Modifying microbes to work for us
Interdisciplinary researchers at the Nanyang Technological University and SCELSE in Singapore have significantly boosted both energy generation and hydrogen production by coupling chemically modified bacteria with Au-TiO2 photo-anodes.
The broadening of scientific research to encompass multiple areas of expertise has become and increasingly essential strategy for tackling many modern challenges, as we search for more sustainable solutions, particularly in the world’s urban centres. Such approaches have been embraced by biofilm researchers the world over to advance our knowledge of this default mode of microbial life and answer key research questions, both fundamental and applied.
The utility of such interdisciplinary approaches has been aptly demonstrated by Ngaw et al. (2015), who drew on expertise ranging from energy research and solar fuels, to chemistry, and microbial biofilm research to interface two separate platforms to the effect that both energy generation and hydrogen fuel production were significantly boosted.
The authors achieved the ‘remarkable’ novel process by coupling a photoelectrochemical (PEC) cell with a microbial fuel cell (MFC) – two previously independent platforms. In the combined PEC-MFC hybrid system, significant electrical current is generated from MFCs using biofilms of modified E. coli with electron transfer molecules (ETMs) inserted into their cell membranes. This current is then fed into a PEC cell, to supplement solar energy to produce hydrogen gas via a chemically modified gold-titanium oxide photo-anode. The ETMs vastly improve the efficiency of charge transfer capabilities in E. coli.
Conventional production of hydrogen gas consumes more energy than is released by burning it, so it is a great advantage to produce the gas in conjuction with a more efficient energy generation process.
The resulting system produced increased solar-generated electrical current – “70 times higher than that of a PEC cell” – and the simultaneous production of a continuous stream of hydrogen gas, thus demonstrating a technology that could “pave the way forward for new discoveries towards a sustainable hydrogen economy”.
Given the relative costs of some of the materials involved, especially regarding to the photo-anode, the challenge remains to create a system that is commercially viable for large-scale implementation. The interfacing of these previously independent PEC and MFC platforms, however, is a promising start.
Ngaw C. K., Wang V. B., Liu Z., Zhou Y., Kjelleberg S., Zhang Q., Tan T. T. Y. and Loo S. C. J. (2015). Enhancement in hydrogen evolution using Au-TiO2 hollow spheres with microbial devices modified with conjugated oligoelectrolytes. npj Biofilms and Microbiomes 1: 15020.