Hydrogen generation and utilization in a two-phase flow membraneless microfluidic electrolyzer-fuel cell tandem operation for micropower application

Abstract Advances in device miniaturization, ranging from sensors to transmitters, are driving the need for micro-scaled personalized on-demand power sources. Herein, the tandem operation of a membraneless, two-phase flow microfluidic electrolysis cell and fuel cell (µEC-µFC) is demonstrated, which is a step towards developing an independent micropower source. This device consists of a membraneless double Y-shaped microchannel that encompasses microelectrodes for the microfluidic electrolysis cell (µEC) and microfluidic fuel cell (µFC). A voltage applied to the µEC induces two-phase flow in the µEC-µFC, resulting in the evolution of H2 and O2 gases that are transported to the µFC by convection, and consumed to generate power. The catholyte-anolyte interface of the µEC-µFC behaves as a virtual membrane. The gas product mixing and crossover are averted by controlling the flow rate of electrolyte. Dimensionless numbers are used to characterize the flow in the microchannel. Tandem performance evaluation of µEC-µFC operation in acidic and alkaline electrolytes based on the flow rate (1.4 – 1.6 mL min−1) and µEC operating voltages (2.3 – 2.5 V) is done by polarization and power density curves. The µEC-µFC exhibited 4 h of stable tandem operation. The µEC exhibits 99.98% energy conversion efficiency, with the µFC attaining up to 50% fuel utilization in tandem mode.