio. Conversely, we found a volcano type relationship between the TOF of formate dehydrogenation and Au/Pd ratio and 1Au1Pd/AC catalyst exhibited the highest TOF value. On the basis of our structural and kinetic analysis, we discuss the correlation between the activity and the state of Pd and Au in supported Pd–Au alloy NPs.