Jpn. J. Appl. Phys. 52, 08JF07 (2013)

Artificial photosynthesis holds out the attractive promise of using sunlight to convert atmospheric CO2 into organic fuels. Now, Masahiro Deguchi and co-workers in Japan have demonstrated that the process can be performed with an efficiency of 0.13%, comparable to that of natural photosynthesis in plants. This result was achieved by optimizing a previously reported photoelectrochemical CO2 conversion system that uses an AlGaN/GaN heterostructure photoelectrode to create electron–hole pairs for driving H2O oxidation and CO2 reduction. The team improved the efficiency of this system by a factor of 2.1 through using suitable electrolytes and through reducing energy losses by lowering the system resistance. This system has the advantages of not requiring an external bias or sacrificial materials. The researchers anticipate that the efficiency can be further increased by improving the catalysts and electrolytes used.