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

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 (mu EC-mu FC) 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 (mu EC) and microfluidic fuel cell (mu FC). A voltage applied to the mu EC induces two-phase flow in the mu EC-mu FC, resulting in the evolution of H-2 and O-2 gases that are transported to the mu FC by convection, and consumed to generate power. The catholyte-anolyte interface of the mu EC-mu FC 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 mu EC-mu FC operation in acidic and alkaline electrolytes based on the flow rate (1.4 - 1.6 mL min(-1)) and mu EC operating voltages (2.3 - 2.5 V) is done by polarization and power density curves. The mu EC-mu FC exhibited 4 h of stable tandem operation. The mu EC exhibits 99.98% energy conversion efficiency, with the mu FC attaining up to 50% fuel utilization in tandem mode.

Automated summary

The study demonstrates the tandem operation of a membraneless, two-phase flow microfluidic electrolysis cell and fuel cell, which is a step towards developing an independent micropower source. By controlling the flow rate of electrolyte, gas product mixing and crossover can be avoided. The tandem operation of mu EC-mu FC in acidic and alkaline electrolytes shows stable and efficient characteristics.