New efficient electrolysis process for direct hydrogen production from biomass; 16.7% of energy required for water electrolysis
Researchers at Georgia Tech, with colleagues at Hunan University and the Institute of Metal Research, Chinese Academy of Sciences, have devised a novel, efficient electrolysis approach for hydrogen evolution directly from native biomasses—cellulose, lignin and even wood and grass powders—to hydrogen at low temperature. A paper on their work is published in the RSC journal Energy and Environmental Science.
Using an aqueous polyoxometalate (POM)—phosphomolybdic acid (H3[PMo12O40] and silicotungstic acid (H4SiW12O40)—as a catalyst at the anode, the raw biomass is oxidized and electrons are transferred to POM molecules by heating or light-irradiation.
Polyoxometalates (POMs) are a subset of metal oxides that represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form dynamic structures that can range in size from the nano- to the micrometer scale. Heavy interest in POMs began in the 1990s.
In the current work, protons from biomass diffuse to the cathode and are reduced to hydrogen. The electric energy consumption can be as low as 0.69 kWh per normal cubic meter of H2 (Nm−3 H2) at 0.2 A cm−2—only 16.7% of the energy consumed for the reported water electrolysis. Unlike the traditional electrolysis of alcohols, a noble-metal catalyst is not required at the anode.
Wei Liu, Yong Cui, Xu Du, Zhe Zhang, Zisheng Chaob and Yulin Deng (2015) “High efficiency hydrogen evolution from native biomass electrolysis” Energy Environ. Sci. doi: 10.1039/C5EE03019F
De-Liang Long, Ryo Tsunashima, and Leroy Cronin (2010) “Polyoxometalates: Building Blocks for Functional Nanoscale Systems” Angew. Chem. Int. Ed. 49, 1736 – 1758 doi: 10.1002/anie.200902483