Hybrid Device Turns Biomass Into Power

A hybrid solar-fuel cell can directly produce electricity by oxidizing biomass, according to a study in Nature Communications (2014, DOI: 10.1038/ncomms4208). Such a device could reduce dependence on petroleum, cut CO₂ emissions, and provide power for remote, off-grid use, say the developers, led by Georgia Tech chemical engineer Yulin Deng. One of the system’s key features is the presence of polyoxometalates (POMs) such as phosphomolybdic acid, a photocatalyst and charge carrier. When excited by sunlight, POMs in solution with biomass undergo reduction as they oxidize the organic compounds. A supply of oxygen on the fuel-cell side of the device reoxidizes the POMs and liberates electrons, generating current. Unlike most fuel cells, the device runs on impure starch, lignin, cellulose, and powdered wood. In addition, it does not rely on precious-metal anode catalysts.