Route towards high-performance microfluidic fuel cells: a review

In the past twenty years, membrane-less microfluidic fuel cells (M-MFCs) have undergone a rapid development as emerging chip-based power sources. They possess enormous advantages compared to congeneric membrane-separated micro fuel cells, including low costs, simple structures, superior flexibility, and the absence of membrane-related issues. As a promising micro power source, the technology has undergone significant progress towards providing an affordable solution for powering chip-based microsystems. This review provides a broad and balanced insight into the route towards performance enhancement, starting with a general description of the technology. We analyse the power-generation properties with respect to the thermodynamics and electrochemical kinetics, including fuel/oxidant type, acid–base properties, operating temperature, and electro-catalytic reactions. Moreover, we provide much needed insight into the charge and mass transport phenomena, examining the influence of electron and ion transport, reactant concentration, fuel/electrolyte flow rate, gas–liquid two-phase flow, and the cell design based on various electrode structures and a virtual membrane. Finally, we discuss the open challenges and briefly provide guidance for future industrial M-MFCs’ applications.